Pepco 10-Q 26 Oct 16 2016 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information	9 Months Ended
	Sep. 30, 2016shares
Entity Registrant Name	EXELON CORP
Entity Central Index Key	1,109,357
Document Type	10-Q
Document Period End Date	Sep. 30, 2016
Amendment Flag	false
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock Shares Outstanding	923,270,314
Exelon Generation Co L L C [Member]
Entity Registrant Name	EXELON GENERATION CO LLC
Entity Central Index Key	1,168,165
Entity Filer Category	Non-accelerated Filer
Commonwealth Edison Co [Member]
Entity Registrant Name	COMMONWEALTH EDISON CO
Entity Central Index Key	22,606
Entity Filer Category	Non-accelerated Filer
Entity Common Stock Shares Outstanding	127,017,143
PECO Energy Co [Member]
Entity Registrant Name	PECO ENERGY CO
Entity Central Index Key	78,100
Entity Filer Category	Non-accelerated Filer
Entity Common Stock Shares Outstanding	170,478,507
Baltimore Gas and Electric Company [Member]
Entity Registrant Name	BALTIMORE GAS AND ELECTRIC
Entity Central Index Key	9,466
Entity Filer Category	Non-accelerated Filer
Entity Common Stock Shares Outstanding	1,000
Pepco Holdings LLC [Member]
Entity Registrant Name	PEPCO HOLDINGS LLC
Entity Central Index Key	1,135,971
Entity Filer Category	Large Accelerated Filer
Potomac Electric Power Company [Member]
Entity Registrant Name	POTOMAC ELECTRIC POWER CO
Entity Central Index Key	79,732
Entity Filer Category	Non-accelerated Filer
Entity Common Stock Shares Outstanding	100
Delmarva Power and Light Company [Member]
Entity Registrant Name	DELMARVA POWER & LIGHT CO/DE
Entity Central Index Key	27,879
Entity Filer Category	Non-accelerated Filer
Entity Common Stock Shares Outstanding	1,000
Atlantic City Electric Company [Member]
Entity Registrant Name	ATLANTIC CITY ELECTRIC CO
Entity Central Index Key	8,192
Entity Filer Category	Non-accelerated Filer
Entity Common Stock Shares Outstanding	8,546,017

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Income (Unaudited) - USD ($) shares in Millions, $ in Millions		3 Months Ended			6 Months Ended	9 Months Ended
		Sep. 30, 2016	Mar. 23, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015
Gain (Loss) on Disposition of Assets	[1]						$ (26)
Operating revenues [Abstract]
Electrical Generation Revenue		$ 4,535		$ 4,564		$ 12,243	14,278
Gas Domestic Regulated Revenue		137		116		781	904
Operating revenues from affiliates		1		2
Regulated Operating Revenue		4,467		2,837		11,243	8,468
Electric Revenue		4,330		2,721		10,461	7,564
Revenues		9,002		7,401		23,486	22,746
Operating expenses
Purchased power		2,584		2,515		6,599	7,789
Cost of Purchased Power		1,170		776		2,863	2,421
Operating and maintenance		2,338		1,996		7,677	6,119
Depreciation and amortization		1,195		606		2,821	1,818
Taxes other than income		449		310		1,168	908
Total operating expenses		7,736		6,203		21,128	19,055
Gain (Loss) on Sale of Assets and Asset Impairment Charges		1		2		41	10
Operating income		1,267		1,200		2,399	3,701
Other income and (deductions)
Interest expense, net		(506)		(243)		(1,148)	(724)
Interest expense to affiliates		(10)		(10)		(31)	(31)
Other, net		120		(244)		377	(179)
Total other income and (deductions)		(396)		(497)		(802)	(934)
Income before income taxes		871		703		1,597	2,767
Income taxes		340		115		625	805
Income (Loss) from Equity Method Investments, Net of Dividends or Distributions		(5)		(1)		(16)	(3)
Net income		526		587		956	1,959
Net income (loss) attributable to noncontrolling interests and preference stock dividends		36		(42)		26	0
Net income attributable to common shareholders		490		629		930	1,959
Other comprehensive income (loss), net of income taxes
Prior service benefit reclassified to periodic benefit cost		(12)		(11)		(35)	(35)
Actuarial loss reclassified to periodic benefit cost		47		55		140	165
Other Comprehensive Income Pension And Non Pension Postretirement Benefit Plan Valuation Adjustment Net Of Tax		0		0		3	29
Unrealized gain (loss) on cash flow hedges		3		(3)		(4)	4
Other Comprehensive Income Unrealized Income Loss On Equity Investments Arising During Period Net Of Tax		(4)		0		(10)	0
Unrealized loss on marketable securities		0		(1)		0	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax		2		(8)		8	(17)
Other comprehensive income		36		32		96	88	[2]
Comprehensive income		562		619		1,052	2,047
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest		31		(42)		21	0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest		$ 531		$ 661		$ 1,031	$ 2,047
Average shares of common stock outstanding:
Weighted average common shares outstanding — basic		925		913		924	879
Average common shares outstanding — diluted		927		915		926	883
Earnings per average common share:
Earnings per share - basic (in usd per share)		$ 0.53		$ 0.69		$ 1.01	$ 2.23
Earnings per average common share - diluted
Earnings per share - diluted (in usd per share)		0.53		0.69		1	2.22
Dividends per common share (in usd per share)		$ 0.318		$ 0.31		$ 0.946	$ 0.93
PECO Energy Co [Member]
Operating revenues [Abstract]
Gas Domestic Regulated Revenue		$ 48		$ 48		$ 322	$ 435
Operating revenues from affiliates		2		1		5	1
Electric Revenue		738		691		1,966	1,950
Revenues		788		740		2,293	2,386
Operating expenses
Utilities Operating Expense, Purchased Power		171		207		466	584
Purchased power and fuel from affiliates		91		61		233	171
Utilities Operating Expense, Fuel Used		10		10		110	198
Operating and maintenance		168		166		501	529
Operating and maintenance from affiliates		31		30		103	80
Depreciation and amortization		67		68		201	198
Taxes other than income		46		44		126	125
Total operating expenses		584		586		1,740	1,885
Gain (Loss) on Disposition of Other Assets						0	1
Operating income		204		154		553	502
Other income and (deductions)
Interest expense, net		(27)		(25)		(83)	(75)
Interest expense to affiliates		(3)		(3)		(9)	(9)
Other, net		2		1		6	3
Total other income and (deductions)		(28)		(27)		(86)	(81)
Income before income taxes		176		127		467	421
Income taxes		54		37		121	122
Net income		122		90		346	299
Other comprehensive income (loss), net of income taxes
Other comprehensive income	[2]						0
Comprehensive income		122		90		346	299
Exelon Generation Co L L C [Member]
Gain (Loss) on Disposition of Assets							0
Operating revenues [Abstract]
Electrical Generation Revenue		4,533		4,562		12,234	14,270
Operating revenues from affiliates		502		206		1,129	571
Revenues		5,035		4,768		13,363	14,841
Operating expenses
Cost of Purchased Power		2,584		2,516		6,599	7,789
Purchased power and fuel from affiliates		5		3		10	11
Operating and maintenance		1,189		1,088		3,855	3,399
Operating and maintenance from affiliates		147		153		478	461
Depreciation and amortization		632		264		1,329	774
Taxes other than income		136		123		380	369
Total operating expenses		4,693		4,147		12,651	12,803
Gain (Loss) on Sale of Assets and Asset Impairment Charges		0		1		31	7
Operating income		342		622		743	2,045
Other income and (deductions)
Interest expense, net		(67)		(56)		(243)	(236)
Interest expense to affiliates		(10)		(12)		(30)	(33)
Other, net		185		(257)		395	(193)
Total other income and (deductions)		108		(325)		122	(462)
Income before income taxes		450		297		865	1,583
Income taxes		173		(36)		293	371
Income (Loss) from Equity Method Investments, Net of Dividends or Distributions		(6)		(1)		(16)	(4)
Net income		271		332		556	1,208
Net income (loss) attributable to noncontrolling interests		35		(45)		18	(10)
Net income attributable to membership interest		236		377		538	1,218
Other comprehensive income (loss), net of income taxes
Unrealized gain (loss) on cash flow hedges		1		(3)		(3)	(7)
Other Comprehensive Income Unrealized Income Loss On Equity Investments Arising During Period Net Of Tax		0		0		(4)	0
Unrealized loss on marketable securities		1		(2)		1	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax		2		(8)		8	(17)
Other comprehensive income		4		(13)		2	(24)	[2]
Comprehensive income		275		319		558	1,184
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest		245		364		545	1,194
Commonwealth Edison Co [Member]
Operating revenues [Abstract]
Operating revenues		1,493		1,375		4,019	3,706
Operating revenues from affiliates		4		1		12	3
Revenues		1,497		1,376		4,031	3,709
Operating expenses
Cost of Purchased Power		435		388		1,104	974
Purchased power and fuel from affiliates		19		2		37	17
Operating and maintenance		327		353		950	1,023
Operating and maintenance from affiliates		50		51		163	143
Depreciation and amortization		196		176		574	528
Taxes other than income		82		79		222	225
Total operating expenses		1,109		1,049		3,050	2,910
Gain (Loss) on Sale of Assets and Asset Impairment Charges		1		0		6	0
Operating income		389		327		987	799
Other income and (deductions)
Interest expense, net		(194)		(80)		(364)	(238)
Interest expense to affiliates		(3)		(3)		(10)	(10)
Other, net		(80)		4		(72)	14
Total other income and (deductions)		(277)		(79)		(446)	(234)
Income before income taxes		112		248		541	565
Income taxes		75		99		244	226
Net income		37		149		297	339
Other comprehensive income (loss), net of income taxes
Comprehensive income		37		149		297	339
Baltimore Gas and Electric Company [Member]
Operating revenues [Abstract]
Gas Domestic Regulated Revenue		72		66		412	468
Operating revenues from affiliates		7		3		16	10
Electric Revenue		733		656		1,993	1,910
Revenues		812		725		2,421	2,388
Operating expenses
Utilities Operating Expense, Purchased Power		164		159		399	497
Purchased power and fuel from affiliates		182		141		486	373
Utilities Operating Expense, Fuel Used		14		11		109	167
Operating and maintenance		150		138		494	412
Operating and maintenance from affiliates		28		31		94	87
Depreciation and amortization		101		79		307	271
Taxes other than income		58		57		172	169
Total operating expenses		697		616		2,061	1,976
Gain (Loss) on Sale of Assets and Asset Impairment Charges				1			1
Operating income		115		110		360	413
Other income and (deductions)
Interest expense, net		(24)		(21)		(64)	(62)
Interest expense to affiliates		(4)		(4)		(12)	(11)
Other, net		5		4		16	13
Total other income and (deductions)		(23)		(21)		(60)	(60)
Income before income taxes		92		89		300	353
Income taxes		36		35		109	141
Net income		56		54		191	212
Preferred security dividends and redemption		2		3		8	10
Net income attributable to common shareholders		54		51		183	202
Other comprehensive income (loss), net of income taxes
Comprehensive income		56		54		191	212
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest		2		3		8	10
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest		54		51		183	202
Pepco Holdings LLC [Member] | Predecessor [Member]
Operating revenues [Abstract]
Gas Domestic Regulated Revenue			$ 57	19			129
Operating revenues from affiliates			0	0			0
Electric Revenue			1,096	1,317			3,680
Revenues			1,153	1,336			3,809
Operating expenses
Cost of Purchased Power			471	570			1,575
Purchased power and fuel from affiliates			0	0			0
Utilities Operating Expense, Fuel Used			26	9			71
Operating and maintenance			294	287			875
Operating and maintenance from affiliates			0	0			0
Depreciation and amortization			152	166			474
Taxes other than income			105	120			349
Total operating expenses			1,048	1,152			3,344
Operating income			105	184			465
Other income and (deductions)
Interest expense, net			(65)	(71)			(211)
Other, net			(4)	27			48
Total other income and (deductions)			(69)	(44)			(163)
Income before income taxes			36	140			302
Income taxes			17	49			105
Net income			19	91			197
Other comprehensive income (loss), net of income taxes
Actuarial loss reclassified to periodic benefit cost			1	0			4
Unrealized gain (loss) on cash flow hedges				1			1
Other comprehensive income			1	1			5
Comprehensive income			$ 20	92			202
Pepco Holdings LLC [Member] | Successor [Member]
Operating revenues [Abstract]
Gas Domestic Regulated Revenue		17			$ 46
Operating revenues from affiliates		11			34
Electric Revenue		1,366			2,485
Revenues		1,394			2,565
Operating expenses
Cost of Purchased Power		370			658
Purchased power and fuel from affiliates		207			362
Utilities Operating Expense, Fuel Used		6			17
Operating and maintenance		200			870
Operating and maintenance from affiliates		26			51
Depreciation and amortization		182			355
Taxes other than income		124			248
Total operating expenses		1,115			2,561
Operating income		279			4
Other income and (deductions)
Interest expense, net		(64)			(135)
Other, net		19			31
Total other income and (deductions)		(45)			(104)
Income before income taxes		234			(100)
Income taxes		68			(9)
Net income		166			(91)
Other comprehensive income (loss), net of income taxes
Actuarial loss reclassified to periodic benefit cost		0			0
Other comprehensive income		0			0
Comprehensive income		166			$ (91)
Potomac Electric Power Company [Member]
Gain (Loss) on Disposition of Assets		0				8
Operating revenues [Abstract]
Operating revenues from affiliates		1		1		3	4
Electric Revenue		634		591		1,692	1,637
Revenues		635		592		1,695	1,641
Operating expenses
Cost of Purchased Power		84		200		340	573
Purchased power and fuel from affiliates		129		0		223	0
Operating and maintenance		100		110		488	324
Operating and maintenance from affiliates		9		1		20	3
Depreciation and amortization		76		66		221	191
Taxes other than income		105		100		287	289
Total operating expenses		503		477		1,579	1,380
Operating income		132		115		124	261
Other income and (deductions)
Interest expense, net		(30)		(31)		(98)	(92)
Other, net		12		8		28	21
Total other income and (deductions)		(18)		(23)		(70)	(71)
Income before income taxes		114		92		54	190
Income taxes		35		32		34	62
Net income		79		60		20	128
Other comprehensive income (loss), net of income taxes
Comprehensive income		79		60		20	128
Delmarva Power and Light Company [Member]
Gain (Loss) on Disposition of Assets		4		0		4	0
Operating revenues [Abstract]
Gas Domestic Regulated Revenue		17		19		102	129
Operating revenues from affiliates		2		1		6	4
Electric Revenue		312		294		866	871
Revenues		331		314		974	1,004
Operating expenses
Utilities Operating Expense, Purchased Power		81		143		297	435
Purchased power and fuel from affiliates		63		0		110	0
Utilities Operating Expense, Fuel Used		6		8		41	65
Operating and maintenance		50		77		327	233
Operating and maintenance from affiliates		5		0		11	1
Depreciation and amortization		44		40		120	113
Taxes other than income		14		14		42	39
Total operating expenses		263		282		948	886
Operating income		72		32		30	118
Other income and (deductions)
Interest expense, net		(12)		(12)		(37)	(37)
Other, net		3		4		9	8
Total other income and (deductions)		(9)		(8)		(28)	(29)
Income before income taxes		63		24		2	89
Income taxes		19		9		18	34
Net income		44		15		(16)	55
Other comprehensive income (loss), net of income taxes
Comprehensive income		44		15		(16)	55
Atlantic City Electric Company [Member]
Gain (Loss) on Disposition of Assets		0				1
Operating revenues [Abstract]
Operating revenues from affiliates		1		1		3	2
Electric Revenue		420		385		979	1,001
Revenues		421		386		982	1,003
Operating expenses
Cost of Purchased Power		206		214		491	552
Purchased power and fuel from affiliates		15		0		29	0
Operating and maintenance		62		69		336	205
Operating and maintenance from affiliates		5		1		10	2
Depreciation and amortization		49		49		130	135
Taxes other than income		1		2		6	5
Total operating expenses		338		335		1,002	899
Operating income		83		51		(19)	104
Other income and (deductions)
Interest expense, net		(15)		(16)		(47)	(48)
Other, net		2		1		8	4
Total other income and (deductions)		(13)		(15)		(39)	(44)
Income before income taxes		70		36		(58)	60
Income taxes		23		14		(8)	23
Net income		47		22		(50)	37
Other comprehensive income (loss), net of income taxes
Comprehensive income		$ 47		$ 22		$ (50)	$ 37
[1]	In January 2015, in connection with Generation's $750 million issuance of five-year Senior Unsecured Notes, Exelon terminated certain floating-to-fixed interest rate swaps. As the original forecasted transactions were a series of future interest payments over a ten year period, a portion of the anticipated interest payments were probable not to occur. As a result, $26 million of anticipated payments were reclassified from AOCI to Other, net in Exelon's Consolidated Statement of Operations and Comprehensive Income.
[2]	All amounts are net of tax and noncontrolling interest. Amounts in parenthesis represent a decrease in AOCI.

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Cash flows from operating activities
Net income	$ 956	$ 1,959
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, depletion and accretion, including nuclear fuel and energy contract amortization	4,009	2,930
Impairment of long-lived assets and losses on regulatory assets	274	25
Gain on sales of assets	(41)	(10)
Deferred income taxes and amortization of investment tax credits	623	241
Net fair value changes related to derivatives	100	(363)
Gain (Loss) on Investments	243	(221)
Other non-cash operating activities	1,224	856
Changes in assets and liabilities:
Inventories	21	65
Accounts receivable	(296)	175
Accounts payable and accrued expenses	296	(115)
Option premiums (paid) received, net	(24)	27
Increase (Decrease) Cash Collateral from Counterparties	757	115
Income taxes	527	300
Pension and non-pension postretirement benefit contributions	(283)	(430)
Other assets and liabilities	(537)	(322)
Net cash flows provided by operating activities	7,363	5,674
Cash flows from investing activities
Capital expenditures	(6,368)	(5,443)
Proceeds from nuclear decommissioning trust fund sales	7,914	4,551
Investment in nuclear decommissioning trust funds	(8,093)	(4,737)
Acquisition of businesses, net of cash acquired	(6,896)	(28)
Proceeds from Sale of Property Held-for-sale	49	145
Proceeds from termination of direct financing lease investment	360	0
Change in restricted cash	(75)	(70)
Other investing activities	(110)	(107)
Net cash flows used in investing activities	(13,219)	(5,689)
Cash flows from financing activities
Changes in short-term borrowings	(1,014)	230
Proceeds from short-term borrowings with maturities greater than 90 days	195	0
Issuance of long-term debt	4,488	5,909
Proceeds from (Repayments of) Other Long-term Debt	(30)	0
Retirement of long-term debt	(944)	(1,745)
Dividends paid on common stock	(873)	(819)
Proceeds from employee stock plans	36	24
Other financing activities	35	(65)
Repayments of Short-term Debt, Maturing in More than Three Months	(452)	0
Payments for Repurchase of Redeemable Preferred Stock	(190)	0
Net cash flows provided by financing activities	1,251	5,402
(Decrease) Increase in cash and cash equivalents	(4,605)	5,387
Cash and cash equivalents at beginning of period	6,502	1,878
Cash and cash equivalents at end of period	1,897	7,265
Proceeds from Issuance of Common Stock	0	1,868
Exelon Generation Co L L C [Member]
Cash flows from operating activities
Net income	556	1,208
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, depletion and accretion, including nuclear fuel and energy contract amortization	2,516	1,887
Impairment of long-lived assets and losses on regulatory assets	209	1
Gain on sales of assets	(31)	(7)
Deferred income taxes and amortization of investment tax credits	(133)	21
Net fair value changes related to derivatives	112	(252)
Gain (Loss) on Investments	243	(221)
Other non-cash operating activities	129	227
Changes in assets and liabilities:
Inventories	18	69
Accounts receivable	26	252
Change Receivables Payables From Affiliates	(56)	16
Accounts payable and accrued expenses	9	(146)
Option premiums (paid) received, net	(24)	27
Increase (Decrease) Cash Collateral from Counterparties	759	186
Income taxes	202	(70)
Pension and non-pension postretirement benefit contributions	(122)	(189)
Other assets and liabilities	(204)	(245)
Net cash flows provided by operating activities	3,723	3,206
Cash flows from investing activities
Capital expenditures	(2,651)	(2,774)
Proceeds from nuclear decommissioning trust fund sales	7,914	4,551
Investment in nuclear decommissioning trust funds	(8,093)	(4,737)
Acquisition of businesses, net of cash acquired	(255)	(28)
Proceeds from Sale of Property Held-for-sale	30	144
Change in restricted cash	(39)	(84)
Other investing activities	(184)	(92)
Net cash flows used in investing activities	(3,278)	(3,020)
Cash flows from financing activities
Repayments of Debt, Maturing in More than Three Months	(152)	0
Issuance of long-term debt	338	1,307
Proceeds from Debt, Maturing in More than Three Months	195	0
Retirement of long-term debt	(164)	(64)
Repayments of Related Party Debt	0	(550)
Other financing activities	92	(6)
Distribution to member	(167)	(2,368)
Proceeds from Contributions from Affiliates	142	55
Change in Exelon intercompany money pool borrowings	(785)	1,205
Net cash flows provided by financing activities	(501)	(421)
(Decrease) Increase in cash and cash equivalents	(56)	(235)
Cash and cash equivalents at beginning of period	431	780
Cash and cash equivalents at end of period	375	545
Commonwealth Edison Co [Member]
Cash flows from operating activities
Net income	297	339
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, depletion and accretion, including nuclear fuel and energy contract amortization	574	528
Gain on sales of assets	(6)	0
Deferred income taxes and amortization of investment tax credits	398	107
Other non-cash operating activities	122	312
Changes in assets and liabilities:
Inventories	4	(23)
Accounts receivable	(55)	(114)
Change Receivables Payables From Affiliates	(9)	(23)
Accounts payable and accrued expenses	145	(18)
Increase (Decrease) Cash Collateral from Counterparties	(2)	(43)
Income taxes	206	389
Pension and non-pension postretirement benefit contributions	(35)	(142)
Other assets and liabilities	104	34
Net cash flows provided by operating activities	1,749	1,346
Cash flows from investing activities
Capital expenditures	(1,950)	(1,670)
Change in restricted cash	0	2
Other investing activities	31	22
Net cash flows used in investing activities	(1,919)	(1,646)
Cash flows from financing activities
Changes in short-term borrowings	(284)	300
Issuance of long-term debt	1,200	400
Retirement of long-term debt	(665)	(260)
Dividends paid on common stock	(275)	(226)
Other financing activities	(17)	(4)
Contributions from parent	188	75
Net cash flows provided by financing activities	147	285
(Decrease) Increase in cash and cash equivalents	(23)	(15)
Cash and cash equivalents at beginning of period	67	66
Cash and cash equivalents at end of period	44	51
PECO Energy Co [Member]
Cash flows from operating activities
Net income	346	299
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, depletion and accretion, including nuclear fuel and energy contract amortization	201	198
Deferred income taxes and amortization of investment tax credits	69	11
Other non-cash operating activities	49	69
Changes in assets and liabilities:
Inventories	5	8
Accounts receivable	(50)	(15)
Change Receivables Payables From Affiliates	9	0
Accounts payable and accrued expenses	(12)	(19)
Income taxes	43	69
Pension and non-pension postretirement benefit contributions	(29)	(37)
Other assets and liabilities	(49)	(16)
Net cash flows provided by operating activities	582	567
Cash flows from investing activities
Capital expenditures	(448)	(435)
Change in restricted cash	0	(1)
Other investing activities	10	11
Net cash flows used in investing activities	(438)	(425)
Cash flows from financing activities
Issuance of long-term debt	300	0
Proceeds from (Repayments of) Other Long-term Debt	(30)	0
Dividends paid on common stock	(208)	(209)
Other financing activities	(3)	(2)
Contributions from parent	18	16
Change in Exelon intercompany money pool borrowings		55
Net cash flows provided by financing activities	77	(140)
(Decrease) Increase in cash and cash equivalents	221	2
Cash and cash equivalents at beginning of period	295	30
Cash and cash equivalents at end of period	516	32
Baltimore Gas and Electric Company [Member]
Cash flows from operating activities
Net income	191	212
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, depletion and accretion, including nuclear fuel and energy contract amortization	307	271
Impairment of long-lived assets and losses on regulatory assets	52
Gain on sales of assets		(1)
Deferred income taxes and amortization of investment tax credits	54	79
Other non-cash operating activities	109	111
Changes in assets and liabilities:
Inventories	(7)	10
Accounts receivable	(50)	62
Change Receivables Payables From Affiliates	(10)	(8)
Accounts payable and accrued expenses	43	34
Increase (Decrease) Cash Collateral from Counterparties	0	(27)
Income taxes	19	(6)
Pension and non-pension postretirement benefit contributions	(46)	(14)
Other assets and liabilities	(2)	(28)
Net cash flows provided by operating activities	660	696
Cash flows from investing activities
Capital expenditures	(611)	(506)
Change in restricted cash	(22)	2
Other investing activities	19	13
Net cash flows used in investing activities	(614)	(491)
Cash flows from financing activities
Changes in short-term borrowings	(210)	(70)
Issuance of long-term debt	850	0
Proceeds from (Repayments of) Other Long-term Debt	(190)
Retirement of long-term debt	(39)	(37)
Dividends paid on common stock	(134)	(116)
Other financing activities	(11)	(15)
Contributions from parent	28	6
Dividends paid on preference stock	(8)	(10)
Net cash flows provided by financing activities	286	(242)
(Decrease) Increase in cash and cash equivalents	332	(37)
Cash and cash equivalents at beginning of period	9	64
Cash and cash equivalents at end of period	341	27
Pepco Holdings LLC [Member] | Successor [Member]
Cash flows from financing activities
Cash and cash equivalents at end of period	299
Pepco Holdings LLC [Member] | Predecessor [Member]
Cash flows from operating activities
Net income		197
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, depletion and accretion, including nuclear fuel and energy contract amortization		474
Deferred income taxes and amortization of investment tax credits		107
Net fair value changes related to derivatives		(15)
Other non-cash operating activities		143
Changes in assets and liabilities:
Inventories		(5)
Accounts receivable		(211)
Change Receivables Payables From Affiliates		0
Accounts payable and accrued expenses		23
Increase (Decrease) Cash Collateral from Counterparties		0
Income taxes		12
Pension and non-pension postretirement benefit contributions		(12)
Other assets and liabilities		(112)
Net cash flows provided by operating activities		601
Cash flows from investing activities
Capital expenditures		(855)
Purchases of investments		0
Change in restricted cash		6
Other investing activities		14
Net cash flows used in investing activities		(835)
Cash flows from financing activities
Changes in short-term borrowings		99
Proceeds from short-term borrowings with maturities greater than 90 days		300
Issuance of long-term debt		408
Retirement of long-term debt		(163)
Dividends paid on common stock		(206)
Common stock issued for the Direct Stock Purchase and Dividend Reinvestment Plan and employee-related compensation		23
Distribution to member		0
Other financing activities		(24)
Contributions from parent		0
Change in Exelon intercompany money pool borrowings		0
Issuance of preferred stock		54
Net cash flows provided by financing activities		491
(Decrease) Increase in cash and cash equivalents		257
Cash and cash equivalents at beginning of period	26	15
Cash and cash equivalents at end of period		272
Potomac Electric Power Company [Member]
Cash flows from operating activities
Net income	20	128
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, depletion and accretion, including nuclear fuel and energy contract amortization	221	191
Deferred income taxes and amortization of investment tax credits	96	70
Other non-cash operating activities	168	42
Changes in assets and liabilities:
Inventories	3	(5)
Accounts receivable	(105)	(113)
Change Receivables Payables From Affiliates	44	2
Accounts payable and accrued expenses	7	(1)
Income taxes	139	0
Pension and non-pension postretirement benefit contributions	(6)	(7)
Other assets and liabilities	(83)	(94)
Net cash flows provided by operating activities	504	213
Cash flows from investing activities
Capital expenditures	(392)	(374)
Proceeds from Sale of Property Held-for-sale	12
Purchases of investments	(32)	0
Change in restricted cash	(31)	3
Other investing activities	8	14
Net cash flows used in investing activities	(435)	(357)
Cash flows from financing activities
Changes in short-term borrowings	(64)	(56)
Issuance of long-term debt	2	208
Retirement of long-term debt	(5)	(17)
Dividends paid on common stock	(92)	(91)
Other financing activities	0	(8)
Contributions from parent	187	112
Net cash flows provided by financing activities	28	148
(Decrease) Increase in cash and cash equivalents	97	4
Cash and cash equivalents at beginning of period	5	6
Cash and cash equivalents at end of period	102	10
Potomac Electric Power Company [Member] | Successor [Member]
Cash flows from investing activities
Acquisition of businesses, net of cash acquired	(33)
Delmarva Power and Light Company [Member]
Cash flows from operating activities
Net income	(16)	55
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, depletion and accretion, including nuclear fuel and energy contract amortization	120	113
Deferred income taxes and amortization of investment tax credits	69	40
Other non-cash operating activities	99	31
Changes in assets and liabilities:
Inventories	0	4
Accounts receivable	8	(33)
Change Receivables Payables From Affiliates	12	5
Accounts payable and accrued expenses	(8)	(5)
Increase (Decrease) Cash Collateral from Counterparties	1	0
Income taxes	52	0
Other assets and liabilities	(70)	(22)
Net cash flows provided by operating activities	267	188
Cash flows from investing activities
Capital expenditures	(260)	(246)
Proceeds from Sale of Property Held-for-sale	4
Change in restricted cash	0	5
Other investing activities	2	1
Net cash flows used in investing activities	(254)	(240)
Cash flows from financing activities
Changes in short-term borrowings	(88)	(40)
Issuance of long-term debt	0	200
Retirement of long-term debt	0	(100)
Dividends paid on common stock	(39)	(80)
Other financing activities	0	(2)
Contributions from parent	113	75
Net cash flows provided by financing activities	(14)	53
(Decrease) Increase in cash and cash equivalents	(1)	1
Cash and cash equivalents at beginning of period	5	4
Cash and cash equivalents at end of period	4	5
Atlantic City Electric Company [Member]
Cash flows from operating activities
Net income	(50)	37
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization, depletion and accretion, including nuclear fuel and energy contract amortization	130	135
Deferred income taxes and amortization of investment tax credits	14	13
Other non-cash operating activities	138	27
Changes in assets and liabilities:
Inventories	(1)	(1)
Accounts receivable	(32)	(87)
Change Receivables Payables From Affiliates	9	1
Accounts payable and accrued expenses	10	35
Income taxes	184	10
Other assets and liabilities	(87)	8
Net cash flows provided by operating activities	315	178
Cash flows from investing activities
Capital expenditures	(227)	(212)
Proceeds from Sale of Property Held-for-sale	2
Change in restricted cash	(4)	(6)
Other investing activities	2	2
Net cash flows used in investing activities	(227)	(216)
Cash flows from financing activities
Changes in short-term borrowings	(5)	98
Retirement of long-term debt	(35)	(46)
Dividends paid on common stock	(24)	(12)
Other financing activities	(1)	0
Contributions from parent	139	0
Net cash flows provided by financing activities	74	40
(Decrease) Increase in cash and cash equivalents	162	2
Cash and cash equivalents at beginning of period	3	2
Cash and cash equivalents at end of period	$ 165	$ 4

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Assets, Current [Abstract]
Cash and cash equivalents		$ 1,897	$ 6,502
Restricted cash and cash equivalents		321	205
Accounts receivable, net
Customer		4,061	3,187
Other		1,013	912
Mark-to-market derivative assets		754	1,365
Unamortized energy contract assets		126	86
Inventories, net
Fossil fuel and emission allowances		374	462
Materials and supplies		1,188	1,104
Regulatory assets		1,410	759
Other		1,064	752
Total current assets		12,208	15,334
Property, plant and equipment, net		71,214	57,439
Deferred debits and other assets
Regulatory assets		10,022	6,065
Nuclear decommissioning trust funds		11,076	10,342
Investments		592	639
Goodwill		6,672	2,672
Mark-to-market derivative assets		669	758
Unamortized energy contract assets		473	484
Pledged assets for Zion Station decommissioning		135	206
Other		1,474	1,445
Total deferred debits and other assets		31,113	22,611
Total assets		114,535	95,384
Liabilities, Current [Abstract]
Short-term borrowings		567	533
Long-term debt due within one year		2,512	1,500
Accounts payable		3,044	2,883
Accrued expenses		3,236	2,376
Payables to affiliates		8	8
Regulatory liabilities		548	369
Mark-to-market derivative liabilities (current liabilities)		222	205
Unamortized energy contract liabilities		452	100
Other		1,068	842
Energy Marketing Accounts Payable		356	302
Accounts Payable and Accrued Liabilities, Current		145
Total current liabilities		12,158	9,118
Long-term debt		32,330	23,645
Long-term debt to financing trusts		642	641
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net		18,115	13,776
Asset Retirement Obligations, Noncurrent		9,348	8,585
Pension obligations		3,765	3,385
Non-pension postretirement benefit obligations		1,921	1,618
Spent nuclear fuel obligation		1,023	1,021
Regulatory liabilities		4,437	4,201
Mark-to-market derivative liabilities (noncurrent liabilities)		422	374
Unamortized energy contract liabilities		927	117
Payable for Zion Station decommissioning		33	90
Other		1,928	1,491
Total deferred credits and other liabilities		41,919	34,658
Total liabilities	[1]	87,049	68,062
Redeemable Noncontrolling Interest, Equity, Common, Carrying Amount		26	28
Commitments and contingencies
Stockholders' Equity Attributable to Parent [Abstract]
Common stock		18,756	18,676
Treasury stock, at cost (35 shares at September 30, 2016 and December 31, 2015, respectively)		(2,327)	(2,327)
Retained earnings		12,121	12,068
Accumulated other comprehensive loss, net	[2]	(2,523)	(2,624)
Total shareholders’ equity		26,027	25,793
Preferred Stock, Value, Issued		0	193
Noncontrolling interests		1,433	1,308
Total equity		27,460	27,294
Total liabilities and shareholders’ equity		114,535	95,384
Member’s equity
Retained Earnings (Accumulated Deficit)		12,121	12,068
Accumulated other comprehensive loss, net	[2]	(2,523)	(2,624)
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	[3]	489	147
Variable Interest Entity, Primary Beneficiary [Member]
Assets, Current [Abstract]
Cash and cash equivalents		160	164
Restricted cash and cash equivalents		101	100
Accounts receivable, net
Customer		264	219
Other		42	43
Mark-to-market derivative assets		49	140
Inventories, net
Materials and supplies		192	181
Other		58	35
Total current assets		866	882
Property, plant and equipment, net		5,139	5,160
Deferred debits and other assets
Nuclear decommissioning trust funds		2,173	2,036
Goodwill		47	47
Mark-to-market derivative assets		32	53
Other		257	90
Total assets		8,514	8,268
Liabilities, Current [Abstract]
Long-term debt due within one year		191	111
Accounts payable		201	216
Accrued expenses		102	115
Mark-to-market derivative liabilities (current liabilities)		24	5
Unamortized energy contract liabilities		14	12
Other		34	13
Total current liabilities		566	472
Long-term debt		661	666
Deferred credits and other liabilities
Asset Retirement Obligations, Noncurrent	[4]	2,070	1,999
Pension obligations		9	9
Unamortized energy contract liabilities		26	39
Other		106	79
Total liabilities		3,438	3,264
Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Deferred debits and other assets
Total assets		8,514	8,268
Deferred credits and other liabilities
Total liabilities		3,438	3,264
Exelon Generation Co L L C [Member]
Assets, Current [Abstract]
Cash and cash equivalents		375	431
Restricted cash and cash equivalents		162	123
Accounts receivable, net
Customer		2,318	2,095
Other		301	360
Mark-to-market derivative assets		754	1,365
Unamortized energy contract assets		126	86
Receivables from affiliates		170	83
Inventories, net
Fossil fuel and emission allowances		292	384
Materials and supplies		849	880
Other		788	535
Total current assets		6,135	6,342
Property, plant and equipment, net		26,374	25,843
Deferred debits and other assets
Nuclear decommissioning trust funds		11,076	10,342
Investments		381	210
Goodwill		47	47
Mark-to-market derivative assets		630	733
Unamortized energy contract assets		472	484
Deferred Tax Assets, Net, Noncurrent		5	6
Pledged assets for Zion Station decommissioning		135	206
Other		692	627
Prepaid pension asset		1,621	1,689
Total deferred debits and other assets		15,059	14,344
Total assets		47,568	46,529
Liabilities, Current [Abstract]
Short-term borrowings		40	29
Long-term debt due within one year		254	90
Accounts payable		1,465	1,583
Accrued expenses		942	935
Payables to affiliates		118	104
Other Short-term Borrowings		461	1,252
Mark-to-market derivative liabilities (current liabilities)		203	182
Unamortized energy contract liabilities		76	100
Other		392	356
Energy Marketing Accounts Payable		356	302
Total current liabilities		4,307	4,933
Long-term debt		8,077	7,936
Long-term debt to affiliate		924	933
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net		5,684	5,845
Asset Retirement Obligations, Noncurrent		9,160	8,431
Non-pension postretirement benefit obligations		932	924
Spent nuclear fuel obligation		1,023	1,021
Due to Affiliate, Noncurrent		2,704	2,577
Mark-to-market derivative liabilities (noncurrent liabilities)		197	150
Unamortized energy contract liabilities		97	117
Payable for Zion Station decommissioning		33	90
Other		691	602
Total deferred credits and other liabilities		20,521	19,757
Total liabilities	[5]	33,829	33,559
Redeemable Noncontrolling Interest, Equity, Common, Carrying Amount		26	28
Commitments and contingencies
Stockholders' Equity Attributable to Parent [Abstract]
Retained earnings		3,072	2,701
Accumulated other comprehensive loss, net	[2]	(56)	(63)
Noncontrolling interests		1,432	1,307
Total liabilities and shareholders’ equity		47,568	46,529
Member’s equity
Members' Capital		9,265	8,997
Retained Earnings (Accumulated Deficit)		3,072	2,701
Accumulated other comprehensive loss, net	[2]	(56)	(63)
Total member's equity		12,281	11,635
Limited Liability Company (LLC) Members' Equity, Including Portion Attributable to Noncontrolling Interest		13,713	12,942
Exelon Generation Co L L C [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets, Current [Abstract]
Cash and cash equivalents		160	164
Restricted cash and cash equivalents		43	77
Accounts receivable, net
Customer		264	219
Other		42	43
Mark-to-market derivative assets		49	140
Inventories, net
Materials and supplies		192	181
Other		51	30
Total current assets		801	854
Property, plant and equipment, net		5,139	5,160
Deferred debits and other assets
Nuclear decommissioning trust funds		2,173	2,036
Goodwill		47	47
Mark-to-market derivative assets		32	53
Other		223	85
Total assets		8,415	8,235
Liabilities, Current [Abstract]
Long-term debt due within one year		64	27
Accounts payable		201	216
Accrued expenses		98	113
Mark-to-market derivative liabilities (current liabilities)		24	5
Unamortized energy contract liabilities		14	12
Other		34	13
Total current liabilities		435	386
Long-term debt		550	623
Deferred credits and other liabilities
Asset Retirement Obligations, Noncurrent		2,070	1,999	[4]
Pension obligations		9	9
Unamortized energy contract liabilities		26	39
Other		106	79
Total liabilities		3,196	3,135
Exelon Generation Co L L C [Member] | Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Deferred debits and other assets
Total assets		8,415	8,235
Deferred credits and other liabilities
Total liabilities		3,196	3,135
Commonwealth Edison Co [Member]
Assets, Current [Abstract]
Cash and cash equivalents		44	67
Restricted cash and cash equivalents		2	2
Accounts receivable, net
Customer		546	533
Other		259	272
Receivables from affiliates		359	199
Inventories, net
Regulatory assets		205	218
Other		63	63
Inventories, net		156	164
Total current assets		1,634	1,518
Property, plant and equipment, net		18,811	17,502
Deferred debits and other assets
Regulatory assets		987	895
Investments		6	6
Goodwill		2,625	2,625
Other		332	324
Receivable from affiliate		2,238	2,172
Prepaid pension asset		1,387	1,490
Total deferred debits and other assets		7,575	7,512
Total assets		28,020	26,532
Liabilities, Current [Abstract]
Short-term borrowings		10	294
Long-term debt due within one year		425	665
Accounts payable		625	660
Accrued expenses		1,045	706
Payables to affiliates		57	62
Regulatory liabilities		204	155
Mark-to-market derivative liabilities (current liabilities)		19	23
Other		78	70
Customer deposits		126	131
Total current liabilities		2,589	2,766
Long-term debt		6,606	5,844
Long-term debt to financing trusts		205	205
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net		5,320	4,914
Asset Retirement Obligations, Noncurrent		118	111
Non-pension postretirement benefit obligations		244	259
Regulatory liabilities		3,577	3,459
Mark-to-market derivative liabilities (noncurrent liabilities)		225	224
Other		526	507
Total deferred credits and other liabilities		10,010	9,474
Total liabilities		19,410	18,289
Commitments and contingencies
Stockholders' Equity Attributable to Parent [Abstract]
Common stock		1,588	1,588
Retained earnings		1,000	978
Other paid-in capital		6,022	5,677
Total shareholders’ equity		8,610	8,243
Total liabilities and shareholders’ equity		28,020	26,532
Member’s equity
Retained Earnings (Accumulated Deficit)		1,000	978
PECO Energy Co [Member]
Assets, Current [Abstract]
Cash and cash equivalents		516	295
Restricted cash and cash equivalents		33	3
Accounts receivable, net
Customer		271	258
Other		132	146
Receivables from affiliates		3	2
Inventories, net
Fossil fuel and emission allowances		38	43
Materials and supplies		26	26
Regulatory assets		37	34
Other		22	24
Prepaid utility taxes		43	11
Total current assets		1,121	842
Property, plant and equipment, net		7,400	7,141
Deferred debits and other assets
Regulatory assets		1,651	1,583
Investments		26	28
Other		24	21
Receivable from affiliate		466	405
Prepaid pension asset		353	347
Total deferred debits and other assets		2,520	2,384
Total assets		11,041	10,367
Liabilities, Current [Abstract]
Long-term debt due within one year		300	300
Accounts payable		282	281
Accrued expenses		108	109
Payables to affiliates		64	55
Regulatory liabilities		128	112
Other		26	29
Customer deposits		60	58
Total current liabilities		968	944
Long-term debt		2,579	2,280
Long-term debt to financing trusts		184	184
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net		2,964	2,792
Asset Retirement Obligations, Noncurrent		28	27
Non-pension postretirement benefit obligations		288	287
Regulatory liabilities		551	527
Other		87	90
Total deferred credits and other liabilities		3,918	3,723
Total liabilities		7,649	7,131
Commitments and contingencies
Stockholders' Equity Attributable to Parent [Abstract]
Common stock		2,473	2,455
Retained earnings		918	780
Accumulated other comprehensive loss, net	[2]	1	1
Total shareholders’ equity		3,392	3,236
Total liabilities and shareholders’ equity		11,041	10,367
Member’s equity
Retained Earnings (Accumulated Deficit)		918	780
Accumulated other comprehensive loss, net	[2]	1	1
Baltimore Gas and Electric Company [Member]
Assets, Current [Abstract]
Cash and cash equivalents		341	9
Restricted cash and cash equivalents		46	24
Accounts receivable, net
Customer		332	300
Other		100	112
Inventories, net
Fossil fuel and emission allowances		37	36
Materials and supplies		39	33
Regulatory assets		214	267
Other		5	3
Prepaid utility taxes		0	61
Total current assets		1,114	845
Property, plant and equipment, net		6,904	6,597
Deferred debits and other assets
Regulatory assets		508	514
Investments		12	12
Other		9	8
Prepaid pension asset		310	319
Total deferred debits and other assets		839	853
Total assets	[6]	8,857	8,295
Liabilities, Current [Abstract]
Short-term borrowings		0	210
Long-term debt due within one year		381	378
Accounts payable		239	209
Accrued expenses		144	110
Payables to affiliates		42	52
Regulatory liabilities		54	38
Other		35	35
Customer deposits		108	102
Total current liabilities		1,003	1,134
Long-term debt		2,281	1,480
Long-term debt to financing trusts		252	252
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net		2,149	2,081
Asset Retirement Obligations, Noncurrent		21	17
Non-pension postretirement benefit obligations		204	209
Regulatory liabilities		118	184
Other		72	61
Total deferred credits and other liabilities		2,564	2,552
Total liabilities	[6]	6,100	5,418
Stockholders' Equity Attributable to Parent [Abstract]
Common stock		1,388	1,367
Retained earnings		1,369	1,320
Total shareholders’ equity		2,757	2,687
Preferred Stock, Value, Issued		0	190
Total equity		2,757	2,877
Total liabilities and shareholders’ equity		8,857	8,295
Member’s equity
Retained Earnings (Accumulated Deficit)		1,369	1,320
Baltimore Gas and Electric Company [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets, Current [Abstract]
Cash and cash equivalents		0	0
Restricted cash and cash equivalents		44	23
Accounts receivable, net
Customer		0	0
Other		0	0
Mark-to-market derivative assets		0	0
Inventories, net
Materials and supplies		0	0
Other		0	0
Total current assets		44	23
Property, plant and equipment, net		0	0
Deferred debits and other assets
Nuclear decommissioning trust funds		0	0
Goodwill		0	0
Mark-to-market derivative assets		0	0
Other		3	3
Total assets		47	26
Liabilities, Current [Abstract]
Long-term debt due within one year		81	79
Accounts payable		0	0
Accrued expenses		2	2
Mark-to-market derivative liabilities (current liabilities)		0	0
Unamortized energy contract liabilities		0	0
Other		0	0
Total current liabilities		83	81
Long-term debt			41
Deferred credits and other liabilities
Asset Retirement Obligations, Noncurrent		0	0
Pension obligations	[4]	0	0
Unamortized energy contract liabilities		0	0
Other		0	0
Total liabilities		83	122
Baltimore Gas and Electric Company [Member] | Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Deferred debits and other assets
Total assets		47	26
Deferred credits and other liabilities
Total liabilities		83	122
Pepco Holdings LLC [Member]
Deferred debits and other assets
Goodwill		4,000	0
Pepco Holdings LLC [Member] | Predecessor [Member]
Assets, Current [Abstract]
Cash and cash equivalents			26
Restricted cash and cash equivalents			14
Accounts receivable, net
Customer			581
Other			319
Mark-to-market derivative assets			18
Inventories, net
Fossil fuel and emission allowances			9
Materials and supplies			122
Regulatory assets			305
Other			80
Total current assets			1,474
Property, plant and equipment, net			10,864
Deferred debits and other assets
Regulatory assets			2,277
Investments			80
Goodwill			1,406
Notes, Loans and Financing Receivable, Gross, Noncurrent			4
Mark-to-market derivative assets			0
Deferred Tax Assets, Net, Noncurrent			14
Other			69
Prepaid pension asset			0
Total deferred debits and other assets			3,850
Total assets			16,188
Liabilities, Current [Abstract]
Short-term borrowings			958
Long-term debt due within one year			456
Accounts payable			404
Accrued expenses			266
Payables to affiliates			0
Regulatory liabilities			66
Mark-to-market derivative liabilities (current liabilities)			0
Unamortized energy contract liabilities			0
Other			70
Customer deposits			107
Payables to Customers			0
Total current liabilities			2,327
Long-term debt			4,823
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net			3,406
Asset Retirement Obligations, Noncurrent			8
Pension obligations			466
Non-pension postretirement benefit obligations			215
Regulatory liabilities			147
Mark-to-market derivative liabilities (noncurrent liabilities)			0
Unamortized energy contract liabilities			0
Other			200
Total deferred credits and other liabilities			4,442
Total liabilities			11,592
Temporary Equity, Par Value			183
Stockholders' Equity Attributable to Parent [Abstract]
Retained earnings			617
Accumulated other comprehensive loss, net			$ (36)
Preferred Stock, Shares Outstanding			18,000
Total equity			$ 4,413
Preferred Stock, Par or Stated Value Per Share			$ 0.01
Total liabilities and shareholders’ equity			$ 16,188
Member’s equity
Members' Capital			3,832
Retained Earnings (Accumulated Deficit)			617
Accumulated other comprehensive loss, net			(36)
Total member's equity			4,413
Pepco Holdings LLC [Member] | Successor [Member]
Assets, Current [Abstract]
Cash and cash equivalents		299
Restricted cash and cash equivalents		49
Accounts receivable, net
Customer		595
Other		345
Mark-to-market derivative assets		0
Inventories, net
Fossil fuel and emission allowances		8
Materials and supplies		118
Regulatory assets		650
Other		54
Total current assets		2,118
Property, plant and equipment, net		11,311
Deferred debits and other assets
Regulatory assets		2,945
Investments		132
Goodwill		4,000
Notes, Loans and Financing Receivable, Gross, Noncurrent		4
Mark-to-market derivative assets		0
Deferred Tax Assets, Net, Noncurrent		7
Other		76
Prepaid pension asset		470
Total deferred debits and other assets		7,634
Total assets		21,063
Liabilities, Current [Abstract]
Short-term borrowings		517
Long-term debt due within one year		545
Accounts payable		335
Accrued expenses		325
Payables to affiliates		90
Exelon Money Pool Borrowing Current		7
Regulatory liabilities		101
Mark-to-market derivative liabilities (current liabilities)		0
Unamortized energy contract liabilities		376
Other		36
Customer deposits		125
Payables to Customers		90
Total current liabilities		2,547
Long-term debt		5,499
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net		3,746
Asset Retirement Obligations, Noncurrent		14
Pension obligations		0
Non-pension postretirement benefit obligations		139
Regulatory liabilities		167
Mark-to-market derivative liabilities (noncurrent liabilities)		0
Unamortized energy contract liabilities		830
Other		234
Total deferred credits and other liabilities		5,130
Total liabilities		13,176
Temporary Equity, Par Value		0
Stockholders' Equity Attributable to Parent [Abstract]
Retained earnings		(91)
Accumulated other comprehensive loss, net		0
Total liabilities and shareholders’ equity		21,063
Member’s equity
Members' Capital		7,978
Retained Earnings (Accumulated Deficit)		(91)
Accumulated other comprehensive loss, net		0
Total member's equity		7,887
Limited Liability Company (LLC) Members' Equity, Including Portion Attributable to Noncontrolling Interest		7,887
Pepco Holdings LLC [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Predecessor [Member]
Assets, Current [Abstract]
Cash and cash equivalents			0
Restricted cash and cash equivalents			12
Accounts receivable, net
Customer			0
Other			0
Mark-to-market derivative assets			0
Inventories, net
Materials and supplies			0
Other			0
Total current assets			12
Property, plant and equipment, net			0
Deferred debits and other assets
Nuclear decommissioning trust funds			0
Goodwill			0
Mark-to-market derivative assets			0
Other			18
Total assets			30
Liabilities, Current [Abstract]
Long-term debt due within one year			46
Accounts payable			0
Accrued expenses			2
Mark-to-market derivative liabilities (current liabilities)			0
Unamortized energy contract liabilities			0
Other			0
Total current liabilities			48
Long-term debt			124
Deferred credits and other liabilities
Asset Retirement Obligations, Noncurrent			0
Pension obligations	[4]		0
Unamortized energy contract liabilities			0
Other			0
Total liabilities			172
Pepco Holdings LLC [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Successor [Member]
Assets, Current [Abstract]
Cash and cash equivalents		0
Restricted cash and cash equivalents		15
Accounts receivable, net
Customer		0
Other		0
Mark-to-market derivative assets		0
Inventories, net
Materials and supplies		0
Other		5
Total current assets		20
Property, plant and equipment, net		0
Deferred debits and other assets
Nuclear decommissioning trust funds		0
Goodwill		0
Mark-to-market derivative assets		0
Other		31
Total assets		51
Liabilities, Current [Abstract]
Long-term debt due within one year		43
Accounts payable		0
Accrued expenses		2
Mark-to-market derivative liabilities (current liabilities)		0
Unamortized energy contract liabilities		0
Other		0
Total current liabilities		45
Long-term debt		111
Deferred credits and other liabilities
Asset Retirement Obligations, Noncurrent		0
Pension obligations	[4]	0
Unamortized energy contract liabilities		0
Other		0
Total liabilities		156
Pepco Holdings LLC [Member] | Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member] | Predecessor [Member]
Deferred debits and other assets
Total assets			30
Deferred credits and other liabilities
Total liabilities			172
Pepco Holdings LLC [Member] | Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member] | Successor [Member]
Deferred debits and other assets
Total assets		51
Deferred credits and other liabilities
Total liabilities		156
Potomac Electric Power Company [Member]
Assets, Current [Abstract]
Cash and cash equivalents		102	5
Restricted cash and cash equivalents		33	2
Accounts receivable, net
Customer		292	230
Other		148	261
Inventories, net
Materials and supplies		63	67
Regulatory assets		122	140
Other		4	21
Total current assets		764	726
Property, plant and equipment, net		5,409	5,162
Deferred debits and other assets
Regulatory assets		676	661
Investments		100	68
Other		4	4
Prepaid pension asset		266	287
Total deferred debits and other assets		1,046	1,020
Total assets		7,219	6,908
Liabilities, Current [Abstract]
Short-term borrowings		0	64
Long-term debt due within one year		12	11
Accounts payable		139	145
Accrued expenses		145	119
Payables to affiliates		74	30
Regulatory liabilities		20	15
Other		14	25
Customer deposits		53	46
Payables to Customers		63	0
Total current liabilities		520	455
Long-term debt		2,338	2,340
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net		1,845	1,723
Non-pension postretirement benefit obligations		46	49
Regulatory liabilities		24	29
Other		124	72
Total deferred credits and other liabilities		2,039	1,873
Total liabilities		4,897	4,668
Stockholders' Equity Attributable to Parent [Abstract]
Common stock		1,309	1,122
Other paid-in capital		1,013	1,118
Total shareholders’ equity		2,322	2,240
Total equity		2,322	2,240
Total liabilities and shareholders’ equity		7,219	6,908
Delmarva Power and Light Company [Member]
Assets, Current [Abstract]
Cash and cash equivalents		4	5
Accounts receivable, net
Customer		134	154
Other		44	96
Inventories, net
Fossil fuel and emission allowances		8	8
Materials and supplies		32	32
Regulatory assets		62	72
Other		17	21
Total current assets		301	388
Property, plant and equipment, net		3,222	3,070
Deferred debits and other assets
Regulatory assets		297	299
Goodwill		8	8
Other		7	2
Prepaid pension asset		188	202
Total deferred debits and other assets		500	511
Total assets		4,023	3,969
Liabilities, Current [Abstract]
Short-term borrowings		17	105
Long-term debt due within one year		218	204
Accounts payable		74	109
Accrued expenses		47	31
Payables to affiliates		34	20
Regulatory liabilities		46	49
Other		10	15
Customer deposits		37	31
Payables to Customers		12	0
Total current liabilities		495	564
Long-term debt		1,047	1,061
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net		1,016	945
Non-pension postretirement benefit obligations		19	19
Regulatory liabilities		100	111
Other		51	32
Total deferred credits and other liabilities		1,186	1,107
Total liabilities		2,728	2,732
Stockholders' Equity Attributable to Parent [Abstract]
Common stock		725	612
Retained earnings		570	625
Total shareholders’ equity		1,295	1,237
Total liabilities and shareholders’ equity		4,023	3,969
Member’s equity
Retained Earnings (Accumulated Deficit)		570	625
Atlantic City Electric Company [Member]
Assets, Current [Abstract]
Cash and cash equivalents		165	3
Restricted cash and cash equivalents		15	12
Accounts receivable, net
Customer		168	156
Other		46	242
Due from Affiliates		2	0
Inventories, net
Materials and supplies		22	23
Regulatory assets		89	98
Other		3	12
Prepaid utility taxes		10	0
Total current assets		520	546
Property, plant and equipment, net		2,456	2,322
Deferred debits and other assets
Regulatory assets		412	414
Notes, Loans and Financing Receivable, Gross, Noncurrent		4	4
Other		42	19
Prepaid pension asset		73	82
Total deferred debits and other assets		531	519
Total assets		3,507	3,387
Liabilities, Current [Abstract]
Short-term borrowings		0	5
Long-term debt due within one year		38	48
Accounts payable		110	96
Accrued expenses		72	70
Payables to affiliates		27	16
Regulatory liabilities		35	18
Other		7	14
Customer deposits		35	30
Payables to Customers		14	0
Total current liabilities		338	297
Long-term debt		1,129	1,153
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net		908	885
Non-pension postretirement benefit obligations		35	33
Regulatory liabilities		1	7
Other		31	12
Total deferred credits and other liabilities		975	937
Total liabilities		2,442	2,387
Stockholders' Equity Attributable to Parent [Abstract]
Common stock		912	773
Retained earnings		153	227
Total shareholders’ equity		1,065	1,000
Total liabilities and shareholders’ equity		3,507	3,387
Member’s equity
Retained Earnings (Accumulated Deficit)		153	227
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities		139	172
Atlantic City Electric Company [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets, Current [Abstract]
Cash and cash equivalents		0	0
Restricted cash and cash equivalents		15	12
Accounts receivable, net
Customer		0	0
Other		0	0
Mark-to-market derivative assets		0	0
Inventories, net
Materials and supplies		0	0
Other		0	0
Total current assets		15	12
Property, plant and equipment, net		0	0
Deferred debits and other assets
Nuclear decommissioning trust funds		0	0
Goodwill		0	0
Mark-to-market derivative assets		0	0
Other		19	18
Total assets		34	30
Liabilities, Current [Abstract]
Long-term debt due within one year		38	46
Accounts payable		0	0
Accrued expenses		2	2
Mark-to-market derivative liabilities (current liabilities)		0	0
Unamortized energy contract liabilities		0	0
Other		0	0
Total current liabilities		40	48
Long-term debt		99	124
Deferred credits and other liabilities
Asset Retirement Obligations, Noncurrent		0	0
Pension obligations	[4]	0	0
Unamortized energy contract liabilities		0	0
Other		0	0
Total liabilities		$ 139	$ 172
[1]	Exelon’s consolidated assets include $8,514 million and $8,268 million at September 30, 2016 and December 31, 2015, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Exelon’s consolidated liabilities include $3,438 million and $3,264 million at September 30, 2016 and December 31, 2015, respectively, of certain VIEs for which the VIE creditors do not have recourse to Exelon. See Note 3 - Variable Interest Entities.
[2]	All amounts are net of tax and noncontrolling interest. Amounts in parenthesis represent a decrease in AOCI.
[3]	These items represent amounts on the unconsolidated VIE balance sheets, not on Exelon’s or Generation’s Consolidated Balance Sheets. These items are included to provide information regarding the relative size of the unconsolidated VIEs.
[4]	Includes the CNEG retail gas pension obligation, which is presented as a net asset balance within the Prepaid pension asset line item on Generation’s balance sheet. See Note 13 - Retirement Benefits for additional details.
[5]	Generation’s consolidated assets include $8,415 million and $8,235 million at September 30, 2016 and December 31, 2015, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Generation’s consolidated liabilities include $3,196 million and $3,135 million at September 30, 2016 and December 31, 2015, respectively, of certain VIEs for which the VIE creditors do not have recourse to Generation. See Note 3 - Variable Interest Entities.
[6]	BGE’s consolidated assets include $47 million and $26 million at September 30, 2016 and December 31, 2015, respectively, of BGE’s consolidated VIE that can only be used to settle the liabilities of the VIE. BGE’s consolidated liabilities include $83 million and $122 million at September 30, 2016 and December 31, 2015, respectively, of BGE’s consolidated VIE for which the VIE creditors do not have recourse to BGE. See Note 3 - Variable Interest Entities.

Consolidated Balance Sheets (U5

Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Common Stock, Shares Authorized		2,000,000,000	2,000,000,000
Stockholders' Equity Attributable to Parent [Abstract]
Assets		$ 114,535	$ 95,384
Treasury Stock, Shares held		35,000,000
Exelon Generation Co L L C [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets		$ 47,568	46,529
Commonwealth Edison Co [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets		28,020	26,532
PECO Energy Co [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets		11,041	10,367
Baltimore Gas and Electric Company [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets	[1]	8,857	8,295
Potomac Electric Power Company [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets		7,219	6,908
Delmarva Power and Light Company [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets		4,023	3,969
Atlantic City Electric Company [Member]
Noncontrolling Interest in Variable Interest Entity		34	30
Stockholders' Equity Attributable to Parent [Abstract]
Assets		3,507	$ 3,387
Pepco Holdings LLC [Member] | Predecessor [Member]
Preferred Stock, Par or Stated Value Per Share			$ 0.01
Common Stock, Shares Authorized			400,000,000
Stockholders' Equity Attributable to Parent [Abstract]
Assets			$ 16,188
Common Stock, Shares, Outstanding			254,289,261
Common Stock, Par or Stated Value Per Share			$ 0.01
Pepco Holdings LLC [Member] | Successor [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets		$ 21,063
[1]	BGE’s consolidated assets include $47 million and $26 million at September 30, 2016 and December 31, 2015, respectively, of BGE’s consolidated VIE that can only be used to settle the liabilities of the VIE. BGE’s consolidated liabilities include $83 million and $122 million at September 30, 2016 and December 31, 2015, respectively, of BGE’s consolidated VIE for which the VIE creditors do not have recourse to BGE. See Note 3 - Variable Interest Entities.

Consolidated Statement of Chang

Consolidated Statement of Changes in Shareholders Equity (Unaudited) - USD ($) shares in Thousands, $ in Millions		Total		Common Stock [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]		Noncontrolling Interest [Member]	Preference Stock Not Subject To Mandatory Redemption [Member]	Exelon Generation Co L L C [Member]		Exelon Generation Co L L C [Member]Undistributed Earnings [Member]	Exelon Generation Co L L C [Member]Accumulated Other Comprehensive Income (Loss) [Member]		Exelon Generation Co L L C [Member]Noncontrolling Interest [Member]	Exelon Generation Co L L C [Member]Membership Interest [Member]	Commonwealth Edison Co [Member]	Commonwealth Edison Co [Member]Common Stock [Member]	Commonwealth Edison Co [Member]Retained Earnings, Unappropriated [Member]	Commonwealth Edison Co [Member]Retained Earnings, Appropriated [Member]	Commonwealth Edison Co [Member]Other Additional Capital [Member]	PECO Energy Co [Member]		PECO Energy Co [Member]Common Stock [Member]	PECO Energy Co [Member]Retained Earnings [Member]	PECO Energy Co [Member]Accumulated Other Comprehensive Income (Loss) [Member]	Baltimore Gas and Electric Company [Member]	Baltimore Gas and Electric Company [Member]Common Stock [Member]	Baltimore Gas and Electric Company [Member]Retained Earnings [Member]	Baltimore Gas and Electric Company [Member]Preferred Stock [Member]	Pepco Holdings LLC [Member]	Pepco Holdings LLC [Member]Additional Paid-in Capital [Member]	Pepco Holdings LLC [Member]Common Stock [Member]	Pepco Holdings LLC [Member]Retained Earnings [Member]	Pepco Holdings LLC [Member]Accumulated Other Comprehensive Income (Loss) [Member]	Pepco Holdings LLC [Member]Common Stock Including Additional Paid in Capital [Member]	Pepco Holdings LLC [Member]Membership Interest [Member]	Potomac Electric Power Company [Member]	Potomac Electric Power Company [Member]Common Stock [Member]	Potomac Electric Power Company [Member]Retained Earnings [Member]	Delmarva Power and Light Company [Member]	Delmarva Power and Light Company [Member]Common Stock [Member]	Delmarva Power and Light Company [Member]Retained Earnings [Member]	Atlantic City Electric Company [Member]	Atlantic City Electric Company [Member]Common Stock [Member]	Atlantic City Electric Company [Member]Retained Earnings [Member]	Pepco Holdings LLC [Member]	Pepco Holdings LLC [Member]Common Stock Including Additional Paid in Capital [Member]	Deferred Compensation, Share-based Payments [Member]Pepco Holdings LLC [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accumulated other comprehensive loss, net	[1]	$ (2,684)									$ (36)												$ 1
Other Comprehensive Income (Loss), Net of Tax | Predecessor [Member]																																$ 5
Other Comprehensive Income (Loss), Net of Tax	[1]	88									(24)												0
Net income | Predecessor [Member]																																197
Net income		1,959									1,208							$ 339					299					$ 212											$ 128			$ 55			$ 37
Proceeds from Contributions from Parent | Predecessor [Member]																																0
Proceeds from Contributions from Parent																		75					16					6											112			75			0
Payments to Acquire Businesses, Gross		(28)									(28)
Ending Balance (Predecessor [Member]) at Dec. 31, 2015																																4,413					$ 3,832
Ending Balance at Dec. 31, 2015		$ 27,294		$ 18,676	$ (2,327)	$ 12,068	$ (2,624)		$ 1,308	$ 193																		2,877											2,240
Ending Balance (in shares) at Dec. 31, 2015		954,668
Ending Balance at Dec. 31, 2015		$ 25,793																8,243	$ 1,588	$ (1,639)	$ 2,617	$ 5,677	3,236		$ 2,455	$ 780	$ 1	2,687	$ 1,367	$ 1,320	$ 190								2,240	$ 1,122	$ 1,118	1,237	$ 612	$ 625	1,000	$ 773	$ 227
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax | Predecessor [Member]																																1
Other Comprehensive Income (Loss), Net of Tax		32									(13)
Net income | Predecessor [Member]																																91
Net income		587									332							149					90					54											60			15			22
Accumulated other comprehensive loss, net	[1]	(2,596)									(60)												1
Common Stock, Value, Issued | Predecessor [Member]																																		$ 3
Common Stock, Value, Issued		18,676																1,588					2,455					1,367											1,122			612			773
Beginning Balance | Predecessor [Member]																																3,832
Beginning Balance											8,997						$ 8,997
Retained Earnings (Accumulated Deficit) | Predecessor [Member]																																617			$ 617
Retained Earnings (Accumulated Deficit)		12,068									2,701		$ 2,701					978					780					1,320														625			227
Accumulated other comprehensive loss, net | Predecessor [Member]																																(36)				$ (36)
Accumulated other comprehensive loss, net		(2,624)	[1]								(63)	[1]		$ (63)		$ 1,307							1	[1]
Limited Liability Company (LLC) Members' Equity, Including Portion Attributable to Noncontrolling Interest											12,942
Additional Paid in Capital | Predecessor [Member]																																	$ 3,829
Additional Paid in Capital																		5,677																					1,118
Derivative Asset, Noncurrent | Predecessor [Member]																																0
Derivative Asset, Noncurrent		$ 758									733
Other Comprehensive Income (Loss), Net of Tax | Predecessor [Member]																																1				1
Stock Issued During Period, Value, Employee Stock Purchase Plan | Predecessor [Member]																																3					3
Net income | Predecessor [Member]																																19			19
Employee stock purchase plan issuances | Predecessor [Member]																																3					3
Ending Balance (Predecessor [Member]) at Mar. 23, 2016																																4,439			636	(35)	3,838
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from Contributions from Parent | Predecessor [Member]																																0
Beginning Balance (in shares) at Dec. 31, 2015		954,668
Beginning Balance (Predecessor [Member]) at Dec. 31, 2015																																4,413					3,832
Beginning Balance at Dec. 31, 2015		$ 27,294		18,676	(2,327)	12,068	(2,624)		1,308	193																		2,877											2,240
Beginning Balance at Dec. 31, 2015		25,793																8,243	1,588	(1,639)	2,617	5,677	3,236		2,455	780	1	2,687	1,367	1,320	190								2,240	1,122	1,118	1,237	612	625	1,000	773	227
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax		96					101	[1]			2		0	7	[1]	(5)
Net Working Capital		96		0	0	0			(5)	0
Stock Issued During Period, Value, Employee Stock Purchase Plan		$ 36		36	0	0	0		0	0
Stock Issued During Period, Shares, Employee Stock Purchase Plans		924
Net income		$ 956		0	0	930	0		18	8	556		538	0		18		297		297			346			346		191		191									20		20	(16)		(16)	(50)		(50)	$ (92)
Distribution Made to Limited Liability Company (LLC) Member, Cash Distributions Declared											(167)		(167)															(7)	(7)	0
Noncontrolling Interest, Increase from Sale of Parent Equity Interest											105
Long-term incentive plan activity (in shares)		2,422
Long-term incentive plan activity		$ 61		61	0	0	0		0	0
Employee stock purchase plan issuances (in shares)		924
Employee stock purchase plan issuances		$ 36		36	0	0	0		0	0
Appropriation of retained earnings for future dividends																		0		(297)	297
Tax benefit on stock compensation		(17)		(17)	0	0	0		0	0
Common stock dividends		(877)		0	0	(877)	0		0	(8)								(275)			(275)		(208)			(208)		(134)		(134)												(39)		(39)	(24)		(24)
Contribution from parent											170						170	188				188						28	28	0									187	187		113	113		139	139
Dividends																																							(125)		(125)
Allocation of tax benefit from parent																		157				157	18
Minority Interest Increase From Acquisition		5		0	0	0	0		5	0	5					5
Preferred security dividends		(8)																										(8)		(8)	0
Temporary Equity, Other Changes		(107)		0	0	0	0		(107)	0	107					(107)
Allocation Of Tax Benefit From Members											98						98
Ending Balance at Sep. 30, 2016		$ 27,460		18,756	(2,327)	12,121	(2,523)		1,433	0																		2,757											2,322
Ending Balance (in shares) at Sep. 30, 2016		958,014
Ending Balance at Sep. 30, 2016		$ 26,027																8,610	1,588	(1,639)	2,639	6,022	3,392		2,473	918	1	2,757	1,388	1,369	0								2,322	1,309	1,013	1,295	725	570	1,065	912	153
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from Contributions from Parent																		188					18					28											187			113			139
Payments to Acquire Businesses, Gross | Successor [Member]																																							(33)
Payments to Acquire Businesses, Gross		(6,896)									(255)																																							$ (29)
Common Stock, Value, Issued | Predecessor [Member]																																3		$ 3			3
Additional Paid in Capital | Predecessor [Member]																																	$ 3,835
Payments to Acquire Businesses, Gross | Successor [Member]																																																(33)
Beginning Balance | Successor [Member]																																7,200					7,200
Retained Earnings (Accumulated Deficit) | Successor [Member]																																			0
Accumulated other comprehensive loss, net | Successor [Member]																																				0
Limited Liability Company (LLC) Members' Equity, Including Portion Attributable to Noncontrolling Interest | Successor [Member]																																7,200
Business Combination, Contingent Consideration, Asset | Successor [Member]																																(301)					235
Business Combination, Contingent Consideration, Liability, Noncurrent | Successor [Member]																																53					53
Other Comprehensive Income (Loss), Net of Tax | Successor [Member]																																0
Net income | Successor [Member]																																(91)			(91)			$ 0
Distribution Made to Limited Liability Company (LLC) Member, Cash Distributions Declared | Successor [Member]																																					66
Contribution from parent | Successor [Member]																																1,088					1,088
Ending Balance at Sep. 30, 2016		$ 27,460		18,756	(2,327)	12,121	(2,523)		1,433	0																		2,757											2,322
Ending Balance (in shares) at Sep. 30, 2016		958,014
Ending Balance at Sep. 30, 2016		$ 26,027																8,610	1,588	(1,639)	2,639	6,022	3,392		2,473	918	1	2,757	1,388	1,369	0								2,322	1,309	1,013	1,295	725	570	1,065	912	153
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from Contributions from Parent | Successor [Member]																																1,088
Payments to Acquire Businesses, Gross | Successor [Member]																																																(62)	$ (62)	$ (29)
Other Comprehensive Income (Loss), Net of Tax | Successor [Member]																																0
Other Comprehensive Income (Loss), Net of Tax		36									4
Net income | Successor [Member]																																166
Net income		526									271							37					122					56											79			44			47			$ 169
Ending Balance at Sep. 30, 2016		$ 27,460		$ 18,756	$ (2,327)	$ 12,121	$ (2,523)		$ 1,433	0																		2,757											2,322
Ending Balance (in shares) at Sep. 30, 2016		958,014
Ending Balance at Sep. 30, 2016		$ 26,027																8,610	$ 1,588	$ (1,639)	$ 2,639	$ 6,022	3,392		$ 2,473	$ 918	$ 1	2,757	$ 1,388	$ 1,369	0								2,322	$ 1,309	$ 1,013	1,295	$ 725	$ 570	1,065	$ 912	$ 153
Common Stock, Value, Issued		18,756																1,588					2,473					1,388											1,309			725			912
Preferred Stock, Redemption Amount		193								$ 193																		(190)			$ (190)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance | Successor [Member]																																7,978					7,978
Beginning Balance											9,265						$ 9,265
Retained Earnings (Accumulated Deficit) | Successor [Member]																																(91)			$ (91)
Retained Earnings (Accumulated Deficit)		12,121									3,072		$ 3,072					1,000					918					$ 1,369														$ 570			$ 153
Accumulated other comprehensive loss, net | Successor [Member]																																0				$ 0
Accumulated other comprehensive loss, net		(2,523)	[1]								(56)	[1]		$ (56)		$ 1,432							$ 1	[1]
Limited Liability Company (LLC) Members' Equity, Including Portion Attributable to Noncontrolling Interest | Successor [Member]																																7,887
Limited Liability Company (LLC) Members' Equity, Including Portion Attributable to Noncontrolling Interest											13,713
Business Combination, Contingent Consideration, Asset | Successor [Member]																																					$ (301)
Business Combination, Contingent Consideration, Asset		(235)									(163)
Additional Paid in Capital																		$ 6,022																					$ 1,013
Derivative Asset, Noncurrent | Successor [Member]																																$ 0
Derivative Asset, Noncurrent		$ 669									$ 630
[1]	All amounts are net of tax and noncontrolling interest. Amounts in parenthesis represent a decrease in AOCI.

Consolidated Statement of Chan7

Consolidated Statement of Changes in Shareholders Equity (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income taxes	$ 340	$ 115	$ 625	$ 805
Exelon Generation Co L L C [Member]
Income taxes	173	(36)	293	371
Atlantic City Electric Company [Member]
Income taxes	23	14	(8)	23
PECO Energy Co [Member]
Income taxes	54	37	121	122
Commonwealth Edison Co [Member]
Income taxes	75	99	244	226
Baltimore Gas and Electric Company [Member]
Income taxes	36	35	109	141
Potomac Electric Power Company [Member]
Income taxes	$ 35	$ 32	$ 34	$ 62

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation (Exelon, Generation, ComEd, PECO and BGE)	1 . Significant Accounting Policies (All Registrants) Description of Business (All Registrants) Exelon is a utility services holding company engaged through its principal subsidiaries in the energy generation and energy distribution and transmission businesses. Prior to March 23, 2016 , Exelon's principal, wholly owned subsidiaries included Generation, ComEd, PECO and BGE. On March 23, 2016 , in conjunction with the Amended and Restated Agreement and Plan of Merger (the PHI Merger Agreement), Purple Acquisition Corp, a wholly owned subsidiary of Exelon, merged with and into PHI, with PHI continuing as the surviving entity as a wholly owned subsidiary of Exelon. PHI is a utility services holding company engaged through its principal wholly owned subsidiaries, Pepco, DPL and ACE, in the energy distribution and transmission businesses. Refer to Note 4 - Mergers, Acquisitions and Dispositions for further information regarding the merger transaction. The energy generation business includes: • Generation : Generation, physical delivery and marketing of power across multiple geographical regions through its customer-facing business, Constellation, which sells electricity and natural gas to both wholesale and retail customers. Generation also sells renewable energy and other energy-related products and services. Generation has six reportable segments consisting of the Mid-Atlantic, Midwest, New England, New York, ERCOT and Other Power Regions. The energy delivery businesses include: • ComEd : Purchase and regulated retail sale of electricity and the provision of electric distribution and transmission services in northern Illinois, including the City of Chicago. • PECO : Purchase and regulated retail sale of electricity and the provision of electric distribution and transmission services in southeastern Pennsylvania, including the City of Philadelphia, and the purchase and regulated retail sale of natural gas and the provision of natural gas distribution services in the Pennsylvania counties surrounding the City of Philadelphia. • BGE : Purchase and regulated retail sale of electricity and the provision of electric distribution and transmission services in central Maryland, including the City of Baltimore, and the purchase and regulated retail sale of natural gas and the provision of natural gas distribution services in central Maryland, including the City of Baltimore. • Pepco : Purchase and regulated retail sale of electricity and the provision of electric distribution and transmission services in the District of Columbia and major portions of Prince George's County and Montgomery County in Maryland. • DPL : Purchase and regulated retail sale of electricity and the provision of electric distribution and transmission services in portions of Maryland and Delaware, and the purchase and regulated retail sale of natural gas and the provision of natural gas distribution services in northern Delaware. • ACE : Purchase and regulated retail sale of electricity and the provision of electric distribution and transmission services in southern New Jersey. Basis of Presentation (All Registrants) Pursuant to the acquisition of PHI, Exelon’s financial reporting reflects PHI’s consolidated financial results subsequent to the March 23, 2016 , acquisition date. Exelon has accounted for the merger transaction applying the acquisition method of accounting, which requires the assets acquired and liabilities assumed by Exelon to be reported in Exelon’s financial statements at fair value, with any excess of the purchase price over the fair value of net assets acquired reported as goodwill. Exelon has pushed-down the application of the acquisition method of accounting to the consolidated financial statements of PHI such that the assets and liabilities of PHI are similarly recorded at their respective fair values, and goodwill has been established as of the acquisition date. Accordingly, the consolidated financial statements of PHI for periods before and after the March 23, 2016 , acquisition date reflect different bases of accounting, and the financial positions and the results of operations of the predecessor and successor periods are not comparable. The acquisition method of accounting has not been pushed down to PHI’s wholly-owned subsidiary utility registrants, Pepco, DPL and ACE. For financial statement purposes, beginning on March 24, 2016 , disclosures that had solely related to PHI, Pepco, DPL or ACE activities now also apply to Exelon, unless otherwise noted. When appropriate, Exelon, Generation, ComEd, PECO, BGE, PHI, Pepco, DPL and ACE are named specifically for their related activities and disclosures. Certain prior year amounts in the Consolidated Statements of Operations and Comprehensive Income, Consolidated Balance Sheets and Consolidated Statements of Cash Flows of PHI, Pepco, DPL and ACE have been reclassified to conform the presentation of these amounts to the current period presentation in Exelon’s financial statements. Most significantly for PHI, Pepco, DPL and ACE, current regulatory assets and liabilities have been presented separately from the non-current portions in each respective Consolidated Balance Sheet where recovery or refund is expected within the next 12 months. Additionally, for PHI, Pepco, DPL and ACE, the removal cost within Accumulated depreciation was reclassified to the Regulatory liability or Regulatory asset account to align with Exelon’s presentation. The reclassifications were not considered errors for PHI, Pepco, DPL or ACE. In its December 31, 2015 Form 10-K, Exelon revised the presentation on the Consolidated Statements of Operations and Comprehensive Income for PECO and BGE to reflect separately operating revenues from the sale of electricity and operating revenues from the sale of natural gas, as well as to reflect separately purchased power expense and purchased fuel expense within the operating expenses section of the Consolidated Statement of Operations and Comprehensive Income. Further, Exelon revised the presentation from Total operating revenues to "Rate-regulated utility revenues" and "Competitive businesses revenues" on the face of Exelon’s Consolidated Statement of Operations and Comprehensive Income for all periods presented. Similarly, Exelon has separately presented Rate-regulated utility purchased power and fuel expense and Competitive businesses purchased power and fuel expense on the face of Exelon’s Consolidated Statement of Operations and Comprehensive Income for all periods presented. The reclassifications described herein were made for presentation purposes and did not affect any of the Registrants’ total operating revenues or net income. ACE Basic Generation Service Recovery Mechanism ACE has a recovery mechanism for purchased power costs associated with BGS. ACE records a deferred energy supply costs regulatory asset or regulatory liability for under or over-recovered costs that are expected to be recovered from or refunded to ACE customers, respectively. In the first quarter of 2016, ACE changed its method of accounting for determining under or over-recovered costs in this recovery mechanism to include unbilled revenues in the determination of under or over-recovered costs. ACE believes this change is preferable as it better reflects the economic impacts of dollar-for-dollar cost recovery mechanisms. ACE applied the change retrospectively. The impact of the change was a $12 million reduction to ACE’s opening Retained earnings as of January 1, 2014 with a corresponding reduction to Regulatory assets. The impact of the change on Net income attributable to common shareholder was an increase of $8 million and $9 million for the three and nine months ended September 30, 2015 , respectively. Classification of Interest on Uncertain Tax Positions In the first quarter of 2016, PHI, Pepco, DPL and ACE changed their accounting principle for classification of interest on uncertain tax positions. PHI, Pepco, DPL and ACE have reclassified interest on uncertain tax positions as interest expense from income tax expense in the Consolidated Statements of Operations and Comprehensive Income. GAAP does not address the preferability of one acceptable method of accounting over the other for the classification of interest on uncertain tax positions. However, PHI, Pepco, DPL, and ACE believe this change is preferable for comparability of their financial statements with the financial statements of the other Registrants in the combined filing, for consistency with FERC classification, and for a more appropriate representation of the effective tax rate as they manage the settlement of uncertain tax positions and interest expense separately. PHI, Pepco, DPL, and ACE applied the change retrospectively. The reclassification in the Consolidated Statements of Operations and Comprehensive Income for the nine months ended September 30, 2015 is $1 million for PHI and less than $1 million for Pepco, DPL and ACE. The reclassification amount is more significant for the year ended December 31, 2015. Each of the Registrant’s Consolidated Financial Statements includes the accounts of its subsidiaries. All intercompany transactions have been eliminated. The accompanying consolidated financial statements as of September 30, 2016 and 2015 and for the three and nine months then ended are unaudited but, in the opinion of the management of each Registrant include all adjustments that are considered necessary for a fair statement of the Registrants’ respective financial statements in accordance with GAAP. All adjustments are of a normal, recurring nature, except as otherwise disclosed. The December 31, 2015 Consolidated Balance Sheets were obtained from audited financial statements. Financial results for interim periods are not necessarily indicative of results that may be expected for any other interim period or for the fiscal year ending December 31, 2016 . These Combined Notes to Consolidated Financial Statements have been prepared pursuant to the rules and regulations of the SEC for Quarterly Reports on Form 10-Q. Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations.

Variable Interest Entities (All

Variable Interest Entities (All Registrants)	9 Months Ended
	Sep. 30, 2016
Variable Interest Entity [Abstract]
Variable Interest Entity Disclosure (All Registrants)	3 . Variable Interest Entities (All Registrants) A VIE is a legal entity that possesses any of the following characteristics: an insufficient amount of equity at risk to finance its activities, equity owners who do not have the power to direct the significant activities of the entity (or have voting rights that are disproportionate to their ownership interest), or equity owners who do not have the obligation to absorb expected losses or the right to receive the expected residual returns of the entity. Companies are required to consolidate a VIE if they are its primary beneficiary, which is the enterprise that has the power to direct the activities that most significantly affect the entity’s economic performance. At September 30, 2016 , Exelon, Generation, BGE, PHI and ACE collectively consolidated nine VIEs or VIE groups for which the applicable Registrant was the primary beneficiary. At December 31, 2015 , Exelon, Generation and BGE collectively had seven consolidated VIEs or VIE groups and PHI and ACE collectively had one consolidated VIE ( see Consolidated Variable Interest Entities below) . As of September 30, 2016 and December 31, 2015 , Exelon and Generation collectively had significant interests in nine and eight other VIEs, respectively, for which the applicable Registrant does not have the power to direct the entities' activities and, accordingly, was not the primary beneficiary (see Unconsolidated Variable Interest Entities below) . Consolidated Variable Interest Entities In June 2015, 2015 ESA Investco, LLC, then a wholly owned subsidiary of Generation, entered into an arrangement to purchase a 90% equity interest and 99% of the tax attributes of another distributed energy company. In November 2015, Generation sold 69% of its equity interest in 2015 ESA Investco, LLC to a tax equity investor. Generation and the tax equity investor will contribute up to a total of $250 million of equity incrementally from inception through December 2016 in proportion to their ownership interests, which equates up to approximately $172 million for the tax equity investor and up to $78 million for Generation (see Note 18 — Commitments and Contingencies for more details). The investment in the distributed energy company was evaluated, and it was determined to be a VIE for which Generation is not the primary beneficiary (see additional details in the Unconsolidated Variable Interest Entities section below). As of December 31, 2015, Generation consolidated 2015 ESA Investco, LLC under the voting interest model. However, pursuant to the new consolidation guidance effective as of January 1, 2016 for the Registrants, 2015 ESA Investco, LLC meets the definition of a VIE because the company has a similar structure to a limited partnership and the limited partners do not have kick out rights with respect to the general partner. (For additional details related to the new consolidation guidance, see Note 2 — New Accounting Pronouncements .) Under VIE guidance, Generation is the primary beneficiary; therefore, the entity continues to be consolidated. Exelon's, Generation's, BGE's, PHI's and ACE's consolidated VIEs consist of: • A retail gas group formed by Generation to enter into a collateralized gas supply agreement with a third-party gas supplier, • a group of solar project limited liability companies formed by Generation to build, own and operate solar power facilities, • several wind project companies designed by Generation to develop, construct and operate wind generation facilities, • a group of companies formed by Generation to build, own and operate other generating facilities, • certain retail power and gas companies for which Generation is the sole supplier of energy, • CENG, • 2015 ESA Investco, LLC, • BondCo, a special purpose bankruptcy remote limited liability company formed by BGE to acquire, hold, issue and service bonds secured by rate stabilization property, and • ATF , a special purpose entity formed by ACE for the purpose of securitizing authorized portions of ACE’s recoverable stranded costs through the issuance and sale of transition bonds. As of September 30, 2016 and December 31, 2015 , ComEd, PECO, Pepco and DPL did not have any material consolidated VIEs. As of September 30, 2016 and December 31, 2015 , Exelon, Generation, BGE, PHI and ACE provided the following support to their respective consolidated VIEs: • Generation provides operating and capital funding to the solar and wind entities for ongoing construction, operations and maintenance of the solar and wind power facilities and there is limited recourse to Generation related to certain solar and wind entities. • Generation and Exelon, where indicated, provide the following support to CENG (see Note 5 — Investment in Constellation Energy Nuclear Group, LLC and Note 26 — Related Party Transactions of the Exelon 2015 Form 10-K for additional information regarding Generation's and Exelon’s transactions with CENG): • under the NOSA, Generation conducts all activities related to the operation of the CENG nuclear generation fleet owned by CENG subsidiaries (the CENG fleet) and provides corporate and administrative services for the remaining life and decommissioning of the CENG nuclear plants as if they were a part of the Generation nuclear fleet, subject to the CENG member rights of EDF, • under the Power Services Agency Agreement (PSAA), Generation provides scheduling, asset management, and billing services to the CENG fleet for the remaining operating life of the CENG nuclear plants, • under power purchase agreements with CENG, Generation purchased or will purchase 50.01% of the available output generated by the CENG nuclear plants not subject to other contractual agreements from January 2015 through the end of the operating life of each respective plant. However, pursuant to amendments dated March 31, 2015, the energy obligations under the Ginna Nuclear Power Plant (Ginna) PPAs have been suspended during the term of the Reliability Support Services Agreement (RSSA) (see Note 5 — Regulatory Matters for additional details), • Generation provided a $400 million loan to CENG. As of September 30, 2016 , the remaining obligation is $312 million , including accrued interest, which reflects the principal payment made in January 2015, • Generation executed an Indemnity Agreement pursuant to which Generation agreed to indemnify EDF against third-party claims that may arise from any future nuclear incident (as defined in the Price-Anderson Act) in connection with the CENG nuclear plants or their operations. Exelon guarantees Generation’s obligations under this Indemnity Agreement. (See Note 18 — Commitments and Contingencies for more details), • in connection with CENG’s severance obligations, Generation has agreed to reimburse CENG for a total of approximately $6 million of the severance benefits paid or to be paid in 2014 through 2016. As of September 30, 2016 , there was no remaining obligation, • Generation and EDF share in the $637 million of contingent payment obligations for the payment of contingent retrospective premium adjustments for the nuclear liability insurance, • Generation provides a guarantee of approximately $8 million associated with hazardous waste management facilities and underground storage tanks. In addition, EDF executed a reimbursement agreement that provides reimbursement to Exelon for 49.99% of any amounts paid by Generation under this guarantee, • Generation and EDF are the members-insured with Nuclear Electric Insurance Limited and have assigned the loss benefits under the insurance and the NEIL premium costs to CENG and guarantee the obligations of CENG under these insurance programs in proportion to their respective member interests (see Note 18 — Commitments and Contingencies for more details), and • Exelon has executed an agreement to provide up to $245 million to support the operations of CENG as well as a $165 million guarantee of CENG’s cash pooling agreement with its subsidiaries. • Generation provides approximately $16 million in credit support for the retail power and gas companies for which Generation is the sole supplier of energy. • Generation provides a $75 million parental guarantee to a third-party gas supplier and provides limited recourse to other third-party gas suppliers and customers in support of its retail gas group. • Generation provides operating and capital funding to the other generating facilities for ongoing construction, operations and maintenance and provides a parental guarantee of up to $275 million in support of the payment obligations related to the Engineering, Procurement and Construction contract in support of one of its other generating facilities. • In the case of BondCo, BGE is required to remit all payments it receives from all residential customers through non-bypassable, rate stabilization charges to BondCo. During the three and nine months ended September 30, 2016 , BGE remitted $27 million and $64 million to BondCo, respectively. During the three and nine months ended September 30, 2015 , BGE remitted $21 million and $63 million to BondCo, respectively. • In the case of ATF, proceeds from the sale of each series of transition bonds by ATF were transferred to ACE in exchange for the transfer by ACE to ATF of the right to collect a non-bypassable Transition Bond Charge from ACE customers pursuant to bondable stranded costs rate orders issued by the NJBPU in an amount sufficient to fund the principal and interest payments on transition bonds and related taxes, expenses and fees. During the three and nine months ended September 30, 2016 , ACE transferred $20 million and $47 million to ATF, respectively. During the three and nine months ended September 30, 2015 , ACE transferred $18 million and $45 million to ATF, respectively. For each of the consolidated VIEs, except as otherwise noted: • the assets of the VIEs are restricted and can only be used to settle obligations of the respective VIE; • Exelon, Generation, BGE, PHI and ACE did not provide any additional material financial support to the VIEs; • Exelon, Generation, BGE, PHI and ACE did not have any material contractual commitments or obligations to provide financial support to the VIEs; and • the creditors of the VIEs did not have recourse to Exelon’s, Generation’s, BGE’s, PHI's or ACE's general credit. The carrying amounts and classification of the consolidated VIEs’ assets and liabilities included in the Registrants' consolidated financial statements at September 30, 2016 and December 31, 2015 are as follows: September 30, 2016 December 31, 2015 Successor Predecessor Exelon (a)(b) Generation BGE PHI (b) ACE Exelon (a) Generation BGE PHI ACE Current assets $ 914 $ 849 $ 44 $ 20 $ 15 $ 909 $ 881 $ 23 $ 12 $ 12 Noncurrent assets 8,235 8,201 3 31 19 8,009 8,004 3 18 18 Total assets $ 9,149 $ 9,050 $ 47 $ 51 $ 34 $ 8,918 $ 8,885 $ 26 $ 30 $ 30 Current liabilities $ 569 $ 439 $ 84 45 $ 40 $ 473 $ 387 $ 81 $ 48 $ 48 Noncurrent liabilities 3,090 2,979 — 111 99 2,927 2,884 41 124 124 Total liabilities $ 3,659 $ 3,418 $ 84 $ 156 $ 139 $ 3,400 $ 3,271 $ 122 $ 172 $ 172 _______ (a) Includes certain purchase accounting adjustments not pushed down to the BGE standalone entity. (b) Includes certain purchase accounting adjustments not pushed down to the ACE standalone entity. Assets and Liabilities of Consolidated VIEs Included within the balances above are assets and liabilities of certain consolidated VIEs for which the assets can only be used to settle obligations of those VIEs, and liabilities that creditors, or beneficiaries, do not have recourse to the general credit of the Registrants. As of September 30, 2016 and December 31, 2015 , these assets and liabilities primarily consisted of the following: September 30, 2016 December 31, 2015 Successor Predecessor Exelon (a)(b) Generation BGE PHI (b) ACE Exelon (a) Generation BGE PHI ACE Cash and cash equivalents $ 160 $ 160 $ — $ — $ — $ 164 $ 164 $ — $ — $ — Restricted cash 101 43 44 15 15 100 77 23 12 12 Accounts receivable, net Customer 264 264 — — — 219 219 — — — Other 42 42 — — — 43 43 — — — Mark-to-market derivatives assets 49 49 — — — 140 140 — — — Inventory Materials and supplies 192 192 — — — 181 181 — — — Other current assets 58 51 — 5 — 35 30 — — — Total current assets 866 801 44 20 15 882 854 23 12 12 Property, plant and equipment, net 5,139 5,139 — — — 5,160 5,160 — — — Nuclear decommissioning trust funds 2,173 2,173 — — — 2,036 2,036 — — — Goodwill 47 47 — — — 47 47 — — — Mark-to-market derivatives assets 32 32 — — — 53 53 — — — Other noncurrent assets 257 223 3 31 19 90 85 3 18 18 Total noncurrent assets 7,648 7,614 3 31 19 7,386 7,381 3 18 18 Total assets $ 8,514 $ 8,415 $ 47 $ 51 $ 34 $ 8,268 $ 8,235 $ 26 $ 30 $ 30 Long-term debt due within one year $ 191 $ 64 $ 81 $ 43 $ 38 $ 111 $ 27 $ 79 $ 46 $ 46 Accounts payable 201 201 — — — 216 216 — — — Accrued expenses 102 98 2 2 2 115 113 2 2 2 Mark-to-market derivative liabilities 24 24 — — — 5 5 — — — Unamortized energy contract liabilities 14 14 — — — 12 12 — — — Other current liabilities 34 34 — — — 13 13 — — — Total current liabilities 566 435 83 45 40 472 386 81 48 48 Long-term debt 661 550 — 111 99 666 623 41 124 124 Asset retirement obligations 2,070 2,070 — — — 1,999 1,999 — — — Pension obligation (c) 9 9 — — — 9 9 — — — Unamortized energy contract liabilities 26 26 — — — 39 39 — — — Other noncurrent liabilities 106 106 — — — 79 79 — — — Total noncurrent liabilities 2,872 2,761 — 111 99 2,792 2,749 41 124 124 Total liabilities $ 3,438 $ 3,196 $ 83 $ 156 $ 139 $ 3,264 $ 3,135 $ 122 $ 172 $ 172 _______ (a) Includes certain purchase accounting adjustments not pushed down to the BGE standalone entity. (b) Includes certain purchase accounting adjustments not pushed down to the ACE standalone entity. (c) Includes the CNEG retail gas pension obligation, which is presented as a net asset balance within the Prepaid pension asset line item on Generation’s balance sheet. See Note 13 - Retirement Benefits for additional details. Unconsolidated Variable Interest Entities Exelon’s and Generation’s variable interests in unconsolidated VIEs generally include equity investments and energy purchase and sale contracts. For the equity investments, the carrying amount of the investments is reflected on Exelon’s and Generation’s Consolidated Balance Sheets in Investments. For the energy purchase and sale contracts (commercial agreements), the carrying amount of assets and liabilities in Exelon’s and Generation’s Consolidated Balance Sheets that relate to their involvement with the VIEs are predominately related to working capital accounts and generally represent the amounts owed by, or owed to, Exelon and Generation for the deliveries associated with the current billing cycles under the commercial agreements. Further, Exelon and Generation have not provided material debt or equity support, liquidity arrangements or performance guarantees associated with these commercial agreements. The Registrants’ unconsolidated VIEs consist of: • Energy purchase and sale agreements with VIEs for which Generation has concluded that consolidation is not required. • Asset sale agreement with ZionSolutions, LLC and EnergySolutions, Inc. in which Generation has a variable interest but has concluded that consolidation is not required. • Equity investments in energy development companies, distributed energy companies, and energy generating facilities for which Generation has concluded that consolidation is not required. As of September 30, 2016 and December 31, 2015 , Exelon and Generation had significant unconsolidated variable interests in nine and eight VIEs, respectively for which Exelon or Generation, as applicable, was not the primary beneficiary; including certain equity investments and certain commercial agreements. Exelon and Generation only include unconsolidated VIEs that are individually material in the tables below. However, Generation has several individually immaterial VIEs that in aggregate represent a total investment of $20 million . These immaterial VIEs are equity and debt securities in energy development companies. The maximum exposure to loss related to these securities is limited to the $20 million included in Investments on Exelon’s and Generation’s Consolidated Balance Sheets . The risk of a loss was assessed to be remote and, accordingly, Exelon and Generation have not recognized a liability associated with any portion of the maximum exposure to loss. In July 2014, Generation entered into an arrangement to purchase a 90% equity interest and 90% of the tax attributes of a distributed energy company. Generation’s total equity commitment in this arrangement was $91 million and was paid incrementally over an approximate two year period (see Note 18 — Commitments and Contingencies for additional details). This arrangement did not meet the definition of a VIE and was recorded as an equity method investment. However, pursuant to the new consolidation guidance effective as of January 1, 2016 for the Registrants, the distributed energy company meets the definition of a VIE because the company has a similar structure to a limited partnership and the limited partners do not have kick out rights of the general partner. (For additional details related to the new consolidation guidance, see Note 2 — New Accounting Pronouncements .) Generation is not the primary beneficiary; therefore, the investment continues to be recorded using the equity method. In June 2015, 2015 ESA Investco, LLC, then a wholly owned subsidiary of Generation, entered into an arrangement to purchase a 90% equity interest and 99% of the tax attributes of a distributed energy company, which is an unconsolidated VIE. Separate from the equity investment, Generation provided $27 million in cash to the other (10%) equity holder in the distributed energy company in exchange for a convertible promissory note. In November 2015, Generation sold 69% of its equity interest in 2015 ESA Investco, LLC to a tax equity investor. Generation and the tax equity investor will contribute up to a total of $250 million of equity incrementally from inception through December 2016 in proportion of their ownership interests, which equates up to approximately $172 million for the tax equity investor and up to $78 million for Generation (see Note 18 — Commitments and Contingencies for additional details). Generation and the tax equity investor provide a parental guarantee of up to $275 million in proportion to their ownership interests in support of 2015 ESA Investco, LLC's obligation to make equity contributions to the distributed energy company, which is an unconsolidated VIE. The investment in the distributed energy company was evaluated and it was determined to be a VIE for which Generation is not the primary beneficiary. See additional details in the Consolidated Variable Interest Entities section above. The following tables present summary information about Exelon and Generation’s significant unconsolidated VIE entities: September 30, 2016 Commercial Agreement VIEs Equity Investment VIEs Total Total assets (a) $ 586 $ 531 $ 1,117 Total liabilities (a) 181 308 489 Exelon's ownership interest in VIE (a) — 193 193 Other ownership interests in VIE (a) 405 34 439 Registrants’ maximum exposure to loss: Carrying amount of equity method investments — 225 225 Contract intangible asset 9 — 9 Debt and payment guarantees — 3 3 Net assets pledged for Zion Station decommissioning (b) 11 — 11 December 31, 2015 Commercial Agreement VIEs Equity Investment VIEs Total Total assets (a) $ 263 $ 164 $ 427 Total liabilities (a) 22 125 147 Exelon's ownership interest in VIE (a) — 11 11 Other ownership interests in VIE (a) 241 28 269 Registrants’ maximum exposure to loss: Carrying amount of equity method investments — 21 21 Contract intangible asset 9 — 9 Debt and payment guarantees — 3 3 Net assets pledged for Zion Station decommissioning (b) 17 — 17 _______ (a) These items represent amounts on the unconsolidated VIE balance sheets, not on Exelon’s or Generation’s Consolidated Balance Sheets. These items are included to provide information regarding the relative size of the unconsolidated VIEs. (b) These items represent amounts on Exelon’s and Generation’s Consolidated Balance Sheets related to the asset sale agreement with ZionSolutions, LLC. The net assets pledged for Zion Station decommissioning includes gross pledged assets of $135 million and $206 million as of September 30, 2016 and December 31, 2015 , respectively; offset by payables to ZionSolutions LLC of $124 million and $189 million as of September 30, 2016 and December 31, 2015 , respectively. These items are included to provide information regarding the relative size of the ZionSolutions LLC unconsolidated VIE. For each of the unconsolidated VIEs, Exelon and Generation has assessed the risk of a loss equal to their maximum exposure to be remote and, accordingly, Exelon and Generation have not recognized a liability associated with any portion of the maximum exposure to loss. In addition, there are no material agreements with, or commitments by, third parties that would affect the fair value or risk of their variable interests in these VIEs.

Mergers, Acquisitions, and Disp

Mergers, Acquisitions, and Dispositions	9 Months Ended
	Sep. 30, 2016
Business Combinations [Abstract]
Mergers, Acquisitions and Dispositions	Mergers, Acquisitions and Dispositions (Exelon, Generation, PHI and Pepco) Merger with Pepco Holdings, Inc. (Exelon) Description of Transaction On March 23, 2016 , Exelon completed the merger contemplated by the Merger Agreement among Exelon, Purple Acquisition Corp., a wholly owned subsidiary of Exelon (Merger Sub) and Pepco Holdings, Inc. (PHI). As a result of that merger, Merger Sub was merged into PHI (the PHI Merger) with PHI surviving as a wholly owned subsidiary of Exelon and Exelon Energy Delivery Company, LLC (EEDC), a wholly owned subsidiary of Exelon which also owns Exelon's interests in ComEd, PECO and BGE (through a special purpose subsidiary in the case of BGE). Following the completion of the PHI Merger, Exelon and PHI completed a series of internal corporate organization restructuring transactions resulting in the transfer of PHI’s unregulated business interests to Exelon and Generation and the transfer of PHI, Pepco, DPL and ACE to a special purpose subsidiary of EEDC. Regulatory Matters Approval of the merger in Delaware, New Jersey, Maryland and the District of Columbia was conditioned upon Exelon and PHI agreeing to certain commitments including where applicable: customer rate credits, funding for energy efficiency and delivery system modernization programs, a green sustainability fund, workforce development initiatives, charitable contributions, renewable generation and other required commitments. In addition, the orders approving the merger in Delaware, New Jersey, and Maryland include a “most favored nation” provision which, generally speaking, requires allocation of merger benefits proportionally across all the jurisdictions. In the first quarter of 2016, Exelon estimated and recorded total nominal cost commitments of $508 million , excluding renewable generation commitments (approximately $444 million on a net present value basis, excluding renewable generation commitments and charitable contributions). During the third and fourth quarters of 2016, Exelon and PHI filed proposals in Delaware and New Jersey and continued negotiations in Maryland for amounts and allocations reflecting the application of the most favored nation provision, resulting in total nominal cost of commitments of $513 million , excluding renewable generation commitments(with no change in the $444 million net present value basis amount, excluding renewable generation commitments and charitable contributions). A similar filing will be required in Maryland. These filings, which reflect agreements reached with certain parties to the merger proceedings in the jurisdictions, are subject to regulatory review and approval in each jurisdiction. The Delaware Commission approved the amounts and allocations in September and October 2016 and an order from the New Jersey BPU is expected in the fourth quarter of 2016. No changes in commitment cost levels are required in the District of Columbia. The proposed settlements included certain changes in the amount and mix of previously reported, expected commitment types, resulting in adjustments to the estimated commitment costs recorded by Exelon Corporate and by the individual PHI utility reporting entities such that more commitments are expected to be obligations of Exelon Corporate for energy efficiency, workforce development and other programs as opposed to obligations of PHI, Pepco, DPL and ACE for additional customer rate credits. Specifically, for the three months ended September 30, 2016 , Exelon Corporate recorded an increase of $55 million and PHI, Pepco, DPL and ACE recorded decreases of $ 50 million , $13 million , $27 million and $10 million , respectively, in Operating and maintenance expense. The following amounts were recognized as total commitment costs in Operating and maintenance expense in Exelon's, PHI's, Pepco's, DPL's and ACE's Consolidated Statements of Operations and Comprehensive Income for the nine months ended September 30, 2016 and PHI's successor period: Expected Payment Period Successor Description Pepco (a) DPL (a) ACE (a) PHI (a) Exelon (a) Rate credits 2016 - 2017 $ 91 $ 58 $ 101 $ 250 $ 250 Energy efficiency 2016 - 2021 — — — — 120 Charitable contributions 2016 - 2026 28 12 10 50 50 Delivery system modernization Q2 2016 — — — — 22 Green sustainability fund Q2 2016 — — — — 14 Workforce development 2016 - 2020 — — — — 24 Other 7 7 — 14 33 Total $ 126 $ 77 $ 111 $ 314 $ 513 _______ (a) Included within the individual line items is the most favored nation provision estimate of $6 million , $5 million $38 million , $49 million , and $134 million at Pepco, DPL, ACE, PHI and Exelon, respectively. Pursuant to the orders approving the merger, Exelon made $73 million , $46 million and $49 million of equity contributions to Pepco, DPL and ACE, respectively, in the second quarter of 2016 to fund the after-tax amounts of the customer bill credit and the customer base rate credit commitments. In addition, Exelon is committed to develop or to assist in the commercial development of approximately 37 MWs of new generation in Maryland, District of Columbia, and Delaware, 27 MWs of which are expected to be completed by 2018. These investments are expected to total approximately $137 million , are expected to be primarily capital in nature, and will generate future earnings at Exelon and Generation. The actual cost of investment in new generation may differ depending on the result of final negotiations and application of the most favored nation provision. Investment costs will be recognized as incurred and recorded on Exelon's and Generation's financial statements. Exelon has also committed to purchase 100 MWs of wind energy in PJM, to procure 120 MWs of wind RECs for the purpose of meeting Delaware's renewable portfolio standards, and to maintain and promote energy efficiency and demand response programs in the PHI jurisdictions. Pursuant to the various jurisdictions' merger approval conditions, over specified periods Pepco, DPL and ACE are not permitted to reduce employment levels due to involuntary attrition associated with the merger integration process and have made other commitments regarding hiring and relocation of positions. Exelon was previously named in suits filed in the Delaware Chancery Court alleging that individual directors of PHI breached their fiduciary duties by entering into the merger transaction, and that Exelon aided and abetted the individual directors’ breaches. The suits sought rescission of the merger and unspecified damages and costs. On June 1, 2016, the parties executed a settlement to resolve all claims, subject to the approval of the Delaware Court. A hearing had been scheduled for September 8, 2016 in the Delaware Court to consider whether to approve the settlement. However, on August 19, 2016, the plaintiffs advised Exelon that they had determined to dismiss the case in its entirety and with prejudice. On August 24, 2016, the Delaware Court issued an order approving the dismissal. In July 2015, the OPC, Public Citizen, Inc., the Sierra Club and the Chesapeake Climate Action Network (CCAN) filed motions to stay the MDPSC order approving the merger and in July and August, Exelon, PHI, the MDPSC, Prince George’s County and Montgomery County filed responses opposing the motions to stay. The judge issued an order denying the motions for stay on August 12, 2015. On January 8, 2016, the Circuit Court judge affirmed the MDPSC’s order approving the merger and denied the petitions for judicial review filed by the OPC, the Sierra Club, CCAN and Public Citizen, Inc. On January 19, 2016, the OPC filed a notice of appeal to the Maryland Court of Special Appeals, and on January 21, the Sierra Club and CCAN filed a notice of appeal. Exelon believes the matters are without merit. These appeals are not expected to be resolved any earlier than the first quarter of 2017. Between March 25, 2016 and April 22, 2016, various parties filed motions with the DCPSC to reconsider its March 23, 2016 order approving the merger. On June 17, 2016, the DCPSC denied all motions. In August 2016, the District of Columbia Office of People’s Counsel, the District of Columbia Government, and Public Citizen jointly with DC Sun each filed petitions for judicial review of the DCPSC’s March 23, 2016 order with the District of Columbia Court of Appeals. On September 9, 2016, the Court consolidated the appeals. Although the Court has not yet issued a scheduling order, a decision on this matter is not expected until the second or third quarter of 2017. Exelon believes the matters are without merit. Accounting for the Merger Transaction The total purchase price consideration of approximately $7.1 billion for the PHI Merger consisted of cash paid to PHI shareholders, cash paid for PHI preferred securities and cash paid for PHI stock-based compensation equity awards as follows: (In millions of dollars, except per share data) Total Consideration Cash paid to PHI shareholders at $27.25 per share (254 million shares outstanding at March 23, 2016) $ 6,933 Cash paid for PHI preferred stock (a) 180 Cash paid for PHI stock-based compensation equity awards (b) 29 Total purchase price $ 7,142 _____________ (a) As of December 31, 2015 , the preferred stock was included in Other non-current assets on Exelon's Consolidated Balance Sheets. (b) PHI’s unvested time-based restricted stock units and performance-based restricted stock units issued prior to April 29, 2014 were immediately vested and paid in cash upon the close of the merger. PHI’s remaining unvested time-based restricted stock units as of the close of the merger were cancelled. There were no remaining unvested performance-based restricted stock units as of the close of the merger. PHI shareholders received $27.25 of cash in exchange for each share of PHI common stock outstanding as of the effective date of the merger. In connection with the Merger Agreement, Exelon entered into a Subscription Agreement under which it purchased $180 million of a new class of nonvoting, nonconvertible and nontransferable preferred securities of PHI prior to December 31, 2015. On March 23, 2016 , the preferred securities were cancelled for no consideration to Exelon, and accordingly, the $180 million cash consideration previously paid to acquire the preferred securities was treated as purchase price consideration. The valuations performed in the first quarter of 2016 to assess the fair value of certain assets acquired and liabilities assumed were considered preliminary as a result of the short time period between the closing of the merger and the end of the first quarter of 2016. Accounting guidance provides that the allocation of the purchase price may be modified up to one year from the date of the merger as more information is obtained about the fair value of assets acquired and liabilities assumed; however, Exelon expects to finalize these amounts by the end of 2016. During the second and third quarters, certain modifications were made to preliminary valuation amounts for acquired property, plant and equipment, unamortized energy contracts, current liabilities, long-term debt, deferred income taxes and pension and OPEB liability resulting in a $16 million net decrease to goodwill. The preliminary amounts recognized are subject to further revision to the extent that additional information is obtained about the facts and circumstances that existed as of the acquisition date. Any changes to the fair value assessments may affect the purchase price allocation and could potentially impact goodwill. Exelon applied push-down accounting to PHI, and accordingly, the PHI assets acquired and liabilities assumed were recorded at their estimated fair values on Exelon’s and PHI's Consolidated Balance Sheets as of March 23, 2016, as follows: Preliminary Purchase Price Allocation Current assets $ 1,441 Property, plant and equipment 11,088 Regulatory assets 5,015 Other assets 248 Goodwill 4,000 Total assets $ 21,792 Current liabilities $ 2,752 Unamortized energy contracts 1,515 Regulatory liabilities 297 Long-term debt, including current maturities 5,636 Deferred income taxes 3,442 Pension and OPEB liability 821 Other liabilities 187 Total liabilities $ 14,650 Total purchase price $ 7,142 On its successor financial statements, PHI has recorded, beginning March 24, 2016, Membership interest equity of $7.2 billion , which is greater than the total $7.1 billion purchase price, reflecting the impact of a $59 million deferred tax liability recorded only at Exelon Corporate to reflect unitary state income tax consequences of the merger. The excess of the purchase price over the estimated fair value of the assets acquired and the liabilities assumed totaled $4.0 billion , which was recognized as goodwill by PHI and Exelon at the acquisition date, reflecting the value associated with enhancing Exelon's regulated utility portfolio of businesses, including the ability to leverage experience and best practices across the utilities and the opportunities for synergies. For purposes of future required impairment assessments, the goodwill has been preliminarily assigned to PHI's reportable units Pepco, DPL and ACE in the amounts of $1.7 billion , $1.1 billion and $1.2 billion , respectively. None of this goodwill is expected to be tax deductible. Immediately following closing of the merger, $235 million of net assets included in the table above associated with PHI's unregulated business interests were distributed by PHI to Exelon. Exelon contributed $163 million of such net assets to Generation. The fair values of PHI's assets and liabilities were determined based on significant estimates and assumptions that are judgmental in nature, including projected future cash flows (including timing), discount rates reflecting risk inherent in the future cash flows, future market prices and impacts of utility rate regulation. There were also judgments made to determine the expected useful lives assigned to each class of assets acquired. Exelon’s and PHI’s carrying amount of goodwill for the nine months ended September 30, 2016 was as follows: PHI Exelon (a) Beginning balance, December 31, 2015 $ — $ 2,672 Goodwill from business combination 4,016 4,016 Measurement period adjustments (16 ) (16 ) Ending balance, September 30, 2016 $ 4,000 $ 6,672 _____________ (a) As of September 30, 2016 , there were no changes to the carrying amount of goodwill for ComEd, see Note 11 — Intangible Assets of the Exelon 2015 Form 10-K for further information. Through its wholly-owned rate regulated utility subsidiaries, most of PHI’s assets and liabilities are subject to cost-of-service rate regulation. Under such regulation, rates charged to customers are established by a regulator to provide for recovery of costs and a fair return on invested capital, or rate base, generally measured at historical cost. In applying the acquisition method of accounting, for regulated assets and liabilities included in rate base or otherwise earning a return (primarily property, plant and equipment and regulatory assets earning a return), no fair value adjustments were recorded as historical cost is viewed as a reasonable proxy for fair value. Fair value adjustments were applied to the historical cost bases of other assets and liabilities subject to rate regulation but not earning a return (including debt instruments and pension and OPEB obligations). In these instances, a corresponding offsetting regulatory asset or liability was also established, as the underlying utility asset and liability amounts are recoverable from or refundable to customers at historical cost (and not at fair value) through the rate setting process. Similar treatment was applied for fair value adjustments to record intangible assets and liabilities, such as for electricity and gas energy supply contracts as further described below. Regulatory assets and liabilities established to offset fair value adjustments are amortized in amounts and over time frames consistent with the realization or settlement of the fair value adjustments, with no impact on reported net income. See Note 5 - Regulatory Matters for additional information regarding the fair value of regulatory assets and liabilities established by Exelon and PHI. Fair value adjustments were recorded at Exelon and PHI for the difference between the contract price and the market price of electricity and gas energy supply contracts of PHI’s wholly-owned rate regulated utility subsidiaries. These adjustments are intangible assets and liabilities classified as unamortized energy contracts on Exelon’s and PHI’s Consolidated Balance Sheets as of September 30, 2016 . The difference between the contract price and the market price at the acquisition date of the Merger was recognized for each contract as either an intangible asset or liability. In total, Exelon and PHI recorded a net $1.5 billion liability reflecting out-of-the-money contracts. The valuation of the acquired intangible assets and liabilities was estimated by applying either the market approach or the income approach depending on the nature of the underlying contract. The market approach was utilized when prices and other relevant information generated by market transactions involving comparable transactions were available. Otherwise the income approach, which is based upon discounted projected future cash flows associated with the underlying contracts, was utilized. In certain instances, the valuations were based upon certain unobservable inputs, which are considered Level 3 inputs, pursuant to applicable accounting guidance. Key estimates and inputs include forecasted power prices and the discount rate. The unamortized energy contract fair value adjustment amounts and the corresponding offsetting regulatory asset and liability amounts are amortized through Purchase power and fuel expense or Operating revenues, as applicable, over the life of the applicable contract in relation to the present value of the underlying cash flows as of the merger date. As mentioned, under cost-of-service rate regulation, rates charged to customers are established by a regulator to provide for recovery of costs and a fair return on invested capital, or rate base, generally measured at historical cost. Historical cost information therefore is the most relevant presentation for the financial statements of PHI’s rate regulated utility subsidiary registrants, Pepco, DPL and ACE. As such, Exelon and PHI did not push-down the application of acquisition accounting to PHI's utility registrants, and therefore the financial statements of Pepco, DPL and ACE do not reflect the revaluation of any assets and liabilities. The current impact of PHI, including its unregulated businesses, on Exelon's Consolidated Statements of Operations and Comprehensive Income includes Operating revenues of $1.4 billion and Net income of $169 million during the three months ended September 30, 2016 , and Operating revenues of $2.7 billion and Net loss of $(92) million during the nine months ended September 30, 2016 . For the three and nine months ended September 30, 2016 and 2015 , the Registrants have recognized costs to achieve the PHI acquisition as follows: Three Months Ended September 30, Nine Months Ended September 30, Acquisition, Integration and Financing Costs (a) 2016 2015 2016 2015 Exelon (b) $ 20 $ 22 $ 123 $ 84 Generation 9 10 29 30 ComEd (c) — 3 (6 ) 9 PECO 1 1 3 4 BGE (c) 1 2 (3 ) 4 Pepco (c) 3 1 26 3 DPL (c) 2 — 18 2 ACE 2 — 17 1 Successor Predecessor Successor Predecessor Three Months Ended September 30, Three Months Ended September 30, March 24 to September 30, January 1 to March 23, Nine Months Ended September 30, Acquisition, Integration and Financing Costs (a) 2016 2015 2016 2016 2015 PHI (c) $ 7 $ 3 $ 63 $ 29 $ 16 ______________ (a) The costs incurred are classified primarily within Operating and maintenance expense in the Registrants’ respective Consolidated Statements of Operations and Comprehensive Income, with the exception of the financing costs, which are included within Interest expense. Costs do not include merger commitments discussed above. (b) Reflects costs (benefits) recorded at Exelon related to financing, including mark-to-market activity on forward-starting interest rate swaps. (c) For the nine months ended September 30, 2016 , includes the reversal of previously incurred acquisition, integration and financing costs of $8 million , $6 million , $10 million , $3 million and $13 million incurred at ComEd, BGE, Pepco, DPL and PHI, respectively, that have been deferred and recorded as a regulatory asset for anticipated recovery. See Note 5 — Regulatory Matters for more information. Pro-forma Impact of the Merger The following unaudited pro forma financial information reflects the consolidated results of operations of Exelon as if the merger with PHI had taken place on January 1, 2015 . The unaudited pro forma information was calculated after applying Exelon’s accounting policies and adjusting PHI’s results to reflect purchase accounting adjustments. The unaudited pro forma financial information has been presented for illustrative purposes only and is not necessarily indicative of results of operations that would have been achieved had the merger events taken place on the dates indicated, or the future consolidated results of operations of the combined company. Three Months Ended Nine Months Ended Year Ended December 31, 2016 (a) 2015 (b) 2016 (a) 2015 (b) 2015 (c) Total operating revenues $ 9,002 $ 8,545 $ 24,468 $ 26,129 $ 33,823 Net income attributable to common shareholders 501 746 1,346 2,169 2,618 Basic earnings per share $ 0.54 $ 0.81 $ 1.46 $ 2.36 $ 2.85 Diluted earnings per share 0.54 0.81 1.45 2.35 2.84 ______________ (a) The amounts above include adjustments for non-recurring costs directly related to the merger of $20 million and $660 million for the three and nine months ended September 30, 2016 , respectively, and intercompany revenue of $171 million for the nine months ended September 30, 2016 . (b) The amounts above include adjustments for non-recurring costs directly related to the merger of $25 million and $100 million and intercompany revenue of $192 million and $426 million for the three and nine months ended September 30, 2015 , respectively. (c) The amounts above include adjustments for non-recurring costs directly related to the merger of $92 million and intercompany revenue of $559 million for the year ended December 31, 2015. Acquisition of ConEdison Solutions (Exelon and Generation) On September 1, 2016, Generation acquired the competitive retail electricity and natural gas business of Consolidated Edison Solutions, Inc. (ConEdison Solutions), a subsidiary of Consolidated Edison, Inc. for a purchase price of $257 million including net working capital of $204 million . The renewable energy, sustainable services and energy efficiency businesses of ConEdison Solutions are excluded from the transaction. As of September 30, 2016 , Generation had remitted $235 million to ConEdison Solutions and the remaining balance of $22 million , which is included in Other current liabilities on Exelon's and Generation's Consolidated Balance Sheets, will be paid during the first quarter of 2017. The following table summarizes the acquisition-date fair value of the consideration transferred and the assets and liabilities assumed for the ConEdison Solutions acquisition by Generation as of September 1, 2016: Total consideration transferred $ 257 Identifiable assets acquired and liabilities assumed Working capital assets $ 204 Property, plant and equipment 2 Mark-to-market derivative assets 6 Unamortized energy contract assets 100 Customer relationships 9 Other assets 1 Total assets $ 322 Mark-to-market derivative liabilities $ (65 ) Total liabilities $ (65 ) Total net identifiable assets, at fair value $ 257 The purchase price equaled the estimated fair value of the net assets acquired and the liabilities assumed and, therefore, no goodwill or bargain purchase was recorded as of September 30, 2016 . The purchase accounting is preliminary, and, although not expected, may be further adjusted from what is shown above. Accounting guidance provides that the allocation of the purchase price may be modified up to one year from the date of the acquisition as more information is obtained about the fair value of assets acquired and liabilities assumed; however, Generation expects to finalize these amounts by the first quarter of 2017. The fair values of ConEdison Solutions' assets and liabilities were determined based on significant estimates and assumptions that are judgmental in nature, including projected future cash flows (including timing), discount rates reflecting risk inherent in the future cash flows and future power and fuel market prices. It is impracticable to determine the post-close impact of ConEdison Solutions as the operations of ConEdison Solutions have been integrated into Generation's operations and are therefore not distinguishable after the acquisition. Proposed Acquisition of James A. FitzPatrick Nuclear Generating Station (Exelon and Generation) On August 8, 2016, Generation executed a series of agreements with Entergy Nuclear FitzPatrick LLC (Entergy) to acquire the 838MW single-unit James A. FitzPatrick (FitzPatrick) nuclear generating station located in Scriba, New York for a cash purchase price of $110 million . As part of the transaction, Generation would receive the FitzPatrick NDT fund assets and assume the obligation to decommission FitzPatrick. Closing of the transaction is currently anticipated to occur in the second quarter of 2017 and is dependent upon regulatory approval by FERC, NRC and the New York Public Service Commission (NYPSC). The transaction is also subject to the notification and reporting requirements of the HSR Act (which has been completed) and other customary closing conditions. The NRC license for FitzPatrick expires in 2034. Entergy had previously announced plans in November 2015 to early retire FitzPatrick at the end of the current fuel cycle in January 2017. Under the terms of the agreements, Generation will reimburse Entergy for approximately $200 million to $250 million of incremental costs to prepare for and conduct the plant refueling outage as well as to operate and maintain the plant after the refueling outage, scheduled to end in February 2017, through the closing date. These are costs which otherwise would have been avoided by FitzPatrick’s planned permanent shutdown in January 2017. Generation will be entitled to all revenues from FitzPatrick’s electricity and capacity sales for the period commencing upon completion of the refueling outage through the acquisition closing date. The agreements provide for certain termination rights, including the right of either party to terminate if the transaction has not been consummated within 12 months due to failure to obtain the required regulatory approvals. On October 11, 2016, Public Citizen, Inc. filed a protest with FERC challenging Generation and Entergy’s application to FERC for the transfer of ownership of FitzPatrick. No other party to the proceeding has filed any protests or comments. Generation and Entergy had requested FERC to approve the FitzPatrick transaction by November 18, 2016, however FERC is under no obligation to do so. The timing of FERC’s decision on Generation and Entergy’s application and the outcome of this protest are currently uncertain. Refer to Note 5 - Regulatory Matters for additional information on the New York CES and ZEC program. The transaction is expected to be accounted for as a business combination. For accounting and financial reporting purposes, the costs for which Generation reimburses Entergy as well as the revenue received from FitzPatrick prior to the closing of the transaction will be treated as part of the purchase price consideration. Generation will record the fair value of the assets acquired and liabilities assumed as of the acquisition date. To the extent the purchase price is greater than the fair value of the net assets acquired, goodwill will be recorded. To the extent the fair value of the net assets acquired is greater than the purchase price, a bargain purchase gain will be recorded. As of September 30, 2016 , Generation has paid a non-refundable deposit of $10 million and reimbursed Entergy for $9 million in costs all of which have been classified with Other noncurrent assets on Exelon's and Generation's Consolidated Balance Sheets. These amounts are also reflected within Acquisition of businesses on Exelon's and Generation's Consolidated Statements of Cash Flows. Asset Divestitures (Exelon, Generation, PHI and Pepco) On April 21, 2016, Generation completed the sale of the retired New Boston generating site, located in Boston, Massachusetts, resulting in a pre-tax gain of approximately $32 million . On May 2, 2016, Pepco completed the sale of the New York Avenue land parcel, located in Washington, D.C., resulting in a pre-tax gain of approximately $8 million at Pepco. Due to the fair value adjustments recorded at Exelon and PHI as part of purchase accounting, no gain was recorded in the Exelon and PHI Consolidated Statements of Operations and Comprehensive Income. On June 16, 2016, Generation initiated the sales process of its Upstream business by executing a forbearance agreement with the lenders of the nonrecourse debt. See Note 10 - Debt and Credit Agreements for more information. As of September 30, 2016 , $46 million of Property, plant and equipment and $5 million of Asset retirement obligation are classified as held for sale within Other current assets and Other current liabilities, respectively, on Exelon’s and Generation’s Consolidated Balance Sheets. In October 2016, Generation entered into an agreement to sell a portion of the Upstream assets which is expected to close before December 31, 2016. In July 2016, DPL completed the sale of a 9 acre land parcel located on South Madison Street in Wilmington, DE, resulting in a pre-tax gain of approximately $4 million . Due to the fair value adjustments recorded at Exelon and PHI as part of purchase accounting, no gain was recorded in the Exelon and PHI Consolidated Statements of Operations and Comprehensive Income.

Regulatory Matters (All Registr

Regulatory Matters (All Registrants)	9 Months Ended
	Sep. 30, 2016
Regulated Operations [Abstract]
Regulatory Matters (All Registrants)	5 . Regulatory Matters (All Registrants) Except for the matters noted below, the disclosures set forth in Note 3 - Regulatory Matters of the Exelon 2015 Form 10-K and Note 7 - Regulatory Matters of the PHI 2015 Form 10-K appropriately represent, in all material respects, the current status of regulatory and legislative proceedings of the Registrants. The following is an update to that discussion. Illinois Regulatory Matters Distribution Formula Rate (Exelon and ComEd). On April 13, 2016, ComEd filed its annual distribution formula rate with the ICC pursuant to EIMA. The filing establishes the revenue requirement used to set the rates that will take effect in January 2017 after the ICC’s review and approval, which is due by December 2016. The revenue requirement requested is based on 2015 actual costs plus projected 2016 capital additions as well as an annual reconciliation of the revenue requirement in effect in 2015 to the actual costs incurred that year. ComEd's 2016 filing request includes a total increase to the revenue requirement of $ 138 million , reflecting an increase of $ 139 million for the initial revenue requirement for 2017 and a decrease of $ 1 million related to the annual reconciliation for 2015. The revenue requirement for 2017 provides for a weighted average debt and equity return on distribution rate base of 6.71% inclusive of an allowed ROE of 8.64% , reflecting the average rate on 30 -year treasury notes plus 580 basis points. The annual reconciliation for 2015 provided for a weighted average debt and equity return on distribution rate base of 6.69% inclusive of an allowed ROE of 8.59% , reflecting the average rate on 30 -year treasury notes plus 580 basis points less a performance metrics penalty of 5 basis points. See table below for ComEd's regulatory assets associated with its distribution formula rate. For additional information on ComEd's distribution formula rate filings see Note 3 — Regulatory Matters of the Exelon 2015 Form 10-K. Grand Prairie Gateway Transmission Line (Exelon and ComEd). On December 2, 2013, ComEd filed a request to obtain the ICC’s approval to construct a 60-mile overhead 345kV transmission line that traverses Ogle, DeKalb, Kane and DuPage Counties in Northern Illinois. On October 22, 2014, the ICC issued an Order approving ComEd’s request. The City of Elgin and certain other parties each filed an appeal of the ICC Order in the Illinois Appellate Court for the Second District. ComEd then reached a settlement of the appeal filed by all parties except Elgin. On March 31, 2016, the Illinois Appellate Court issued its opinion affirming the ICC’s grant of a certificate to ComEd to construct and operate the line. Elgin did not seek further review of the Illinois Appellate Court decision. On May 28, 2014, in a separate proceeding, FERC issued an order granting ComEd’s request to include 100% of the capital costs recorded to construction work in progress during construction of the line in ComEd’s transmission rate base. If the project is cancelled or abandoned for reasons beyond ComEd’s control, FERC approved the ability for ComEd to recover 100% of its prudent costs incurred after May 21, 2014 and 50% of its costs incurred prior to May 21, 2014 in ComEd’s transmission rate base. The costs incurred for the project prior to May 21, 2014 were immaterial. ComEd has acquired the necessary land rights across the project route through voluntary transactions. ComEd began construction of the line during 2015 with an expected in-service date of 2017. FutureGen Industrial Alliance, Inc (Exelon and ComEd). During 2013, the ICC approved, and directed ComEd and Ameren (the Utilities) to enter into 20 -year sourcing agreements with FutureGen Industrial Alliance, Inc (FutureGen), under which FutureGen will retrofit and repower an existing plant in Morgan County, Illinois to a 166 MW near zero emissions coal-fueled generation plant, with an assumed commercial operation date in 2017. The order also directs ComEd and Ameren to recover these costs from their electric distribution customers through the use of a tariff, regardless of whether they purchase electricity from ComEd or Ameren, or from competitive electric generation suppliers. In February 2013, ComEd filed an appeal with the Illinois Appellate Court questioning the legality of requiring ComEd to procure power for retail customers purchasing electricity from competitive electric generation suppliers. On July 22, 2014, the Illinois Appellate Court issued its ruling re-affirming the ICC’s order requiring ComEd to enter into the sourcing agreement with FutureGen and allowing the use of a tariff to recover its costs. ComEd decided not to appeal the Illinois Appellate Court’s decision to the Illinois Supreme Court. However, the competitive electric generation suppliers and several large consumers petitioned for leave to appeal the Illinois Appellate Court’s decision. On November 26, 2014, the Illinois Supreme Court granted the petition. ComEd executed the sourcing agreement with FutureGen in accordance with the ICC’s order. In addition, ComEd filed a petition with the ICC seeking approval of the tariff allowing for the recovery of its costs associated with the FutureGen contract from all of its electric distribution customers, which was approved by the ICC on September 30, 2014. In February 2015, the DOE suspended funding for the cost development of FutureGen. On January 13, 2016, FutureGen informed the Illinois Supreme Court that it had ceased all development efforts on the FutureGen project. Accordingly, FutureGen requested that the court dismiss the proceeding as moot. In February 2016, FutureGen terminated its sourcing agreement with ComEd. On May 19, 2016, the Illinois Supreme Court dismissed the matter as moot. As a result, ComEd is under no further obligation under this agreement. Pennsylvania Regulatory Matters Pennsylvania Procurement Proceedings (Exelon and PECO). Through PECO’s first two PAPUC approved DSP Programs, PECO procured electric supply for its default electric customers through PAPUC approved competitive procurements. DSP I and DSP II expired on May 31, 2013 and May 31, 2015, respectively. The second DSP Program included a number of retail market enhancements recommended by the PAPUC in its previously issued Retail Markets Intermediate Work Plan Order. PECO was also directed to submit a plan to allow its low-income CAP customers to purchase their generation supply from EGSs beginning in April 2014. In May 2013, PECO filed its CAP Shopping Plan with the PAPUC. By an Order entered on January 24, 2014, the PAPUC approved PECO’s plan, with modifications, to make CAP shopping available beginning April 15, 2014. On March 20, 2014, the Office of Consumer Advocate (OCA) and low-income advocacy groups filed an appeal and emergency request for a stay with the Pennsylvania Commonwealth Court (Court), claiming that the PAPUC-ordered CAP Shopping plan does not contain sufficient protections for low-income customers. On July 14, 2015, the Court issued opinions on the OCA and low-income advocacy group appeal. Specifically, the Court remanded the issue to the PAPUC with instructions that it approve a rule revision to the PECO CAP Shopping Plan that would prohibit CAP customers from entering into contracts with an EGS that would impose early cancellation/termination fees. The PAPUC, as well as the low-income advocates and the Office of Consumer Advocate, appealed the Court's decision. On April 5, 2016, the Pennsylvania Supreme Court declined to accept the appeals. On May 11, 2016, the PAPUC issued a Secretarial Letter requiring PECO to propose a rule revision to the PECO CAP Shopping Plan consistent with the Court’s decision. On July 19, 2016, PECO filed a letter stating its intent to revise its Plan by September 1, 2016 to incorporate the rule revision. On September 1, 2016, PECO filed its proposed rule revision that is consistent with the Court’s opinion with a proposed effective date of April 14, 2017. On December 4, 2014, the PAPUC approved PECO's third DSP Program. The program has a 24-month term from June 1, 2015 through May 31, 2017, and complies with electric generation procurement guidelines set forth in Act 129. Under the program, PECO procured electric supply through four competitive procurements for fixed price full requirements contracts of two years or less for the residential classes and small and medium commercial classes and spot market price full requirement contracts for the large commercial and industrial class load. Beginning in June 2016, the medium commercial class (101-500 kW) moved to spot market pricing. In September 2016, PECO entered into contracts with PAPUC-approved bidders, including Generation, resulting from the final of its four scheduled procurements. Charges incurred for electric supply procured through contracts with Generation are included in purchased power from affiliates on PECO's Consolidated Statement of Operations and Comprehensive Income. On March 17, 2016, PECO filed its fourth DSP Program with the PAPUC proposing a 24-month term from June 1, 2017 through May 31, 2019, in compliance with electric generation procurement guidelines set forth in Act 129. On October 4, 2016, the Administrative Law Judge recommended that PECO’s previously filed partial settlement be approved without modification. The settlement would extend the program period through May 2021 and consolidate the Medium Commercial and Large Commercial classes of default service customers into a Consolidated Large Commercial Class proposed by the Company. The issue of PECO’s implementation of CAP Shopping was reserved for briefing, and the Administrative Law Judge determined that issue was not a part of the DSP IV case. A decision by the PAPUC is expected in December 2016. For further information on the Pennsylvania procurement proceedings, see Note 3 - Regulatory Matters of the Exelon 2015 Form 10-K. Energy Efficiency Programs (Exelon and PECO). On June 19, 2015, the PAPUC issued its Phase III EE&C implementation order that provides energy consumption reduction requirements for the third phase of Act 129’s EE&C program with a five-year term from June 1, 2016 through May 31, 2021. Pursuant to the Phase III implementation order, PECO filed its five-year EE&C Phase III Plan with the PAPUC on November 30, 2015. The Plan sets forth how PECO will reduce electric consumption by at least 1,962,659 MWh, with a goal of 2,100,875 MWh in its service territory for the period June 1, 2016 through May 31, 2021. The PAPUC approved PECO’s EE&C Phase III Plan, with requested clarifications, on May 19, 2016. For further information on energy efficiency programs, see Note 3 - Regulatory Matters of the Exelon 2015 Form 10-K. Maryland Regulatory Matters 2016 Maryland Electric Distribution Rate Case (Exelon, PHI and Pepco). On April 19, 2016, Pepco filed an application with the MDPSC requesting an increase of $127 million to its electric distribution base rates, which was later updated to $103 million , based on a requested ROE of 10.6% . The application is inclusive of a request seeking recovery of Pepco’s regulatory assets associated with its AMI program over a five-year period supported by evidence demonstrating that the benefits of the AMI program exceed the costs on a present value basis. Any adjustments to rates approved by the MDPSC are expected to take effect in November 2016. In addition to the proposed rate increase, Pepco is proposing to continue its Grid Resiliency Program initially approved in July 2013 in connection with Pepco’s electric distribution rate case filed in November 2012. Under the Grid Resiliency Program, Pepco is authorized to receive recovery of specific investments as the assets are placed in service through the Grid Resiliency Charge. In connection with the Grid Resiliency Program, Pepco proposes to accelerate improvement to priority feeders and install single-phase reclosing fuse technology by investing $16 million a year for two years for a total of $32 million . Pepco cannot predict how much of the requested rate increase the MDPSC will approve or if it will approve a continuation of Pepco’s Grid Resiliency Program proposal. 2016 Maryland Electric Distribution Base Rates (Exelon, PHI and DPL). On July 20, 2016, DPL filed an application with the MDPSC requesting an increase of $66 million to its electric distribution base rates, which was later updated to $57 million , based on a requested ROE of 10.6% . The application is inclusive of a request seeking recovery of DPL’s regulatory assets associated with its AMI program over a five-year period supported by evidence demonstrating that the benefits of the AMI program exceed the costs on a present value basis. Any adjustments to rates approved by the MDPSC are expected to take effect in February 2017. DPL cannot predict how much of the requested increase the MDPSC will approve. In addition to the proposed rate increase, DPL is proposing to continue its Grid Resiliency Program initially approved in September 2013 in connection with DPL’s electric distribution rate case filed in February 2013. Under the Grid Resiliency Program, DPL is authorized to receive recovery of specific investments as the assets are placed in service through the Grid Resiliency Charge. In connection with the Grid Resiliency Program, DPL proposes to accelerate improvement to priority feeders and install single-phase reclosing fuse technology by investing $4.6 million a year for two years for a total of $9.2 million . DPL cannot predict whether the MDPSC will approve a continuation of DPL’s Grid Resiliency Program proposal. 2015 Maryland Electric and Natural Gas Distribution Rate Case (Exelon and BGE). On November 6, 2015, and as amended through the course of the proceeding, BGE filed for electric and natural gas base rate increases with the MDPSC, ultimately requesting annual increases of $116 million and $78 million respectively, of which $104 million and $37 million , were related to recovery of electric and natural gas smart grid initiative costs, respectively. BGE also proposed to recover an annual increase of approximately $30 million for Baltimore City underground conduit fees through a surcharge. On June 3, 2016, the MDPSC issued an order in which the MDPSC found compelling evidence to conclude that BGE’s smart grid initiative overall was cost beneficial to customers. However, the June 3 order contained several cost disallowances and adjustments, including not allowing BGE to defer or recover through a surcharge the $30 million increase in annual Baltimore City underground conduit fees. On June 30, 2016, BGE filed a petition for rehearing of the June 3 order requesting that the MDPSC modify its order to reverse certain decisions including the decision associated with the Baltimore City underground conduit fees. OPC also subsequently filed for a petition for rehearing of the June 3 order. On July 29, 2016, the MDPSC issued an order on the petitions for rehearing that reversed certain of its prior cost disallowances and adjustments related to the smart grid initiative. Through the combination of the orders, the MDPSC authorized electric and natural gas rate increases of $44 million and $48 million , respectively, and an allowed ROE for the electric and natural gas distribution businesses of 9.75% and 9.65% , respectively. The new electric and natural gas base rates took effect for service rendered on or after June 4, 2016. However, MDPSC’s July 29 order on the petition on rehearing still did not allow BGE to defer or recover through a surcharge the increase in Baltimore City underground conduit fees. On August 26, 2016, BGE filed an appeal of the MDPSC's orders with the Circuit Court for Baltimore County. On August 29, 2016, the residential consumer advocate also filed an appeal of the MDPSC's order but with the Circuit Court for Baltimore City. BGE cannot predict the outcomes of these appeals. Refer to the Smart Meter and Smart Grid Investment disclosure below for further details on the impact of the ultimate disallowances contained in the orders to BGE. Smart Meter and Smart Grid Investments (Exelon and BGE). In August 2010, the MDPSC approved a comprehensive smart grid initiative for BGE that included the planned installation of 2 million residential and commercial electric and natural gas smart meters at an expected total cost of $480 million of which $200 million was funded by SGIG. The MDPSC’s approval ordered BGE to defer the associated incremental costs, depreciation and amortization, and an appropriate return, in a regulatory asset until such time as a cost-effective advanced metering system is implemented. As of September 30, 2016 and December 31, 2015 , the balance of BGE's regulatory asset was $235 million and $196 million , respectively, representing incremental program deployment costs. The current quarter balance of $235 million consists of three major components, including $148 million of unamortized incremental deployment costs of the AMI program, $55 million of unamortized costs of the non-AMI meters replaced under the program, and $32 million related to post-test year incremental program deployment costs incurred prior to approval became effective June 2016. The balance as of September 30, 2016 reflects the impact of the cost disallowances and adjustments discussed below. The incremental deployment costs for the AMI program and the non-AMI meter components of the regulatory asset are being recovered through rates and amortized to expense over a 10 year period, while the post-test year incremental program deployment costs have not yet been approved for recovery by the MDPSC. A return on the regulatory asset is currently included in rates, except for the $55 million portion representing the unamortized cost of the retired non-AMI meters and a $32 million portion related to post-test year incremental program deployment costs. As part of the 2015 electric and natural gas distribution rate case filed on November 6, 2015, BGE sought recovery of its smart grid initiative costs, supported by evidence demonstrating that BGE had, in fact, implemented a cost-beneficial advanced metering system. On June 3, 2016, the MDPSC issued an order concluding that the smart grid initiative overall is cost beneficial to its customers. However, the June 3 order contained several cost disallowances and adjustments including disallowances of certain program and meter installation costs and denial of recovery of any return on unrecovered costs for non-AMI meters replaced under the program. On June 30, 2016, BGE filed a petition for rehearing of the June 3 order requesting that the MDPSC modify its order to reverse certain decisions and change certain of the cost disallowances and adjustments to enable BGE to defer those costs for recovery through future electric and natural gas rates. OPC also subsequently filed for a petition for rehearing of the June 3 order. On July 29, 2016, the MDPSC issued an order on the petitions for rehearing that reversed certain of its prior cost disallowances and adjustments related to the smart grid initiative. On August 26, 2016, BGE filed an appeal of the MDPSC's orders with the Circuit Court for Baltimore County. On August 29, 2016, the residential consumer advocate also filed an appeal of the MDPSC's order but with the Circuit Court for Baltimore City. BGE cannot predict the outcomes of these appeals. As a combined result of the MDPSC orders, BGE recorded a $ 52 million charge to Operating and maintenance expense in Exelon’s and BGE’s Consolidated Statements of Operations and Comprehensive Income reducing certain regulatory assets and other long-lived assets. Pursuant to the combined MDPSC orders, BGE also reclassified $55 million of non-AMI plant costs from Property, plant and equipment, net to Regulatory assets on Exelon's and BGE's Consolidated Balance Sheets as of September 30, 2016 . For further information, see Note 3 - Regulatory Matters of the Exelon 2015 Form 10-K. 2013 Maryland Electric and Natural Gas Distribution Rate Case (Exelon and BGE). On May 17, 2013, and as amended on August 23, 2013, BGE filed for electric and natural gas base increases with the MDPSC. In addition to these requested rate increases, BGE’s application also included a request for recovery of incremental capital expenditures and operating costs associated with BGE’s proposed short-term reliability improvement plan (the ERI initiative) in response to a MDPSC order through a surcharge separate from base rates. On December 13, 2013, the MDPSC issued an order authorizing BGE to recover through a surcharge mechanism costs associated with five ERI initiative programs designed to accelerate electric reliability improvements premised upon the condition that the MDPSC approve specific projects in advance of cost recovery. As of September 30, 2016 , BGE has received approval of its updated surcharge filings three times for rates to be effective in 2014, 2015 and 2016. In January 2014, the residential consumer advocate in Maryland filed an appeal to the order issued by the MDPSC on December 13, 2013 in BGE's 2013 electric and natural gas distribution rate cases. The residential consumer advocate filed its related legal memorandum on August 22, 2014, challenging the MDPSC's approval of the ERI initiative surcharge. BGE submitted a response to the appeal on October 15, 2014, and a hearing was held on November 17, 2014. On October 26, 2015, the Circuit Court for Baltimore City issued an order affirming the MDPSC decision. However, on November 23, 2015, the residential consumer advocate filed an appeal of the Circuit Court's decision with the Maryland Court of Special Appeals. On March 7, 2016, the consumer advocate withdrew its appeal and no further action is expected. MDPSC New Generation Contract Requirement (Exelon, Generation, BGE, PHI, Pepco and DPL). On April 12, 2012, the MDPSC issued an order that requires BGE, Pepco and DPL (collectively, the Contract EDCs) to negotiate and enter into a contract with the winning bidder of a competitive bidding process to build one new power plant in the range of 650 to 700 MWs beginning in 2015, in amounts proportional to their relative SOS loads. Under the terms of the order, the winning bidder was to construct a 661 MW natural gas-fired combined cycle generation plant in Waldorf, Maryland, with an expected commercial operation date of June 1, 2015, and each of the Contract EDCs was to recover its costs associated with the contract through surcharges on its respective SOS customers. In response to a complaint filed by a group of generating companies in the PJM region, on September 30, 2013, the U.S. District Court for the District of Maryland issued a ruling that the MDPSC’s April 2012 order violated the Supremacy Clause of the U.S. Constitution by attempting to regulate wholesale prices. In contrast, on October 1, 2013, in response to appeals filed by the Contract EDCs and other parties, the Maryland Circuit Court for Baltimore City upheld the MDPSC’s orders requiring the Contract EDCs to enter into the contracts. On October 24, 2013, the Federal district court issued an order ruling that the contracts are illegal and unenforceable. In November 2013 both the winning bidder and the MDPSC appealed the Federal district court decision to the U.S. Court of Appeals for the Fourth Circuit, which affirmed the lower Federal court ruling. On November 26, 2014, both the winning bidder and the MDPSC petitioned the U.S. Supreme Court to consider hearing an appeal of the Fourth Circuit decision. On October 19, 2015, the U.S. Supreme Court agreed to review the decision. On April 19, 2016, the U.S. Supreme Court unanimously affirmed the Fourth Circuit's ruling upholding the Federal district court's decision. The decision of the Maryland Circuit Court was appealed to the Maryland Court of Special Appeals and was stayed pending decision by the U.S. Supreme Court. On August 1, 2016, the Contract EDCs submitted a filing requesting that the MDPSC take notice of the U.S. Supreme Court’s decision, and notifying the MDPSC that the Contract EDCs will dismiss their appeal pending at the Maryland Court of Special Appeals. On September 14, 2016, the Maryland Court of Special Appeals dismissed the pending appeal and the matter is considered closed. Delaware Regulatory Matters 2016 Electric and Natural Gas Distribution Base Rates (Exelon, PHI and DPL). On May 17, 2016, DPL filed an application with the DPSC to increase its annual electric and natural gas distribution base rates by $63 million and $22 million , respectively, based on a requested ROE of 10.6% . While the DPSC is not required to issue a decision on the application within a specified period of time, Delaware law allowed DPL to put into effect $2.5 million of the rate increase two months after filing the applications which were effective July 16, 2016. It also allows the entire requested rate increase seven months after filing, subject to a cap and a refund obligation based on the final DPSC order. DPL cannot predict how much of the requested increase the DPSC will approve. District of Columbia Regulatory Matters 2016 Electric Distribution Base Rates (Exelon, PHI and Pepco). On June 30, 2016, Pepco filed an application with the DCPSC to increase its annual electric distribution base rates by $86 million , which was updated to $82 million on October 14, 2016, based on a requested ROE of 10.6% . The DCPSC has issued a procedural schedule indicating a final decision will be issued by July 25, 2017. Any adjustments to its rates approved by the DCPSC are expected to take effect soon thereafter. Pepco cannot predict how much of the requested increase the DCPSC will approve. On April 18, 2016, a party to a separate DCPSC proceeding filed a motion to suspend Pepco’s bill stabilization adjustment (BSA), which decouples distribution revenues from utility customers from the amount of electricity delivered. On September 9, 2016, the DCPSC denied the party’s motion and determined that the appropriate forum in which to determine whether the BSA continues to be just and reasonable is in Pepco’s rate case proceeding. In addition, the DCPSC stated that it was putting Pepco on notice that all funds collected for the BSA from January 2015 to the issuance of a decision in the rate case proceeding are subject to refund should the DCPSC determine that such funds were not justly or reasonably collected. On October 7, 2016, Pepco filed for reconsideration of this order and requested clarification that the order was not final and that the BSA matter would be decided in the base rate case. Pepco also argued that, if the order were considered final, the DCPSC reconsider its ruling that funds collected from the BSA can be retroactively refunded. Pepco cannot predict the outcome of this matter or the impact of a refund if ordered by the DCPSC. District of Columbia Power Line Undergrounding Initiative (Exelon, PHI and Pepco). In May 2014, the Council of the District of Columbia enacted the Electric Company Infrastructure Improvement Financing Act of 2014 (the Improvement Financing Act), which provided enabling legislation for the District of Columbia Power Line Undergrounding (DC PLUG) initiative which would selectively place underground some of the District of Columbia’s most outage-prone power lines. The Improvement Financing Act provides that: (i) Pepco is to fund approximately $500 million of the estimated cost to complete the DC PLUG initiative, recovering those costs through a volumetric surcharge on the electric bills of Pepco District of Columbia customers; (ii) $375 million of the DC PLUG initiative cost is to be financed by the District of Columbia’s issuance of securitized bonds, which bonds will be repaid through a volumetric surcharge (the DDOT surcharge) on the electric bills of Pepco District of Columbia customers that Pepco will remit to the District of Columbia; and (iii) the remaining costs up to $125 million are to be covered by the existing capital projects program of the District of Columbia Department of Transportation (DDOT). Pepco will not earn a return on or a return of the cost of the assets funded with the proceeds of the securitized bonds or assets that are constructed by DDOT under its capital projects program, but ownership and responsibility for the operation and maintenance of such assets will be transferred to Pepco for a nominal amount. In June 2014, Pepco and DDOT filed a Triennial Plan related to the construction of selected underground feeders in the District of Columbia. In August 2014, Pepco filed an application for the issuance of a financing order to provide for the issuance of the District's bonds. In March 2016, the DCPSC's orders approving the Triennial Plan and the application for financing were upheld upon the resolution of appeals that had been filed with the District of Columbia Court of Appeals. In compliance with the Improvement Financing Act, on September 30, 2016, Pepco and DDOT filed a Second Triennial Plan. Recognizing the delays to the First Triennial Plan, Pepco and DDOT requested that the DCPSC hold the Second Triennial Plan in abeyance. In June 2015, an agency of the federal government served by Pepco asserted that the DDOT surcharge constitutes a tax on end users from which the federal government is immune. PHI is currently evaluating the assertion and the resolution of this matter will likely further delay implementation of the DC PLUG initiative. New Jersey Regulatory Matters 2016 Electric Distribution Base Rates (Exelon, PHI and ACE). On August 24, 2016, the NJBPU issued an order approving a stipulation of settlement among ACE, the New Jersey Division of Rate Counsel, NJBPU Staff and Unimin Corporation, and an increase of $45 million (before New Jersey sales and use tax) to its electric distribution base rates, with the new rates effective immediately. The stipulation of settlement provided that a determination on PowerAhead would be separated into a phase II of the rate proceeding and decided at a later date and the parties would seek to resolve the matter by the end of 2016, although resolution will most likely occur in the first quarter of 2017. PowerAhead includes capital investments to advance modernization of the electric grid through energy efficiency, increased distributed generation, and resiliency, focused on improving the distribution system's ability to withstand major storm events. ACE cannot predict if the NJBPU will approve the PowerAhead initiative. Update and Reconciliation of Certain Under-Recovered Balances (Exelon, PHI and ACE). O n February 1, 2016, ACE submitted its 2016 annual petition with the NJBPU seeking to reconcile and update (i) charges related to the recovery of above-market costs associated with ACE’s long-term power purchase contracts with the NUGs and (ii) costs related to surcharges for the New Jersey Societal Benefit Program (a statewide public interest program that is intended to benefit low income customers and address other public policy goals) and ACE’s uncollectible accounts. The net impact of adjusting the charges as proposed is an overall annual rate increase of $9 million (revised to $19 million in April 2016, based upon an update for actuals through March 2016), including New Jersey sales and use tax. The matter is pending at the NJBPU. New York Regulatory Matters New York Clean Energy Standard (Exelon, Generation). On August 1, 2016, the New York Public Service Commission (NYPSC) issued an order establishing the Clean Energy Standard (CES), a component of which includes creation of a Tier 3 Zero Emission Credit (ZEC) program targeted at preserving the environmental attributes of zero-emissions nuclear-powered generating facilities that meet the criteria demonstrating public necessity as determined by the NYPSC. The New York State Energy Research and Development Authority (NYSERDA) will centrally procure the ZECs from eligible plants through a 12-year contract, to be administered in six two-year tranches, extending from April 1, 2017 through March 31, 2029. ZEC payments will be made to the eligible resources based upon the number of MWh produced, subject to specified caps and minimum performance requirements. The price to be paid for the ZECs under each tranche will be administratively determined using a formula based on the social cost of carbon as determined by the federal government. The ZEC price for the first tranche has been set at $17.48 per MWh of production. Following the first tranche, the price will be updated bi-annually. Each Load Serving Entity (LSE) s

Impairment of Long-lived Assets

Impairment of Long-lived Assets (Exelon and Generation)	9 Months Ended
	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Impairment of Long-Lived Assets (Exelon and Generation)	6 . Impairment of Long-Lived Assets (Exelon and Generation) Long-Lived Assets (Exelon and Generation) During the first quarter of 2016 , significant changes in Generation’s intended use of the Upstream oil and gas assets, developments with nonrecourse debt held by its upstream subsidiary CEU Holdings, LLC (as described in Note 10 - Debt and Credit Agreements ) and continued declines in both production volumes and commodity prices suggested that the carrying value may be impaired. Generation concluded that the estimated undiscounted future cash flows and fair value of its Upstream properties were less than their carrying values. As a result, a pre-tax impairment charge of $119 million was recorded in March 2016 within Operating and maintenance expense in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income. On June 16, 2016, Generation initiated the sales process of its Upstream business by executing a forbearance agreement with the lenders of the nonrecourse debt, see Note 10 — Debt and Credit Agreements for additional information. As a result, the Upstream assets and liabilities are classified as held for sale on Exelon's and Generation's Consolidated Balance Sheets at September 30, 2016 . See Note 4 — Mergers, Acquisitions and Dispositions for additional information. An additional pre-tax impairment charge of $15 million was recorded in September 2016 within Operating and maintenance expense in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income due to further declines in fair value. Further declines in commodity prices or further developments with Generation’s intended use or disposition of the assets could potentially result in future impairments of the Upstream assets. Generation evaluates long-lived assets for recoverability whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. In the second quarter of 2016, updates to the Company's long-term view of energy and capacity prices suggested that the carrying value of a group of merchant wind assets, located in West Texas, may be impaired. Upon review, the estimated undiscounted future cash flows and fair value of the group were less than their carrying value. The fair value analysis was based on the income approach using significant unobservable inputs (Level 3) including revenue and generation forecasts, projected capital and maintenance expenditures and discount rates. As a result of the fair value analysis, long-lived merchant wind assets held and used with a carrying amount of approximately $60 million were written down to their fair value of $24 million and a pre-tax impairment charge of $36 million was recorded during the second quarter in Operating and maintenance expense in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income. Also in the second quarter of 2016, updates to the Company's long-term view, as described above, in conjunction with the retirement announcements of the Quad Cities and Clinton nuclear plants in Illinois suggested that the carrying value of our Midwest asset group may be impaired. Generation completed a comprehensive review of the estimated undiscounted future cash flows of the Midwest asset group and no impairment charge was required. Like-Kind Exchange Transaction (Exelon) In June 2000, UII, LLC (formerly Unicom Investments, Inc.) (UII), a wholly owned subsidiary of Exelon Corporation, entered into transactions pursuant to which UII invested in coal-fired generating station leases (Headleases) with the Municipal Electric Authority of Georgia (MEAG). The generating stations were leased back to MEAG as part of the transactions (Leases). On March 31, 2016, UII and MEAG finalized an agreement to terminate the MEAG Headleases, the MEAG Leases, and other related agreements prior to their expiration dates. As a result of the lease termination, UII received an early termination payment of $360 million from MEAG and wrote-off the $356 million net investment in the MEAG Headleases and the Leases. The transaction resulted in a pre-tax gain of $4 million which is reflected in Operating and maintenance expense in Exelon's Consolidated Statements of Operations and Comprehensive Income. See Note 11 — Income Taxes for additional information.

Early Nuclear Plant Retirements

Early Nuclear Plant Retirements Early Nuclear Plant Retirements (Exelon, Generation)	9 Months Ended
	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Implications Of Potential Early Retirement Disclosure [Text Block]	7 . Early Nuclear Plant Retirements (Exelon and Generation) Exelon and Generation continue to evaluate the current and expected economic value of each of Generation’s nuclear plants. Factors that will continue to affect the economic value of Generation’s nuclear plants include, but are not limited to: market power prices, results of capacity auctions, potential legislative and regulatory solutions to ensure nuclear plants are fairly compensated for their carbon-free emissions, and the impact of final rules from the EPA requiring reduction of carbon and other emissions and the efforts of states to implement those final rules. In 2015, Generation identified the Quad Cities, Clinton and Ginna nuclear plants as having the greatest risk of early retirement based on economic valuation and other factors. At that time, Exelon and Generation deferred retirement decisions on Clinton and Quad Cities until 2016 in order to participate in the 2016-2017 MISO primary reliability auction and the 2019-2020 PJM capacity auctions held in April and May 2016, respectively, as well as to provide Illinois policy makers with additional time to consider needed reforms and for MISO to consider market design changes to ensure long-term power system reliability in southern Illinois. In April 2016, Clinton cleared the MISO primary reliability auction as a price taker for the 2016-2017 planning year. The resulting capacity price is insufficient to cover cash operating costs and a risk-adjusted rate of return to shareholders. In May 2016, Quad Cities did not clear in the PJM capacity auction for the 2019-2020 planning year and will not receive capacity revenue for that period. Based on these capacity auction results, and given the lack of progress on Illinois energy legislation and MISO market reforms, on June 2, 2016 Generation announced it will move forward to shut down the Clinton and Quad Cities nuclear plants on June 1, 2017 and June 1, 2018, respectively. The current Nuclear Regulatory Commission (NRC) licenses for Clinton and Quad Cities expire in 2026 and 2032, respectively. Generation is proceeding with the market and regulatory notifications that must be made to shut down the plants, including notification to the NRC on June 20, 2016, and filing of a deactivation notice with PJM for Quad Cities on July 6, 2016. Generation will formally notify MISO of its plans to close Clinton later this year. In 2016, as a result of the plant retirement decision for Clinton and Quad Cities, Exelon and Generation recognized one-time charges in Operating and maintenance expense of $146 million related to materials and supplies inventory reserve adjustments, employee-related costs and construction work-in-progress (CWIP) impairments, among other items. In addition to these one-time charges, there will be ongoing annual incremental non-cash charges to earnings stemming from shortening the expected economic useful life of Clinton and Quad Cities primarily related to accelerated depreciation of plant assets (including any asset retirement costs (ARC)), accelerated amortization of nuclear fuel, and additional asset retirement obligation (ARO) accretion expense associated with the changes in decommissioning timing and cost assumptions. Through September 30, 2016, Exelon's and Generation's results include an incremental $443 million of pre-tax expense for these items as summarized in the table below. Please refer to Note 12 — Nuclear Decommissioning for additional detail on changes to the Nuclear decommissioning ARO balances resulting from the early retirement of Clinton and Quad Cities. Income statement expense (pre-tax) September 30, 2016 Depreciation and Amortization Accelerated depreciation (a) $ 459 Accelerated nuclear fuel amortization 37 Operating and Maintenance Increase ARO accretion, net of contractual offset (b) 2 Contractual offset for ARC depreciation (b) (55 ) Total $ 443 _________ (a) Reflects incremental accelerated depreciation of plant assets, including any ARC. (b) For Quad Cities based on the regulatory agreement with the Illinois Commerce Commission, decommissioning-related activities are offset within Exelon's and Generation's Consolidated Statements of Operations and Comprehensive Income. The offset results in an equal adjustment to the noncurrent payables to ComEd at Generation and an adjustment to the regulatory liabilities at ComEd. Likewise, ComEd has recorded an equal noncurrent affiliate receivable from Generation and corresponding regulatory liability. The Three Mile Island (TMI) nuclear plant also did not clear in the May 2016 PJM capacity auction for the 2019-2020 planning year and will not receive capacity revenue for that period. This is the second consecutive year that TMI failed to clear the capacity auction. Although the plant is committed to operate through May 2019, the plant faces continued economic challenges and Exelon and Generation are exploring all options to return it to profitability. While a portion of the Byron nuclear plant’s capacity did not clear the PJM 2019-2020 planning year capacity auction, the plant is committed to run through May 2020. The company’s other nuclear plants in PJM cleared in the auction, except Oyster Creek, which did not participate in the auction given Exelon's and Generation’s previous commitment to cease operation of the Oyster Creek nuclear plant by the end of 2019. In New York, the Ginna and Nine Mile Point nuclear plants continue to face significant economic challenges and risk of retirement before the end of each unit’s respective operating license period (2029 for Ginna and Nine Mile Point Unit 1, and 2046 for Nine Mile Point Unit 2). On August 1, 2016, NYPSC issued an order adopting the Clean Energy Standard (CES), which would provide payments to Ginna and Nine Mile Point for the environmental attributes of their production. Subject to Ginna and Nine Mile Point entering into a satisfactory contract with the NYSERDA, as required under the CES, and subject to prevailing over any administrative or legal challenges, the CES will allow Ginna and Nine Mile Point to continue to operate at least through the life of the program (March 31, 2029). The approved RSSA currently requires Ginna to continue operating through the RSSA term expiring in March 2017. If Ginna does not plan to retire shortly after the expiration of the RSSA, notification to that effect was required to be filed with the NYPSC no later than September 30, 2016. On September 30, 2016, Ginna filed the required notice with the NYPSC of its intent to continue operating beyond the March 31, 2017 expiry of the RSSA, conditioned upon successful execution of an agreement between Ginna and NYSERDA for the sale of ZECs under the CES. Negotiations with NYSERDA are ongoing and contract execution is currently targeted for completion in the fourth quarter of 2016. Refer to Note 5 - Regulatory Matters for additional discussion on the Ginna RSSA and the New York CES. The following table provides the balance sheet amounts as of September 30, 2016 for significant assets and liabilities associated with the three nuclear plants currently considered by management to be at the greatest risk of early retirement due to current economic valuations and other factors. (in millions) TMI Ginna NMP Asset Balances Materials and supplies inventory $ 39 $ 31 $ 70 Nuclear fuel inventory, net 93 41 214 Completed plant, net 956 124 1,151 Construction work in progress 38 13 53 Liability Balances Asset retirement obligation (492 ) (667 ) (780 ) NRC License Renewal Term 2034 2029 2029 (unit 1) 2046 (unit 2) Assuming the successful implementation of the CES and its continued effectiveness, Generation and CENG would no longer consider Ginna and Nine Mile Point to be at heightened risk of early retirement; however, absent the CES for the full expected duration they will remain at heightened risk. The precise timing of an early retirement date for any of these plants, and the resulting financial statement impacts, may be affected by a number of factors, including the status of potential regulatory or legislative solutions, results of any transmission system reliability study assessments, the nature of any co-owner requirements and stipulations, and decommissioning trust fund requirements, among other factors. However, the earliest retirement date for any plant would usually be the first year in which the unit does not have capacity obligations, where applicable, and just prior to its next scheduled nuclear refueling outage.

Fair Value of Financial Assets

Fair Value of Financial Assets and Liabilities (All Registrants)	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets and Liabilities (All Registrants)	8 . Fair Value of Financial Assets and Liabilities (All Registrants) Fair Value of Financial Liabilities Recorded at the Carrying Amount The following tables present the carrying amounts and fair values of the Registrants’ short-term liabilities, long-term debt, SNF obligation, trust preferred securities (long-term debt to financing trusts or junior subordinated debentures) and preferred stock as of September 30, 2016 and December 31, 2015 : Exelon September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 567 $ — $ 567 $ — $ 567 Long-term debt (including amounts due within one year) (a) 34,842 1,075 34,272 2,279 37,626 Long-term debt to financing trusts (b) 642 — — 692 692 SNF obligation 1,023 — 856 — 856 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 536 $ 3 $ 533 $ — $ 536 Long-term debt (including amounts due within one year) (a) 25,145 931 23,644 1,349 25,924 Long-term debt to financing trusts (b) 641 — — 673 673 SNF obligation 1,021 — 818 — 818 Generation September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 40 $ — $ 40 $ — $ 40 Long-term debt (including amounts due within one year) (a) 9,255 — 8,015 1,684 9,699 SNF obligation 1,023 — 856 — 856 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 29 $ — $ 29 $ — $ 29 Long-term debt (including amounts due within one year) (a) 8,959 — 7,767 1,349 9,116 SNF obligation 1,021 — 818 — 818 ComEd September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 10 $ — $ 10 $ — $ 10 Long-term debt (including amounts due within one year) (a) 7,031 — 8,081 — 8,081 Long-term debt to financing trusts (b) 205 — — 218 218 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 294 $ — $ 294 $ — $ 294 Long-term debt (including amounts due within one year) (a) 6,509 — 7,069 — 7,069 Long-term debt to financing trusts (b) 205 — — 213 213 PECO September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 2,879 $ — $ 3,266 $ — $ 3,266 Long-term debt to financing trusts 184 — — 207 207 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 2,580 $ — $ 2,786 $ — $ 2,786 Long-term debt to financing trusts 184 — — 195 195 BGE September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 2,662 $ — $ 2,966 $ — $ 2,966 Long-term debt to financing trusts (b) 252 — — 267 267 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 213 $ 3 $ 210 $ — $ 213 Long-term debt (including amounts due within one year) (a) 1,858 — 2,044 — 2,044 Long-term debt to financing trusts (b) 252 — — 264 264 PHI September 30, 2016 Carrying Amount Fair Value Successor Level 1 Level 2 Level 3 Total Short-term liabilities $ 517 $ — $ 517 $ — $ 517 Long-term debt (including amounts due within one year) 6,044 — 5,698 594 6,292 December 31, 2015 Carrying Amount Fair Value Predecessor Level 1 Level 2 Level 3 Total Short-term liabilities $ 958 $ — $ 958 $ — $ 958 Long-term debt (including amounts due within one year) (a) 5,279 — 5,231 586 5,817 Preferred stock 183 — — 183 183 Pepco September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 2,350 $ — $ 3,000 $ 2 $ 3,002 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 64 $ — $ 64 $ — $ 64 Long-term debt (including amounts due within one year) (a) 2,351 — 2,673 — 2,673 DPL September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 17 $ — $ 17 $ — $ 17 Long-term debt (including amounts due within one year) (a) 1,265 — 1,277 101 1,378 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 105 $ — $ 105 $ — $ 105 Long-term debt (including amounts due within one year) (a) 1,265 — 1,185 103 1,288 ACE September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 1,167 $ — $ 1,058 $ 299 $ 1,357 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 5 $ — $ 5 $ — $ 5 Long-term debt (including amounts due within one year) (a) 1,201 — 1,044 280 1,324 ________ (a) Includes unamortized debt issuance costs which are not fair valued of $204 million , $68 million , $47 million , $16 million , $15 million , $30 million , $10 million , and $6 million for Exelon, Generation, ComEd, PECO, BGE, Pepco, DPL and ACE, respectively, as of September 30, 2016 . Includes unamortized debt issuance costs of $180 million , $70 million , $38 million , $15 million , $9 million , $49 million , $31 million , $10 million , and $6 million for Exelon, Generation, ComEd, PECO, BGE, PHI, Pepco, DPL and ACE, respectively, as of December 31, 2015 . (b) Includes unamortized debt issuance costs which are not fair valued of $7 million , $1 million , and $6 million for Exelon, ComEd and BGE, respectively, as of September 30, 2016 and December 31, 2015 . Short-Term Liabilities. The short-term liabilities included in the tables above are comprised of dividends payable (included in other current liabilities) (Level 1) and short-term borrowings (Level 2). The Registrants’ carrying amounts of the short-term liabilities are representative of fair value because of the short-term nature of these instruments. Long-Term Debt. The fair value amounts of Exelon’s taxable debt securities (Level 2) and private placement taxable debt securities (Level 3) are determined by a valuation model that is based on a conventional discounted cash flow methodology and utilizes assumptions of current market pricing curves. In order to incorporate the credit risk of the Registrants into the discount rates, Exelon obtains pricing (i.e., U.S. Treasury rate plus credit spread) based on trades of existing Exelon debt securities as well as debt securities of other issuers in the electric utility sector with similar credit ratings in both the primary and secondary market, across the Registrants’ debt maturity spectrum. The credit spreads of various tenors obtained from this information are added to the appropriate benchmark U.S. Treasury rates in order to determine the current market yields for the various tenors. The yields are then converted into discount rates of various tenors that are used for discounting the respective cash flows of the same tenor for each bond or note. Due to low trading volume of private placement debt, qualitative factors such as market conditions, low volume of investors and investor demand, this debt is classified as Level 3. The fair value of Exelon's equity units (Level 1) are valued based on publicly traded securities issued by Exelon. The fair value of Generation’s and PHI's non-government-backed fixed rate nonrecourse debt (Level 3) is based on market and quoted prices for its own and other nonrecourse debt with similar risk profiles. Given the low trading volume in the nonrecourse debt market, the price quotes used to determine fair value will reflect certain qualitative factors, such as market conditions, investor demand, new developments that might significantly impact the project cash flows or off-taker credit, and other circumstances related to the project (e.g., political and regulatory environment). The fair value of Generation’s government-backed fixed rate project financing debt (Level 3) is largely based on a discounted cash flow methodology that is similar to the taxable debt securities methodology described above. Due to the lack of market trading data on similar debt, the discount rates are derived based on the original loan interest rate spread to the applicable Treasury rate as well as a current market curve derived from government-backed securities. Variable rate project financing debt resets on a monthly or quarterly basis and the carrying value approximates fair value (Level 2). When trading data is available on variable rate project financing debt, the fair value is based on market and quoted prices for its own and other nonrecourse debt with similar risk profiles (Level 2). Generation, Pepco, DPL and ACE also have tax-exempt debt (Level 2). Due to low trading volume in this market, qualitative factors, such as market conditions, investor demand, and circumstances related to the issuer (e.g., conduit issuer political and regulatory environment), may be incorporated into the credit spreads that are used to obtain the fair value as described above. Variable rate tax-exempt debt (Level 2) resets on a regular basis and the carrying value approximates fair value. SNF Obligation . The carrying amount of Generation’s SNF obligation (Level 2) is derived from a contract with the DOE to provide for disposal of SNF from Generation’s nuclear generating stations. When determining the fair value of the obligation, the future carrying amount of the SNF obligation estimated to be settled in 2025 is calculated by compounding the current book value of the SNF obligation at the 13-week Treasury rate. The compounded obligation amount is discounted back to present value using Generation’s discount rate, which is calculated using the same methodology as described above for the taxable debt securities, and an estimated maturity date of 2025. Long-Term Debt to Financing Trusts . Exelon’s long-term debt to financing trusts is valued based on publicly traded securities issued by the financing trusts. Due to low trading volume of these securities, qualitative factors, such as market conditions, investor demand, and circumstances related to each issue, this debt is classified as Level 3. Preferred Stock . The fair value of these securities is determined based on the carrying value of the shares per the Subscription Agreement between PHI and Exelon. See Note 16 - Mezzanine Equity for further details. Recurring Fair Value Measurements Exelon records the fair value of assets and liabilities in accordance with the hierarchy established by the authoritative guidance for fair value measurements. The hierarchy prioritizes the inputs to valuation techniques used to measure fair value into three levels as follows: • Level 1 — quoted prices (unadjusted) in active markets for identical assets or liabilities that the Registrants have the ability to liquidate as of the reporting date. • Level 2 — inputs other than quoted prices included within Level 1 that are directly observable for the asset or liability or indirectly observable through corroboration with observable market data. • Level 3 — unobservable inputs, such as internally developed pricing models or third-party valuations for the asset or liability due to little or no market activity for the asset or liability. Transfers in and out of levels are recognized as of the end of the reporting period when the transfer occurred. Given derivatives categorized within Level 1 are valued using exchange-based quoted prices within observable periods, transfers between Level 2 and Level 1 were not material. Additionally, there were no significant transfers between Level 1 and Level 2 during the nine months ended September 30, 2016 for cash equivalents, nuclear decommissioning trust fund investments, pledged assets for Zion Station decommissioning, Rabbi trust investments, and deferred compensation obligations. For derivative contracts, transfers into Level 2 from Level 3 generally occur when the contract tenor becomes more observable and due to changes in market liquidity or assumptions for certain commodity contracts. Generation and Exelon In accordance with the applicable guidance on fair value measurement, certain investments that are measured at fair value using the NAV per share as a practical expedient are no longer classified within the fair value hierarchy and are included under "Not subject to leveling" in the table below. See Note 2 - New Accounting Pronouncements for additional information. The following tables present assets and liabilities measured and recorded at fair value on Exelon's and Generation’s Consolidated Balance Sheets on a recurring basis and their level within the fair value hierarchy as of September 30, 2016 and December 31, 2015 : Generation Exelon As of September 30, 2016 Level 1 Level 2 Level 3 Not subject to leveling Total Level 1 Level 2 Level 3 Not subject to leveling Total Assets Cash equivalents (a) $ 94 $ — $ — $ — $ 94 $ 1,645 $ — $ — $ — $ 1,645 NDT fund investments Cash equivalents (b) 163 20 — — 183 163 20 — — 183 Equities 3,566 335 — 1,992 5,893 3,566 335 — 1,992 5,893 Fixed income Corporate debt — 1,629 257 — 1,886 — 1,629 257 — 1,886 U.S. Treasury and agencies 1,363 33 — — 1,396 1,363 33 — — 1,396 Foreign governments — 50 — — 50 — 50 — — 50 State and municipal debt — 268 — — 268 — 268 — — 268 Other (c) — 56 — 510 566 — 56 — 510 566 Fixed income subtotal 1,363 2,036 257 510 4,166 1,363 2,036 257 510 4,166 Middle market lending — — 436 23 459 — — 436 23 459 Private equity — — — 138 138 — — — 138 138 Real estate — — — 306 306 — — — 306 306 NDT fund investments subtotal (d) 5,092 2,391 693 2,969 11,145 5,092 2,391 693 2,969 11,145 Pledged assets for Zion Station decommissioning Cash equivalents 14 — — — 14 14 — — — 14 Equities — 1 — — 1 — 1 — — 1 Fixed income U.S. Treasury and agencies 28 2 — — 30 28 2 — — 30 Corporate debt — 3 — — 3 — 3 — — 3 Generation Exelon As of September 30, 2016 Level 1 Level 2 Level 3 Not subject to leveling Total Level 1 Level 2 Level 3 Not subject to leveling Total Fixed income subtotal 28 5 — — 33 28 5 — — 33 Middle market lending — — 19 68 87 — — 19 68 87 Pledged assets for Zion Station (e) 42 6 19 68 135 42 6 19 68 135 Rabbi trust investments Cash equivalents 10 — — — 10 83 — — — 83 Mutual funds 19 — — — 19 50 — — — 50 Fixed income — — — — — — 14 — — 14 Life insurance contracts — 18 — — 18 — 64 21 — 85 Rabbi trust investments subtotal 29 18 — — 47 133 78 21 — 232 Commodity derivative assets Economic hedges 883 2,790 1,948 — 5,621 884 2,790 1,948 — 5,622 Proprietary trading 11 51 36 — 98 11 51 36 — 98 Effect of netting and allocation of collateral (f) (927 ) (2,527 ) (896 ) — (4,350 ) (928 ) (2,527 ) (896 ) — (4,351 ) Commodity derivative assets subtotal (33 ) 314 1,088 — 1,369 (33 ) 314 1,088 — 1,369 Interest rate and foreign currency derivative assets Derivatives designated as hedging instruments — — — — — — 39 — — 39 Economic hedges — 28 — — 28 — 28 — — 28 Proprietary trading 7 1 — — 8 7 1 — — 8 Effect of netting and allocation of collateral (4 ) (17 ) — — (21 ) (4 ) (17 ) — — (21 ) Interest rate and foreign currency derivative assets subtotal 3 12 — — 15 3 51 — — 54 Other investments — — 42 — 42 — — 42 — 42 Total assets 5,227 2,741 1,842 3,037 12,847 6,882 2,840 1,863 3,037 14,622 Liabilities Commodity derivative liabilities Economic hedges (1,037 ) (2,917 ) (1,160 ) — (5,114 ) (1,037 ) (2,917 ) (1,404 ) — (5,358 ) Proprietary trading (10 ) (53 ) (39 ) — (102 ) (10 ) (53 ) (39 ) — (102 ) Effect of netting and allocation of collateral (f) 1,012 2,777 1,046 — 4,835 1,012 2,777 1,046 — 4,835 Commodity derivative liabilities subtotal (35 ) (193 ) (153 ) — (381 ) (35 ) (193 ) (397 ) — (625 ) Interest rate and foreign currency derivative liabilities Derivatives designated as hedging instruments — (18 ) — — (18 ) — (18 ) — — (18 ) Economic hedges — (19 ) — — (19 ) — (19 ) — — (19 ) Proprietary trading (6 ) — — — (6 ) (6 ) — — — (6 ) Effect of netting and allocation of collateral 8 16 — — 24 8 16 — — 24 Interest rate and foreign currency derivative liabilities subtotal 2 (21 ) — — (19 ) 2 (21 ) — — (19 ) Deferred compensation obligation — (32 ) — — (32 ) — (131 ) — — (131 ) Total liabilities (33 ) (246 ) (153 ) — (432 ) (33 ) (345 ) (397 ) — (775 ) Total net assets $ 5,194 $ 2,495 $ 1,689 $ 3,037 $ 12,415 $ 6,849 $ 2,495 $ 1,466 $ 3,037 $ 13,847 Generation Exelon As of December 31, 2015 Level 1 Level 2 Level 3 Not subject to leveling Total Level 1 Level 2 Level 3 Not subject to leveling Total Assets Cash equivalents (a) $ 104 $ — $ — $ — $ 104 $ 5,766 $ — $ — $ — $ 5,766 NDT fund investments Cash equivalents (b) 219 92 — — 311 219 92 — — 311 Equities 3,008 — — 1,894 4,902 3,008 — — 1,894 4,902 Fixed income Corporate debt — 1,824 242 — 2,066 — 1,824 242 — 2,066 U.S. Treasury and agencies 1,323 15 — — 1,338 1,323 15 — — 1,338 Foreign governments — 61 — — 61 — 61 — — 61 State and municipal debt — 326 — — 326 — 326 — — 326 Other (c) — 147 — 390 537 — 147 — 390 537 Fixed income subtotal 1,323 2,373 242 390 4,328 1,323 2,373 242 390 4,328 Middle market lending — — 428 — 428 — — 428 — 428 Private equity — — — 125 125 — — — 125 125 Real estate — — — 35 35 — — — 35 35 Other — — — 216 216 — — — 216 216 NDT fund investments subtotal (d) 4,550 2,465 670 2,660 10,345 4,550 2,465 670 2,660 10,345 Pledged assets for Zion Station decommissioning Cash equivalents — 17 — — 17 — 17 — — 17 Equities 1 5 — — 6 1 5 — — 6 Fixed income U.S. Treasury and agencies 6 2 — — 8 6 2 — — 8 Corporate debt — 46 — — 46 — 46 — — 46 Other — 1 — — 1 — 1 — — 1 Fixed income subtotal 6 49 — — 55 6 49 — — 55 Middle market lending — — 22 105 127 — — 22 105 127 Pledged assets for Zion Station decommissioning subtotal (e) 7 71 22 105 205 7 71 22 105 205 Rabbi trust investments Mutual funds 17 — — — 17 48 — — — 48 Life insurance contracts — 13 — — 13 — 36 — — 36 Rabbi trust investments subtotal 17 13 — — 30 48 36 — — 84 Commodity derivative assets Economic hedges 1,922 3,467 1,707 — 7,096 1,922 3,467 1,707 — 7,096 Proprietary trading 36 64 30 — 130 36 64 30 — 130 Effect of netting and allocation of collateral (f) (1,964 ) (2,629 ) (564 ) — (5,157 ) (1,964 ) (2,629 ) (564 ) — (5,157 ) Commodity derivative assets subtotal (6 ) 902 1,173 — 2,069 (6 ) 902 1,173 — 2,069 Interest rate and foreign currency derivative assets Derivatives designated as hedging instruments — — — — — — 25 — — 25 Economic hedges — 20 — — 20 — 20 — — 20 Proprietary trading 10 5 — — 15 10 5 — — 15 Effect of netting and allocation of collateral (3 ) (3 ) — — (6 ) (3 ) (3 ) — — (6 ) Generation Exelon As of December 31, 2015 Level 1 Level 2 Level 3 Not subject to leveling Total Level 1 Level 2 Level 3 Not subject to leveling Total Interest rate and foreign currency derivative assets subtotal 7 22 — — 29 7 47 — — 54 Other investments — — 33 — 33 — — 33 — 33 Total assets 4,679 3,473 1,898 2,765 12,815 10,372 3,521 1,898 2,765 18,556 Liabilities Commodity derivative liabilities Economic hedges (2,382 ) (3,348 ) (850 ) — (6,580 ) (2,382 ) (3,348 ) (1,097 ) — (6,827 ) Proprietary trading (33 ) (57 ) (37 ) — (127 ) (33 ) (57 ) (37 ) — (127 ) Effect of netting and allocation of collateral (f) 2,440 3,186 765 — 6,391 2,440 3,186 765 — 6,391 Commodity derivative liabilities subtotal 25 (219 ) (122 ) — (316 ) 25 (219 ) (369 ) — (563 ) Interest rate and foreign currency derivative liabilities Derivatives designated as hedging instruments — (16 ) — — (16 ) — (16 ) — — (16 ) Economic hedges — (3 ) — — (3 ) — (3 ) — — (3 ) Proprietary trading (12 ) — — — (12 ) (12 ) — — — (12 ) Effect of netting and allocation of collateral 12 3 — — 15 12 3 — — 15 Interest rate and foreign currency derivative liabilities subtotal — (16 ) — — (16 ) — (16 ) — — (16 ) Deferred compensation obligation — (30 ) — — (30 ) — (99 ) — — (99 ) Total liabilities 25 (265 ) (122 ) — (362 ) 25 (334 ) (369 ) — (678 ) Total net assets $ 4,704 $ 3,208 $ 1,776 $ 2,765 $ 12,453 $ 10,397 $ 3,187 $ 1,529 $ 2,765 $ 17,878 ________ (a) Generation excludes cash of $282 million and $329 million at September 30, 2016 and December 31, 2015 and restricted cash of $161 million and $121 million at September 30, 2016 and December 31, 2015 . Exelon excludes cash of $398 million and $763 million at September 30, 2016 and December 31, 2015 and restricted cash of $197 million and $178 million at September 30, 2016 and December 31, 2015 and includes long term restricted cash of $22 million at September 30, 2016 , which is reported in other deferred debits on the balance sheet. (b) Includes $64 million and $52 million of cash received from outstanding repurchase agreements at September 30, 2016 and December 31, 2015 , respectively, and is offset by an obligation to repay upon settlement of the agreement as discussed in (d) below. (c) Includes derivative instruments of $(10) million and $(8) million , which have a total notional amount of $1,073 million and $1,236 million at September 30, 2016 and December 31, 2015 , respectively. The notional principal amounts for these instruments provide one measure of the transaction volume outstanding as of the periods ended and do not represent the amount of the company's exposure to credit or market loss. (d) Excludes net liabilities of $(69) million and $(3) million at September 30, 2016 and December 31, 2015 , respectively. These items consist of receivables related to pending securities sales, interest and dividend receivables, repurchase agreement obligations, and payables related to pending securities purchases. The repurchase agreements are generally short-term in nature with durations generally of 30 days or less. (e) Excludes net assets of less than $1 million and $1 million at September 30, 2016 and December 31, 2015 , respectively. These items consist of receivables related to pending securities sales, interest and dividend receivables, and payables related to pending securities purchases. (f) Collateral posted to/(received) from counterparties totaled $85 million , $250 million and $150 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of September 30, 2016 . Collateral posted (received) from counterparties, net of collateral paid to counterparties, totaled $476 million , $557 million and $201 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of December 31, 2015 . ComEd, PECO and BGE The following tables present assets and liabilities measured and recorded at fair value on ComEd's, PECO's and BGE's Consolidated Balance Sheets on a recurring basis and their level within the fair value hierarchy as of September 30, 2016 and December 31, 2015 : ComEd PECO BGE As of September 30, 2016 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents (a) $ — $ — $ — $ — $ 521 $ — $ — $ 521 $ 375 $ — $ — $ 375 Rabbi trust investments Mutual funds — — — — 7 — — 7 4 — — 4 Life insurance contracts — — — — — 11 — 11 — — — — Rabbi trust investments subtotal — — — — 7 11 — 18 4 — — 4 Total assets — — — — 528 11 — 539 379 — — 379 Liabilities Deferred compensation obligation — (8 ) — (8 ) — (10 ) — (10 ) — (4 ) — (4 ) Mark-to-market derivative liabilities (b) — — (244 ) (244 ) — — — — — — — — Total liabilities — (8 ) (244 ) (252 ) — (10 ) — (10 ) — (4 ) — (4 ) Total net assets (liabilities) $ — $ (8 ) $ (244 ) $ (252 ) $ 528 $ 1 $ — $ 529 $ 379 $ (4 ) $ — $ 375 ComEd PECO BGE As of December 31, 2015 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents (a) $ 29 $ — $ — $ 29 $ 271 $ — $ — $ 271 $ 25 $ — $ — $ 25 Rabbi trust investments Mutual funds — — — — 8 — — 8 4 — — 4 Life insurance contracts — — — — — 12 — 12 — — — — Rabbi trust investments subtotal — — — — 8 12 — 20 4 — — 4 Total assets 29 — — 29 279 12 — 291 29 — — 29 Liabilities Deferred compensation obligation — (8 ) — (8 ) — (12 ) — (12 ) — (4 ) — (4 ) Mark-to-market derivative liabilities (b) — — (247 ) (247 ) — — — — — — — — Total liabilities — (8 ) (247 ) (255 ) — (12 ) — (12 ) — (4 ) — (4 ) Total net assets (liabilities) $ 29 $ (8 ) $ (247 ) $ (226 ) $ 279 $ — $ — $ 279 $ 29 $ (4 ) $ — $ 25 _________ (a) ComEd excludes cash of $44 million and $38 million at September 30, 2016 and December 31, 2015 and restricted cash of $2 million and $2 million at September 30, 2016 and December 31, 2015 . PECO excludes cash of $27 million and $27 million at September 30, 2016 and December 31, 2015 and $1 million of restricted cash at September 30, 2016 . BGE excludes cash of $13 million and $6 million at September 30, 2016 and December 31, 2015 and restricted cash of $2 million and $2 million at September 30, 2016 and December 31, 2015 and includes long term restricted cash of $3 million at September 30, 2016 , which is reported in other deferred debits on the balance sheet. (b) The Level 3 balance consists of the current and noncurrent liability of $19 million and $225 million , respectively, at September 30, 2016 , and $23 million and $224 million , respectively, at December 31, 2015 , related to floating-to-fixed energy swap contracts with unaffiliated suppliers. PHI, Pepco, DPL and ACE The following tables present assets and liabilities measured and recorded at fair value on PHI's, Pepco's, DPL's and ACE's Consolidated Balance Sheets on a recurring basis and their level within the fair value hierarchy as of September 30, 2016 and December 31, 2015 : Successor Predecessor As of September 30, 2016 As of December 31, 2015 PHI Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents (a) $ 347 $ — $ — $ 347 $ 42 $ — $ — $ 42 Mark-to-market derivative assets (b)(c) 1 — — 1 — — 18 18 Effect of netting and allocation of collateral (1 ) — — (1 ) — — — — Mark-to-market derivative assets subtotal — — — — — — 18 18 Rabbi trust investments Cash equivalents 73 — — 73 12 — — 12 Fixed income — 14 — 14 — 15 — 15 Life insurance contracts — 22 21 43 — 27 19 46 Rabbi trust investments subtotal 73 36 21 130 12 42 19 73 Total assets 420 36 21 477 54 42 37 133 Liabilities Deferred compensation obligation — (28 ) — (28 ) — (30 ) — (30 ) Mark-to-market derivative liabilities (b) — — — — (2 ) — — (2 ) Effect of netting and allocation of collateral — — — — 2 — — 2 Mark-to-market derivative liabilities subtotal — — — — — — — — Total liabilities — (28 ) — (28 ) — (30 ) — (30 ) Total net assets $ 420 $ 8 $ 21 $ 449 $ 54 $ 12 $ 37 $ 103 Pepco DPL ACE As of September 30, 2016 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents (a) $ 127 $ — $ — $ 127 $ — $ — $ — $ — $ 194 $ — $ — $ 194 Mark-to-market derivative assets (b) — — — — 1 — — 1 — — — — Effect of netting and allocation of collateral — — — — (1 ) — — (1 ) — — — — Mark-to-market derivative assets subtotal — — — — — — — — — — — — Rabbi trust investments Cash equivalents 43 — — 43 — — — — — — — — Fixed income — 14 — 14 — — — — — — — — Life insurance contracts — 22 21 43 — — — — — — — — Rabbi trust investments subtotal 43 36 21 100 — — — — — — — — Total assets 170 36 21 227 — — — — 194 — — 194 Liabilities Deferred compensation obligation — (5 ) — (5 ) — (1 ) — (1 ) — — — — Total liabilities — (5 ) — (5 ) — (1 ) — (1 ) — — — — Total net assets (liabilities) $ 170 $ 31 $ 21 $ 222 $ — $ (1 ) $ — $ (1 ) $ 194 $ — $ — $ 194 Pepco DPL ACE As of December 31, 2015 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents $ 2 $ — $ — $ 2 $ — $ — $ — $ — $ 30 $ — $ — $ 30 Rabbi trust investments Cash equivalents 11 — — 11 — — — — — — — — Fixed income — 15 — 15 — — — — — — — — Life insurance contracts — 23 19 42 — — — — — — — — Rabbi trust investments subtotal 11 38 19 68 — — — — — — — — Total assets 13 38 19 70 — — — — 30 — — 30 Liabilities Deferred compensation obligation — (6 ) — (6 ) — (1 ) — (1 ) — — — — Mark-to-market derivative liabilities (b) — — — — (2 ) — — (2 ) — — — — Effect of netting and allocation of collateral — — — — 2 — — 2 — — — — Mark-to-market derivative liabilities subtotal — — — — — — — — — — — — Total liabilities — (6 ) — (6 ) — (1 ) — (1 ) — — — — Total net assets (liabilities) $ 13 $ 32 $ 19 $ 64 $ — $ (1 ) $ — $ (1 ) $ 30 $ — $ — $ 30 _______ (a) PHI excludes cash of $20 million and $16 million at September 30, 2016 and December 31, 2015 and includes long term restricted cash of $19 million and $18 million at September 30, 2016 and December 31, 2015 which is reported in other deferred debits on the balance sheet. Pepco excludes cash of $8 million and $5 million at September 30, 2016 and December 31, 2015 . DPL excludes cash of $4 million and $5 million at September 30, 2016 and December 31, 2015 . ACE excludes cash of $5 million and $3 million at September 30, 2016 and December 31, 2015 and includes long term restricted cash of $19 million and $18 million at September 30, 2016 and December 31, 2015 which is reported in other deferred debits on the balance sheet. (b) Represents natural gas futures purchased by DPL as part of a natural gas hedging program approved by the DPSC. (c) Prior to the PHI Merger, PHI recorded derivative assets for the embedded call and redemption features on the shares of Preferred Stock outstanding as of December 31, 2015. See Note 16 - Mezzanine Equity for additional information. As a result of the PHI Merger, the PHI preferred stock derivative was reduced to zero as of March 23, 2016 . The following tables present the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis during the three and nine months ended September 30, 2016 and 2015 : Successor Generation ComEd PHI Exelon Three Months Ended September 30, 2016 NDT Fund Investments Pledged Assets for Zion Station Decommissioning Mark-to-Market Derivatives Other Investments Total Generation Mark-to-Market Derivatives (a) Life Insurance Contracts Eliminated in Consolidation Total Balance as of June 30, 2016 $ 715 $ 25 $ 609 $ 37 $ 1,386 $ (221 ) $ 20 $ — $ 1,185 Total realized / unrealized gains (losses) Included in net income (4 ) — 95 (b) 1 92 — 1 — 93 Included in noncurrent payables to affiliates 6 — — — 6 — — (6 ) — Included in payable for Zion Station decommissioning — (1 ) — — (1 ) — — — (1 ) Included in regulatory assets — — — — — (23 ) — 6 (17 ) Change in collateral — — 31 — 31 — — — 31 Purchases, sales, issuances and settlements Purchases 4 — 207 (d) 3 214 — — — 214 Sales — (5 ) (2 ) — (7 ) — — — (7 ) Issuances — — — — — — — — — Settlements (28 ) — — — (28 ) — — — (28 ) Transfers into Level 3 — — (1 ) 1 — — — — — Transfers out of Level 3 — — (4 ) — (4 ) — — — (4 ) Balance at September 30, 2016 $ 693 $ 19 $ 935 $ 42 $ 1,689 $ (244 ) $ 21 $ — $ 1,466 The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of September 30, 2016 $ 3 $ — $ 285 $ — $ 288 $ — $ — $ — $ 288 Successor Generation ComEd PHI (c) Exelon Nine Months Ended September 30, 2016 NDT Fund Investments Pledged Assets for Zion Station Decommissioning Mark-to-Market Derivatives Other Investments Total Generation Mark-to-Market Derivatives (a) Life Insurance Contracts Eliminated in Consolidation Total Balance as of December 31, 2015 $ 670 $ 22 $ 1,051 $ 33 $ 1,776 $ (247 ) $ — $ — $ 1,529 Included due to merger — — — — — — — 20 — 20 Total realized / unrealized gains (losses) Included in net income 2 — (339 ) (b) 1 (336 ) — 2 — (334 ) Included in noncurrent payables to affiliates 18 — — — 18 — — (18 ) — Included in payable for Zion Station decommissioning — 1 — — 1 — — — 1 Included in regulatory assets/liabilities — — — — — 3 — 18 21 Change in collateral — — (51 ) — (51 ) — — — (51 ) Purchases, sales, issuances and settlements Purchases 123 1 289 (d) 7 420 — — — 420 Sales (1 ) (5 ) (5 ) — (11 ) — — — (11 ) Issuances — — — — — — (1 ) — (1 ) Settlements (119 ) — — — (119 ) — — — (119 ) Transfers into Level 3 — — 1 1 2 — — — 2 Transfers out of Level 3 — — (11 ) — (11 ) — — — (11 ) Balance as of September 30, 2016 $ 693 $ 19 $ 935 $ 42 $ 1,689 $ (244 ) $ 21 $ — $ 1,466 The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of September 30, 2016 $ 7 $ — $ 240 $ — $ 247 $ — $ 1 $ — $ 248 ___________________ (a) Includes $25 million of decreases in fair value and realized losses due to settlements of $2 million recorded in purchased power expense associated with floating-to-fixed energy swap contracts with unaffiliated suppliers for the three months ended September 30, 2016 . Includes $ 10 million of decreases in fair value and realized losses due to settlements of $ 13 million for the nine months ended September 30, 2016 . (b) Includes a reduction for the reclassification of $190 million and $579 million

Derivative Financial Instrument

Derivative Financial Instruments (All Registrants)	9 Months Ended
	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments (All Registrants)	9 . Derivative Financial Instruments (All Registrants) The Registrants use derivative instruments to manage commodity price risk, foreign currency exchange risk and interest rate risk related to ongoing business operations. Commodity Price Risk (All Registrants) To the extent the amount of energy Generation produces differs from the amount of energy it has contracted to sell, Exelon and Generation are exposed to market fluctuations in the prices of electricity, fossil fuels and other commodities. Each of the Registrants employ established policies and procedures to manage their risks associated with market fluctuations in commodity prices by entering into physical and financial derivative contracts, including swaps, futures, forwards, options and short-term and long-term commitments to purchase and sell energy and energy-related products. The Registrants believe these instruments, which are classified as either economic hedges or non-derivatives, mitigate exposure to fluctuations in commodity prices. Derivative accounting guidance requires that derivative instruments be recognized as either assets or liabilities at fair value, with changes in fair value of the derivative recognized in earnings each period. Other accounting treatments are available through special election and designation, provided they meet specific, restrictive criteria both at the time of designation and on an ongoing basis. These alternative permissible accounting treatments include normal purchase normal sale (NPNS), cash flow hedge and fair value hedge. For Generation, all derivative economic hedges related to commodities are recorded at fair value through earnings for the combined company, referred to as economic hedges in the following tables. The Registrants have applied the NPNS scope exception to certain derivative contracts for the forward sale of generation, power procurement agreements and natural gas supply agreements. Generation has also entered into bilateral long-term contractual obligations for sales of energy to load-serving entities, including electric utilities, municipalities, electric cooperatives and retail load aggregators, as well as contractual obligations to deliver energy to market participants who primarily focus on the resale of energy products for delivery. These non-derivative contracts are accounted for primarily under the accrual method of accounting. Additionally, Generation is exposed to certain market risks through its proprietary trading activities. The proprietary trading activities are a complement to Generation’s energy marketing portfolio but represent a small portion of Generation’s overall energy marketing activities. Economic Hedging. The Registrants are exposed to commodity price risk primarily relating to changes in the market price of electricity, fossil fuels and other commodities associated with price movements resulting from changes in supply and demand, fuel costs, market liquidity, weather conditions, governmental regulatory and environmental policies and other factors. Within Exelon, Generation has the most exposure to commodity price risk. As such, Generation uses a variety of derivative and non-derivative instruments to manage the commodity price risk of its electric generation facilities, including power and gas sales, fuel and energy purchases, natural gas transportation and pipeline capacity agreements and other energy-related products marketed and purchased. In order to manage these risks, Generation may enter into fixed-price derivative or non-derivative contracts to hedge the variability in future cash flows from forecasted sales of energy and gas and purchases of fuel and energy. The objectives for entering into such hedges include fixing the price for a portion of anticipated future electricity sales at a level that provides an acceptable return on electric generation operations, fixing the price of a portion of anticipated fuel purchases for the operation of power plants, and fixing the price for a portion of anticipated energy purchases to supply load-serving customers. The portion of forecasted transactions hedged may vary based upon management’s policies and hedging objectives, the market, weather conditions, operational and other factors. Generation is also exposed to differences between the locational settlement prices of certain economic hedges and the hedged generating units. This price difference is actively managed through other instruments which include derivative congestion products, whose changes in fair value are recognized in earnings each period, and auction revenue rights, which are accounted for on an accrual basis. In general, increases and decreases in forward market prices have a positive and negative impact, respectively, on Generation’s owned and contracted generation positions that have not been hedged. Generation hedges commodity price risk on a ratable basis over three-year periods. As of September 30, 2016 , the proportion of expected generation hedged for the major reportable segments is 98% - 101% , 85% - 88% and 54% - 57% for 2016 , 2017 and 2018 , respectively. The percentage of expected generation hedged is the amount of equivalent sales divided by the expected generation. Expected generation is the volume of energy that best represents our commodity position in energy markets from owned or contracted for capacity based upon a simulated dispatch model that makes assumptions regarding future market conditions, which are calibrated to market quotes for power, fuel, load following products, and options. Equivalent sales represent all hedging products, which include economic hedges and certain non-derivative contracts including Generation’s sales to the Utility Registrants to serve their retail load. On December 17, 2010, ComEd entered into several 20-year floating-to-fixed energy swap contracts with unaffiliated suppliers for the procurement of long-term renewable energy and associated RECs. Delivery under the contracts began in June 2012. These contracts are designed to lock in a portion of the long-term commodity price risk resulting from the renewable energy resource procurement requirements in the Illinois Settlement Legislation. ComEd has not elected hedge accounting for these derivative financial instruments. ComEd records the fair value of the swap contracts on its balance sheet. Because ComEd receives full cost recovery for energy procurement and related costs from retail customers, the change in fair value each period is recorded by ComEd as a regulatory asset or liability. See Note 3 — Regulatory Matters of the Exelon 2015 Form 10-K for additional information. PECO has contracts to procure electric supply that were executed through the competitive procurement process outlined in its PAPUC-approved DSP Programs, which are further discussed in Note 5 — Regulatory Matters . Based on Pennsylvania legislation and the DSP Programs permitting PECO to recover its electric supply procurement costs from retail customers with no mark-up, PECO’s price risk related to electric supply procurement is limited. PECO locked in fixed prices for a significant portion of its commodity price risk through full requirements contracts. PECO has certain full requirements contracts that are considered derivatives and qualify for the NPNS scope exception under current derivative authoritative guidance. PECO’s natural gas procurement policy is designed to achieve a reasonable balance of long-term and short-term gas purchases under different pricing approaches in order to achieve system supply reliability at the least cost. PECO’s reliability strategy is two-fold. First, PECO must assure that there is sufficient transportation capacity to satisfy delivery requirements. Second, PECO must ensure that a firm source of supply exists to utilize the capacity resources. All of PECO’s natural gas supply and asset management agreements that are derivatives either qualify for the NPNS scope exception and have been designated as such, or have no mark-to-market balances because the derivatives are index priced. Additionally, in accordance with the 2016 PAPUC PGC settlement and to reduce the exposure of PECO and its customers to natural gas price volatility, PECO has continued its program to purchase natural gas for both winter and summer supplies using a layered approach of locking-in prices ahead of each season with long-term gas purchase agreements (those with primary terms of at least twelve months). Under the terms of the 2016 PGC settlement, PECO is required to lock in (i.e. economically hedge) the price of a minimum volume of its long-term gas commodity purchases. PECO’s gas-hedging program is designed to cover about 25% of planned natural gas purchases in support of projected firm sales. The hedging program for natural gas procurement has no direct impact on PECO’s financial position or results of operations as natural gas costs are fully recovered from customers under the PGC. BGE has contracts to procure SOS electric supply that are executed through a competitive procurement process approved by the MDPSC. The SOS rates charged recover BGE's wholesale power supply costs and include an administrative fee. The administrative fee includes an incremental cost component and a shareholder return component for commercial and industrial rate classes. BGE’s price risk related to electric supply procurement is limited. BGE locks in fixed prices for all of its SOS requirements through full requirements contracts. Certain of BGE’s full requirements contracts, which are considered derivatives, qualify for the NPNS scope exception under current derivative authoritative guidance. Other BGE full requirements contracts are not derivatives. BGE provides natural gas to its customers under a MBR mechanism approved by the MDPSC. Under this mechanism, BGE’s actual cost of gas is compared to a market index (a measure of the market price of gas in a given period). The difference between BGE’s actual cost and the market index is shared equally between shareholders and customers. BGE must also secure fixed price contracts for at least 10% , but not more than 20% , of forecasted system supply requirements for flowing (i.e. non-storage) gas for the November through March period. These fixed-price contracts are not subject to sharing under the MBR mechanism. BGE also ensures it has sufficient pipeline transportation capacity to meet customer requirements. All of BGE’s natural gas supply and asset management agreements qualify for the NPNS scope exception and result in physical delivery. Pepco has contracts to procure SOS electric supply that are executed through a competitive procurement process approved by the MDPSC and DCPSC. The SOS rates charged recover Pepco's wholesale power supply costs and include an administrative fee. The administrative fee includes an incremental cost component and a shareholder return component for residential and commercial rate classes. Pepco’s price risk related to electric supply procurement is limited. Pepco locks in fixed prices for all of its SOS requirements through full requirements contracts. Certain of Pepco’s full requirements contracts, which are considered derivatives, qualify for the NPNS scope exception under current derivative authoritative guidance. Other Pepco full requirements contracts are not derivatives. DPL has contracts to procure SOS electric supply that are executed through a competitive procurement process approved by the MDPSC and the DPSC. The SOS rates charged recover DPL's wholesale power supply costs. In Delaware, DPL is also entitled to recover a Reasonable Allowance for Retail Margin (RARM). The RARM includes a fixed annual margin of approximately $2.75 million , plus an incremental cost component and a cash working capital allowance. In Maryland, DPL charges an administrative fee intended to allow it to recover its administrative costs. DPL locks in fixed prices for all of its SOS requirements through full requirements contracts. DPL’s price risk related to electric supply procurement is limited. Certain of DPL’s full requirements contracts, which are considered derivatives, qualify for the NPNS scope exception under current derivative authoritative guidance. Other DPL full requirements contracts are not derivatives. DPL provides natural gas to its customers under an Annual GCR mechanism approved by the DPSC. Under this mechanism, DPL’s Annual GCR Filing establishes a future GCR for firm bundled sales customers by using a forecast of demand and commodity costs. The actual costs are trued up versus the forecast on a monthly basis and any shortfall or excess is carried forward as a recovery balance in the next GCR filing. The demand portion of the GCR is based upon DPL’s firm transportation and storage contracts. DPL has firm deliverability of swing and seasonal storage; a liquefied natural gas facility and firm transportation capacity to meet customer demand and provide a reserve margin. The commodity portion of the GCR includes a commission approved hedging program which is intended to reduce gas commodity price volatility while limiting the firm natural gas customers’ exposure to adverse changes in the market price of natural gas. The hedge program requires that DPL hedge, on a non-discretionary basis, an amount equal to fifty percent (50%) of estimated purchase requirements for each month, including estimated monthly purchases for storage injections. The fifty percent (50%) hedge monthly target is achieved by hedging 1/12th of the 50% target each month beginning 12-months prior to the month in which the physical gas is to be purchased. Currently, DPL uses only exchange traded futures for its Gas Hedging Program, which are considered derivatives, however, it retains the capability to employ other physical and financial hedges if needed. DPL has not elected hedge accounting for these derivative financial instruments. Because of the DPSC-approved fuel adjustment clause for DPL's derivatives, the change in fair value of the derivatives each period, in addition to all premiums paid and other transaction costs incurred as part of the Gas Hedging Program, are fully recoverable and are recorded by DPL as regulatory assets or liabilities. DPL’s physical gas purchases are currently all daily, monthly or intra-month transactions. From time to time, DPL will enter into seasonal purchase or sale arrangements, however, there are none currently in the portfolio. Certain of DPL's full requirements contracts, which are considered derivatives, qualify for the NPNS scope exception under current derivative authoritative guidance. Other DPL full requirements contracts are not derivatives. ACE has contracts to procure BGS electric supply that are executed through a competitive procurement process approved by the NJBPU. The BGS rates charged recover ACE's wholesale power supply costs. ACE does not make any profit or incur any loss on the supply component of the BGS it supplies to customers. ACE’s price risk related to electric supply procurement is limited. ACE locks in fixed prices for all of its BGS requirements through full requirements contracts. Certain of ACE’s full requirements contracts, which are considered derivatives, qualify for the NPNS scope exception under current derivative authoritative guidance. Other ACE full requirements contracts are not derivatives. Proprietary Trading. Generation also enters into certain energy-related derivatives for proprietary trading purposes. Proprietary trading includes all contracts entered into with the intent of benefiting from shifts or changes in market prices as opposed to those entered into with the intent of hedging or managing risk. Proprietary trading activities are subject to limits established by Exelon’s RMC. The proprietary trading activities, which included settled physical sales volumes of 1,506 GWhs and 4,015 GWhs for the three and nine months ended September 30, 2016 , respectively, and 1,913 GWhs and 5,378 GWhs for the three and nine months ended September 30, 2015 , respectively, are a complement to Generation’s energy marketing portfolio but represent a small portion of Generation’s revenue from energy marketing activities. ComEd, PECO, BGE, PHI, Pepco, DPL and ACE do not enter into derivatives for proprietary trading purposes. Interest Rate and Foreign Exchange Risk (Exelon, Generation, ComEd, PECO, BGE and PHI) The Registrants use a combination of fixed-rate and variable-rate debt to manage interest rate exposure. The Registrants utilize fixed-to-floating interest rate swaps, which are typically designated as fair value hedges, as a means to manage their interest rate exposure. In addition, the Registrants may utilize interest rate derivatives to lock in rate levels in anticipation of future financings, which are typically designated as cash flow hedges. These strategies are employed to manage interest rate risks. At September 30, 2016 , Exelon had $800 million of notional amounts of fixed-to-floating hedges outstanding, and Exelon and Generation had $672 million of notional amounts of floating-to-fixed hedges outstanding. Assuming the fair value and cash flow interest rate hedges are 100% effective, a hypothetical 50 bps increase in the interest rates associated with unhedged variable-rate debt (excluding Commercial Paper) and fixed-to-floating swaps would result in an approximately $5 million decrease in Exelon Consolidated pre-tax income for the nine months ended September 30, 2016 . To manage foreign exchange rate exposure associated with international energy purchases in currencies other than U.S. dollars, Generation utilizes foreign currency derivatives, which are typically designated as economic hedges. Below is a summary of the interest rate and foreign exchange hedge balances as of September 30, 2016 . Generation Exelon Corporate Exelon Description Derivatives Designated as Hedging Instruments Economic Hedges Proprietary Trading (a) Collateral and Netting (b) Subtotal Derivatives Designated as Hedging Instruments Total Mark-to-market derivative assets (current assets) $ — $ 15 $ 4 $ (10 ) $ 9 $ — $ 9 Mark-to-market derivative assets (noncurrent assets) — 13 4 (11 ) 6 39 45 Total mark-to-market derivative assets — 28 8 (21 ) 15 39 54 Mark-to-market derivative liabilities (current liabilities) (8 ) (10 ) (3 ) 12 (9 ) — (9 ) Mark-to-market derivative liabilities (noncurrent liabilities) (10 ) (9 ) (3 ) 12 (10 ) — (10 ) Total mark-to-market derivative liabilities (18 ) (19 ) (6 ) 24 (19 ) — (19 ) Total mark-to-market derivative net assets (liabilities) $ (18 ) $ 9 $ 2 $ 3 $ (4 ) $ 39 $ 35 _________ (a) Generation enters into interest rate derivative contracts to economically hedge risk associated with the interest rate component of commodity positions. The characterization of the interest rate derivative contracts between the proprietary trading activity in the above table is driven by the corresponding characterization of the underlying commodity position that gives rise to the interest rate exposure. Generation does not utilize proprietary trading interest rate derivatives with the objective of benefiting from shifts or changes in market interest rates. (b) Exelon and Generation net all available amounts allowed under the derivative accounting guidance on the balance sheet. These amounts include unrealized derivative transactions with the same counterparty under legally enforceable master netting agreements and cash collateral. In some cases Exelon and Generation may have other offsetting exposures, subject to a master netting or similar agreement, such as accrued interest, transactions that do not qualify as derivatives, letters of credit and other forms of non-cash collateral. These are not reflected in the table above. The following table provides a summary of the interest rate and foreign exchange hedge balances recorded by the Registrants as of December 31, 2015 : Generation Exelon Corporate Exelon Description Derivatives Designated as Hedging Instruments Economic Hedges Proprietary Trading (a) Collateral and Netting (b) Subtotal Derivatives Designated as Hedging Instruments Total Mark-to-market derivative assets (current assets) $ — $ 10 $ 10 $ (5 ) $ 15 $ — $ 15 Mark-to-market derivative assets (noncurrent assets) — 10 5 (1 ) 14 25 39 Total mark-to-market derivative assets — 20 15 (6 ) 29 25 54 Mark-to-market derivative liabilities (current liabilities) (8 ) (2 ) (9 ) 11 (8 ) — (8 ) Mark-to-market derivative liabilities (noncurrent liabilities) (8 ) (1 ) (3 ) 4 (8 ) — (8 ) Total mark-to-market derivative liabilities (16 ) (3 ) (12 ) 15 (16 ) — (16 ) Total mark-to-market derivative net assets (liabilities) $ (16 ) $ 17 $ 3 $ 9 $ 13 $ 25 $ 38 __________ (a) Generation enters into interest rate derivative contracts to economically hedge risk associated with the interest rate component of commodity positions. The characterization of the interest rate derivative contracts between the proprietary trading activity in the above table is driven by the corresponding characterization of the underlying commodity position that gives rise to the interest rate exposure. Generation does not utilize proprietary trading interest rate derivatives with the objective of benefiting from shifts or changes in market interest rates. (b) Exelon and Generation net all available amounts allowed under the derivative accounting guidance on the balance sheet. These amounts include unrealized derivative transactions with the same counterparty under legally enforceable master netting agreements and cash collateral. In some cases Exelon and Generation may have other offsetting exposures, subject to a master netting or similar agreement, such as accrued interest, transactions that do not qualify as derivatives, letters of credit and other forms of non-cash collateral. These are not reflected in the table above. Fair Value Hedges . For derivative instruments that are designated and qualify as fair value hedges, the gain or loss on the derivative as well as the offsetting loss or gain on the hedged item attributable to the hedged risk are recognized in current earnings. Exelon includes the gain or loss on the hedged items and the offsetting loss or gain on the related interest rate swaps in interest expense as follows: Three Months Ended September 30, Income Statement Location 2016 2015 2016 2015 Gain (loss) on Swaps Gain (loss) on Borrowings Exelon Interest expense $ (8 ) $ 16 $ 14 $ (13 ) Nine Months Ended September 30, Income Statement Location 2016 2015 2016 2015 Gain (loss) on Swaps Gain (loss) on Borrowings Generation Interest expense (a) $ — $ (1 ) $ — $ — Exelon Interest expense 15 15 (3 ) (4 ) __________ (a) For the nine months ended September 30, 2015 , the loss on Generation swaps included $1 million realized in earnings with an immaterial amount excluded from hedge effectiveness testing. At September 30, 2016 , Exelon had total outstanding fixed-to-floating fair value hedges related to interest rate swaps of $800 million , with a derivative asset of $39 million . At December 31, 2015 , Exelon had total outstanding fixed-to-floating fair value hedges related to interest rate swaps of $800 million , with a derivative asset of $25 million . During the three and nine months ended September 30, 2016 , the impact on the results of operations as a result of ineffectiveness from fair value hedges was a $6 million and a $12 million gain, respectively. Cash Flow Hedges . During the second quarter of 2016, Exelon entered into $90 million of floating-to-fixed forward starting interest rate swaps to manage a portion of the interest rate exposure associated with an anticipated debt issuance. The swaps were designated as cash flow hedges. Exelon terminated the swaps during the third quarter of 2016 upon issuance of the debt. Exelon did not recognize a gain or loss as a result of the termination. During the first and second quarter of 2016, Exelon entered into $600 million and $100 million of floating-to-fixed forward starting interest rate swaps, respectively, to manage a portion of the interest rate exposure associated with the anticipated issuance of debt. The swaps were designated as cash flow hedges. Exelon terminated the swaps during the second quarter of 2016 upon issuance of the debt. Exelon recognized a loss of $3 million related to the swaps and $3 million of AOCI will be amortized into Other, net in Exelon's Consolidated Statement of Operations and Comprehensive Income over the term of the debt. See Note 10 — Debt and Credit Agreements for additional information. During the first quarter of 2016, Exelon entered into $100 million of floating-to-fixed forward starting interest rate swap to manage a portion of the interest rate exposure associated with an anticipated debt issuance. The swap was designated as a cash flow hedge. Exelon terminated the swap during the first quarter of 2016 upon issuance of the debt. Exelon did not recognize a gain or loss as a result of the termination of the swap and an immaterial amount of AOCI will be amortized into Other, net in Exelon's Consolidated Statement of Operations and Comprehensive Income over the term of the debt. During the third quarter of 2014, ExGen Texas Power, LLC, a subsidiary of Generation, entered into a floating-to-fixed interest rate swap to manage a portion of its interest rate exposure in connection with the long-term borrowing. See Note 14 — Debt and Credit Agreements of the Exelon 2015 Form 10-K for additional information regarding the financing. The swaps have a notional amount of $496 million as of September 30, 2016 and expire in 2019. The swap was designated as a cash flow hedge in the fourth quarter of 2014. At September 30, 2016 , the subsidiary had a $15 million derivative liability related to the swap. During the first quarter of 2014, ExGen Renewables I, LLC, a subsidiary of Generation, entered into floating-to-fixed interest rate swaps to manage a portion of its interest rate exposure in connection with the long-term borrowings. See Note 14 — Debt and Credit Agreements of the Exelon 2015 Form 10-K for additional information regarding the financing. The swaps have a notional amount of $176 million as of September 30, 2016 and expire in 2020. The swaps are designated as cash flow hedges. At September 30, 2016 , the subsidiary had a $3 million derivative liability related to the swaps. During the second quarter of 2002, PHI entered into treasury rate lock transactions in anticipation of the issuance of several series of fixed-rate debt commencing in August 2002 to manage a portion of its interest rate exposure. Upon issuance of the fixed-rate debt in August 2002, the treasury rate locks were terminated at a loss and the loss was deferred in AOCI. As a result of the PHI Merger, the remaining unamortized deferred loss recorded in AOCI was adjusted to zero through application of purchase accounting. During the three and nine months ended September 30, 2016 and 2015 , the impact on the results of operations as a result of ineffectiveness from cash flow hedges in continuing designated hedge relationships was immaterial. Economic Hedges . During the third quarter of 2011, Sacramento PV Energy, a subsidiary of Generation entered into floating-to-fixed interest rate swaps to manage a portion of its interest rate exposure in connection with the long-term borrowings. See Note 14 — Debt and Credit Agreements of the Exelon 2015 Form 10-K for additional information regarding the financing. During the first quarter of 2016, upon the issuance of debt, Generation terminated the swaps. The total notional amount of the swaps were $25 million . No gain or loss was recognized as a result of the termination of the swaps. During the third quarter of 2012, Constellation Solar Horizons, a subsidiary of Generation, entered into a floating-to-fixed interest rate swap to manage a portion of its interest rate exposure in connection with the long-term borrowings. See Note 14 — Debt and Credit Agreements of the Exelon 2015 Form 10-K for additional information regarding the financing. During the first quarter of 2016, upon the issuance of debt, Generation terminated the swap. The total notional amount of the swap was $24 million . No gain or loss was recognized as a result of the termination of the swap. During the second quarter 2015, upon the issuance of debt, Exelon terminated $2,400 million of floating-to-fixed forward starting interest rate swaps. As a result of the termination of the swaps, Exelon realized a $64 million loss during the second quarter of 2015. At September 30, 2016 , Generation had no notional amounts of interest rate derivative contracts to economically hedge risk associated with the interest rate component of commodity positions and $85 million in notional amounts of foreign currency exchange rate swaps that are marked-to-market to manage the exposure associated with international commodity transactions in currencies other than U.S. dollars. Fair Value Measurement and Accounting for the Offsetting of Amounts Related to Certain Contracts (Exelon, Generation, ComEd, PECO, BGE, PHI and DPL) Fair value accounting guidance and disclosures about offsetting assets and liabilities requires the fair value of derivative instruments to be shown in the Notes to the Consolidated Financial Statements on a gross basis, even when the derivative instruments are subject to legally enforceable master netting agreements and qualify for net presentation in the Consolidated Balance Sheet. A master netting agreement is an agreement between two counterparties that may have derivative and non-derivative contracts with each other providing for the net settlement of all referencing contracts via one payment stream, which takes place as the contracts deliver, when collateral is requested or in the event of default. Generation’s use of cash collateral is generally unrestricted, unless Generation is downgraded below investment grade (i.e. to BB+ or Ba1). In the table below, Generation’s energy related economic hedges and proprietary trading derivatives are shown gross. The impact of the netting of fair value balances with the same counterparty that are subject to legally enforceable master netting agreements, as well as netting of cash collateral, including initial margin on exchange positions, is aggregated in the collateral and netting column. As of September 30, 2016 and December 31, 2015 , $5 million and $3 million of cash collateral held and posted, respectively, was not offset against derivative positions because such collateral was not associated with any energy-related derivatives, were associated with accrual positions, or as of the balance sheet date there were no positions to offset. Excluded from the tables below are economic hedges that qualify for the NPNS scope exception and other non-derivative contracts that are accounted for under the accrual method of accounting. ComEd’s use of cash collateral is generally unrestricted unless ComEd is downgraded below investment grade (i.e. to BB+ or Ba1). Cash collateral held by PECO and BGE must be deposited in a non affiliate major U.S. commercial bank or foreign bank with a U.S. branch office that meet certain qualifications. In the table below, DPL's economic hedges are shown gross. The impact of the netting of fair value balances with the same counterparty that are subject to legally enforceable master netting agreements, as well as netting of cash collateral, is aggregated in the collateral and netting column. The following table provides a summary of the derivative fair value balances recorded by the Registrants as of September 30, 2016 : Successor Generation ComEd DPL PHI Exelon Derivatives Economic Hedges Proprietary Trading Collateral and Netting (a) Subtotal (b) Economic Hedges (c) Economic Hedges (d) Collateral and Netting (a) Subtotal Subtotal Total Derivatives Mark-to-market derivative assets (current assets) $ 3,482 $ 67 $ (2,804 ) $ 745 $ — $ 1 $ (1 ) $ — $ — $ 745 Mark-to-market derivative assets (noncurrent assets) 2,139 31 (1,546 ) 624 — — — — — 624 Total mark-to-market derivative assets 5,621 98 (4,350 ) 1,369 — 1 (1 ) — — 1,369 Mark-to-market derivative liabilities (current liabilities) (3,229 ) (61 ) 3,096 (194 ) (19 ) — — — — (213 ) Mark-to-market derivative liabilities (noncurrent liabilities) (1,885 ) (41 ) 1,739 (187 ) (225 ) — — — — (412 ) Total mark-to-market derivative liabilities (5,114 ) (102 ) 4,835 (381 ) (244 ) — — — — (625 ) Total mark-to-market derivative net assets (liabilities) $ 507 $ (4 ) $ 485 $ 988 $ (244 ) $ 1 $ (1 ) $ — $ — $ 744 ______ (a) Exelon, Generation, PHI and DPL net all available amounts allowed

Debt and Credit Agreements (All

Debt and Credit Agreements (All Registrants)	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Debt and Credit Agreements (All Registrants)	10 . Debt and Credit Agreements (All Registrants) Short-Term Borrowings Exelon, ComEd, and BGE meet their short-term liquidity requirements primarily through the issuance of commercial paper. Generation and PECO meet their short-term liquidity requirements primarily through the issuance of commercial paper and borrowings from the Exelon intercompany money pool. PHI meets its short-term liquidity requirement primarily through the issuance of short-term notes and the Exelon intercompany money pool. Pepco, DPL and ACE meet their short-term liquidity requirements primarily through the issuance of commercial paper and short-term notes. Commercial Paper The Registrants had the following amounts of commercial paper borrowings outstanding as of September 30, 2016 and December 31, 2015 : Commercial Paper Borrowings September 30, 2016 December 31, 2015 ComEd $ 10 $ 294 BGE — 210 PHI Corporate — 484 Pepco — 64 DPL 17 105 ACE — 5 Short-Term Loan Agreements On July 30, 2015, PHI entered into a $300 million term loan agreement. The net proceeds of the loan were used to repay PHI's outstanding commercial paper and for general corporate purposes. Pursuant to the loan agreement, loans made thereunder bear interest at a variable rate equal to LIBOR plus 0.95%, and all indebtedness thereunder is unsecured. On April 4, 2016, PHI repaid $300 million of its term loan in full. On January 13, 2016, PHI entered into a $500 million term loan agreement, which was amended on March 28, 2016. The net proceeds of the loan were used to repay PHI's outstanding commercial paper, and for general corporate purposes. Pursuant to the loan agreement, as amended, loans made thereunder bear interest at a variable rate equal to LIBOR plus 1% , and all indebtedness thereunder is unsecured, and the aggregate principal amount of all loans, together with any accrued but unpaid interest due under the loan agreement, must be repaid in full on or before March 27, 2017. The loan agreement is reflected in Exelon's and PHI's Consolidated Balance Sheets within Short-term borrowings. On February 22, 2016, Generation and EDF entered into separate member revolving promissory notes with CENG to finance short-term working capital needs. The notes are scheduled to mature on January 31, 2017 and bear interest at a variable rate equal to LIBOR plus 1.75% . On July 25, 2016, CENG paid off the outstanding balances under each note. Credit Agreements On January 5, 2016, Generation entered into a credit agreement establishing a $150 million bilateral credit facility, scheduled to mature in January of 2019. This facility will solely be utilized by Generation to issue letters of credit. This facility does not back Generation's commercial paper program. On April 1, 2016, the credit agreement for CENG's $100 million bilateral credit facility was amended to increase the overall facility size to $200 million . This facility is utilized by CENG to fund working capital and capital projects. The facility does not back Generation's commercial paper program. On May 26, 2016, Exelon Corporate, Generation, ComEd, PECO and BGE entered into amendments to each of their respective syndicated revolving credit facilities, which extended the maturity of each of the facilities to May 26, 2021. Exelon Corporate also increased the size of its facility from $500 million to $600 million . On May 26, 2016, PHI, Pepco, DPL and ACE entered into an amendment to their Second Amended and Restated Credit Agreement dated as of August 1, 2011, which (i) extended the maturity date of the facility to May 26, 2021, (ii) removed PHI as a borrower under the facility, (iii) decreased the size of the facility from $1.5 billion to $900 million and (iv) aligned its financial covenant from debt to capitalization leverage ratio to interest coverage ratio. Variable Rate Demand Bonds As of September 30, 2016 and December 31, 2015 , $105 million in variable rate demand bonds issued by DPL were outstanding and are included in the Long-term debt due within one year on Exelon's, PHI's and DPL's Consolidated Balance Sheets. See Note 10 - Debt of the PHI 2015 Form 10-K for additional information. Long-Term Debt Issuance of Long-Term Debt During the nine months ended September 30, 2016 , the following long-term debt was issued: Company Type Interest Rate Maturity Amount Use of Proceeds Exelon Corporate Senior Unsecured Notes 2.45 % April 15, 2021 $ 300 Repay commercial paper issued by PHI and for general corporate purposes Exelon Corporate Senior Unsecured Notes 3.40 % April 15, 2026 $ 750 Repay commercial paper issued by PHI and for general corporate purposes Exelon Corporate Senior Unsecured Notes 4.45 % April 15, 2046 $ 750 Repay commercial paper issued by PHI and for general corporate purposes Generation Renewable Power Generation Nonrecourse Debt 4.11 % March 31, 2035 $ 150 Paydown long term debt obligations at Sacramento PV Energy and Constellation Solar Horizons and for general corporate purposes Generation Albany Green Energy Project Financing LIBOR + 1.25% November 17, 2017 $ 86 Albany Green Energy biomass generation development Generation Energy Efficiency Project Financing 3.17 % December 31, 2017 $ 16 Funding to install energy conservation measures in Brooklyn, NY Generation Energy Efficiency Project Financing 3.42 % January 31, 2018 $ 13 Funding to install energy conservation measures for the Naval Station Great Lakes project ComEd First Mortgage Bonds, Series 120 2.55 % June 15, 2026 $ 500 Refinance maturing mortgage bonds, repay a portion of ComEd's outstanding commercial paper obligations and for general corporate purposes ComEd First Mortgage Bonds, Series 121 3.65 % June 15, 2046 $ 700 Refinance maturing mortgage bonds, repay a portion of ComEd's outstanding commercial paper obligations and for general corporate purposes Generation Energy Efficiency Project Financing 3.52 % April 30, 2018 $ 11 Funding to install energy conservation measures for the Smithsonian Zoo project Pepco Energy Efficiency Project Financing 3.30 % December 15, 2017 $ 2 Funding to install energy conservation measures for the DOE Germantown project BGE Notes 2.40 % August 15, 2026 $ 350 Redeem the $190M of outstanding preference shares and for general corporate purposes BGE Notes 3.50 % August 15, 2046 $ 500 Redeem the $190M of outstanding preference shares and for general corporate purposes PECO (a) First Mortgage Bonds 1.70 % September 15, 2021 $ 300 Refinance maturing mortgage bonds Generation SolGen Nonrecourse Debt 3.93 % September 30, 2036 $ 150 General corporate purposes Generation ExGen Texas Power Nonrecourse Debt LIBOR + 4.25% September 18, 2019 $ 4 General corporate purposes for EGTP ________________ (a) Includes rest ricted proceeds of $30 million shown in the Restricted proceeds from issuance of long-term debt on Exelon’s and PECO’s Cash Flow Statements and Restricted cash and cash equivalents on Exelon’s and PECO’s Consolidated Balance Sheets. The restricted proceeds were used as a portion of the payment on the maturing mortgage bonds due October 15, 2016, and as of that date, the restriction is no longer in place. CEU Upstream Nonrecourse Debt In July 2011, CEU Holdings, LLC, a wholly owned subsidiary of Generation, entered into a 5-year reserve based lending agreement (RBL) associated with certain Upstream oil and gas properties that it owns. The lenders do not have recourse against Exelon or Generation in the event of default pursuant to the RBL. Borrowings under this arrangement are secured by the assets and equity of CEU Holdings. The commitment level can be decreased if the assets no longer support the current borrowing base, which may result in repayment of a portion or all of the outstanding balance, or potential foreclosure of the assets. The commitment can be increased up to $500 million if the assets support a higher borrowing base and CEU Holdings is able to obtain additional commitments from lenders. Calculations of the borrowing base are impacted by projected production and commodity prices. The facility was amended and extended on January 14, 2014 through January 2019. As of December 31, 2015 , $68 million was outstanding under the facility with interest payable monthly at a variable rate equal to LIBOR plus 2.50% and the borrowing base committed under the facility was $85 million . The outstanding balance was classified as Long-term debt on Exelon's and Generation's Consolidated Balance Sheets. In February 2016, as part of their semi-annual borrowing base re-determination testing, the RBL lenders notified CEU Holdings that the RBL borrowing base was decreased to $45 million , resulting in a “borrowing base deficiency” under the RBL of $23 million . Given the decline in value of the Upstream assets resulting from lower commodity prices, CEU Holdings chose not to provide the lenders with a formal plan for curing the borrowing base deficiency by March 31, 2016, as was required by the RBL. The lenders have sent CEU Holdings a notice of event of default and demand for cure. On March 31, 2016, $7 million of the debt was repaid using CEU Holding's cash, resulting in an outstanding debt balance of $61 million with interest payable monthly at a variable rate equal to LIBOR plus 2.75% and a borrowing base deficiency under the RBL of $16 million . At March 31, 2016, the outstanding debt balance of $61 million was classified within Long-term debt due within one year on Exelon's and Generation's Consolidated Balance Sheets. On June 16, 2016, CEU Holdings executed a forbearance agreement with the lenders which included terms stipulating roles and responsibilities governing a sales process, approval of the sale of the assets to be at the discretion of the lenders, and a sales timetable, with ultimate execution of the sales agreement expected to occur by December 31, 2016. Upon disposition of the assets and the satisfaction of certain other conditions, CEU Holdings will be released of its obligations regardless of the amount of asset sale proceeds received. The ultimate resolution of this matter has no direct effect on any Exelon or Generation credit facilities or other debt of an Exelon entity. See Note 14 - Debt and Credit Agreements of the Exelon 2015 Form 10-K, Note 5 - Mergers, Acquisitions and Dispositions and Note 6 - Impairment of Long-Lived Assets for additional information.

Income Taxes (All Registrants)

Income Taxes (All Registrants)	9 Months Ended
	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes (All Registrants)	Income Taxes (All Registrants) The effective income tax rate from continuing operations varies from the U.S. Federal statutory rate principally due to the following: Three Months Ended September 30, 2016 Successor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE U.S. Federal statutory rate 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% Increase (decrease) due to: State income taxes, net of Federal income tax benefit 3.8 2.6 7.3 2.4 5.2 5.6 5.6 5.2 6.1 Qualified nuclear decommissioning trust fund income 4.0 7.8 — — — — — — — Domestic production activities deduction — — — — — — — — — Health care reform legislation — — — — — — — — — Amortization of investment tax credit, net deferred taxes (0.9) (1.6) (0.6) (0.1) (0.2) (0.1) — (0.2) (0.1) Plant basis differences (3.0) — (1.9) (6.7) (0.5) (5.0) (6.7) (1.3) (4.6) Production tax credits and other credits (2.9) (5.7) (0.1) — — — — — — Noncontrolling interests 0.2 0.5 — — — — — — — Statute of limitations expiration (0.1) 0.3 — — — — — — — Penalties 4.3 — 27.2 — — — — — — Merger expenses (0.6) — — — — (5.7) (2.3) (8.6) (2.9) Other (0.8) (0.5) 0.1 0.1 (0.4) (0.7) (0.9) 0.1 (0.6) Effective income tax rate 39.0% 38.4% 67.0% 30.7% 39.1% 29.1% 30.7% 30.2% 32.9% Three Months Ended September 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE U.S. Federal statutory rate 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% Increase (decrease) due to: State income taxes, net of Federal income tax benefit 2.7 2.1 5.0 1.2 5.3 6.2 4.8 7.4 5.4 Qualified nuclear decommissioning trust fund income (5.4) (12.5) — — — — — — — Domestic production activities deduction (4.9) (11.6) — — — — — — — Health care reform legislation — — — — 0.2 — — — — Amortization of investment tax credit, net deferred taxes (2.3) (5.2) (0.3) (0.1) (0.2) (0.2) (0.1) (0.6) (0.3) Plant basis differences (1.4) — (0.1) (7.0) (0.6) (3.7) (3.5) (3.5) (3.1) Production tax credits and other credits (3.8) (9.0) — — — (1.2) — — — Noncontrolling interests 1.7 3.9 — — — — — — — Statute of limitations expiration (6.4) (15.2) — — — — — — — Other 1.2 0.4 0.3 — (0.4) (1.1) (1.4) (0.8) 1.9 Effective income tax rate 16.4% (12.1)% 39.9% 29.1% 39.3% 35.0% 34.8% 37.5% 38.9% Successor Predecessor Nine Months Ended September 30, 2016 March 24, 2016 to September 30, 2016 January 1, 2016 to March 23, 2016 Exelon Generation ComEd PECO BGE Pepco DPL (a) ACE (a) PHI (a) PHI U.S. Federal statutory rate 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% Increase (decrease) due to: State income taxes, net of Federal income tax benefit (b) 2.5 2.6 5.4 1.3 4.8 23.0 310.5 5.5 4.4 11.9 Qualified nuclear decommissioning trust fund income 4.8 8.8 — — — — — — — — Domestic production activities deduction — — — — — — — — — — Health care reform legislation — — — — — — — — — — Amortization of investment tax credit, including deferred taxes on basis difference (1.3) (2.0) (0.3) (0.1) (0.2) (0.2) (17.9) 0.5 0.5 (0.9) Plant basis differences (4.5) — (0.6) (8.8) (3.3) (29.0) (98.6) 7.8 17.5 (13.5) Production tax credits and other credits (4.1) (7.6) — — — — — — — — Noncontrolling interests 0.5 0.9 — — — — — — — — Statute of limitations expiration (0.5) (1.7) — — — — — — — Penalties 2.3 — 5.6 — — — — — — Merger expenses 6.2 — — — — 36.7 635.9 (35.4) (49.8) 11.1 Other (c) (1.8) (2.1) — (1.5) — (2.5) 35.1 0.4 1.4 3.6 Effective income tax rate 39.1% 33.9% 45.1% 25.9% 36.3% 63.0% 900.0% 13.8% 9.0% 47.2% Nine Months Ended September 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE U.S. Federal statutory rate 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% Increase (decrease) due to: State income taxes, net of Federal income tax benefit 3.1 2.8 5.2 1.2 5.3 7.1 4.6 6.1 5.5 Qualified nuclear decommissioning trust fund income (0.9) (1.6) — — — — — — — Domestic production activities deduction (2.8) (4.9) — — — — — — — Health care reform legislation — — — — 0.2 — — — — Amortization of investment tax credit, including deferred taxes on basis difference (1.2) (1.9) (0.3) (0.1) (0.1) (0.3) (0.1) (0.4) (0.5) Plant basis differences (1.2) — (0.1) (7.3) (0.4) (5.0) (6.2) (2.0) (2.5) Production tax credits and other credits (2.2) (3.8) — — — (1.9) — — — Noncontrolling interests — 0.1 — — — — — — — Statute of limitations expiration (1.6) (2.9) — — — — — — — Other 0.9 0.6 0.2 0.2 (0.1) (0.1) (0.7) (0.5) 0.8 Effective income tax rate 29.1% 23.4% 40.0% 29.0% 39.9% 34.8% 32.6% 38.2% 38.3% (a) DPL and ACE recognized a loss before income taxes for the nine months ended September 30, 2016 , and PHI recognized a loss before income taxes for the period of March 24, 2016, through September 30, 2016 . As a result, positive percentages represent an income tax benefit for the periods presented. (b) Includes a remeasurement of uncertain state income tax positions for Pepco and DPL. (c) At PECO, includes a cumulative adjustment related to an anticipated gas repairs tax return accounting method change. Accounting for Uncertainty in Income Taxes The Registrants have the following unrecognized tax benefits as of September 30, 2016 and December 31, 2015 : Successor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE September 30, 2016 $ 937 $ 516 $ (12 ) $ — $ 120 $ 157 $ 79 $ 34 $ 22 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE December 31, 2015 $ 1,101 $ 534 $ 142 $ — $ 120 $ 22 $ 8 $ 3 $ — Exelon and ComEd’s unrecognized tax benefits changed by $ 328 million and $ 154 million , respectively, as of September 30, 2016 as a result of the lease termination on the like-kind exchange position discussed below. In addition, as a result of the merger, an assessment and remeasurement of certain federal and state uncertain income tax positions resulted in an increase in unrecognized tax benefits at Exelon, PHI, Pepco, DPL and ACE of $164 million , $135 million , $71 million , $31 million and $22 million , respectively. Reasonably possible the total amount of unrecognized tax benefits could significantly increase or decrease within 12 months after the reporting date Settlement of Income Tax Audits and Litigation As of September 30, 2016 , Exelon, Generation, BGE, PHI, Pepco, and DPL have approximately $251 million , $ 52 million , $120 million , $ 79 million , $ 59 million , and $ 20 million of unrecognized federal and state tax benefits that could significantly decrease within the 12 months after the reporting date as a result of completing audits and potential settlements. Of the above unrecognized tax benefits, Exelon and Generation have $ 52 million that, if recognized, would decrease the effective tax rate. The unrecognized tax benefits related to BGE, DPL, and a portion of Pepco, if recognized, may be included in future regulated base rates and that portion would have no impact to the effective tax rate. Other Income Tax Matters Like-Kind Exchange (Exelon and ComEd) Exelon, through its ComEd subsidiary, took a position on its 1999 income tax return to defer approximately $ 1.2 billion of tax gain on the sale of ComEd’s fossil generating assets. The gain was deferred by reinvesting a portion of the proceeds from the sale in qualifying replacement property under the like-kind exchange provisions of the IRC. The like-kind exchange replacement property purchased by Exelon included interests in three municipal-owned electric generation facilities which were properly leased back to the municipalities. The IRS disagreed with this position and asserted that the entire gain of approximately $ 1.2 billion was taxable in 1999. Exelon was unable to reach agreement with the IRS regarding the dispute over the like-kind exchange position. The IRS asserted that the Exelon purchase and leaseback transaction was substantially similar to a leasing transaction, known as a SILO, which the IRS does not respect as the acquisition of an ownership interest in property. A SILO is a “listed transaction” that the IRS has identified as a potentially abusive tax shelter under guidance issued in 2005. Accordingly, the IRS asserted that the sale of the fossil plants followed by the purchase and leaseback of the municipal owned generation facilities did not qualify as a like-kind exchange and the gain on the sale is fully subject to tax. The IRS also asserted a penalty of approximately $ 90 million for a substantial understatement of tax. In accordance with applicable accounting standards, Exelon was required to assess whether it was more-likely-than-not that to prevail in litigation. In light of the outcome of another case involving a listed transaction and Exelon’s determination that settlement was unlikely, Exelon concluded that subsequent to December 31, 2012, it was no longer more-likely-than-not that its position would be sustained. As a result, in the first quarter of 2013 Exelon recorded a non-cash charge to earnings of approximately $ 265 million , which represented the amount of interest expense (after-tax) and incremental state income tax expense for periods through March 31, 2013, that would be payable in the event that Exelon is unsuccessful in litigation. Of this amount, approximately $ 172 million was recorded at ComEd. Exelon has agreed to hold ComEd harmless from any unfavorable impacts on ComEd’s equity of the after-tax interest or penalty amounts. As a result, ComEd recorded on its consolidated balance sheet as of March 31, 2013, a $ 172 million receivable and non-cash equity contributions from Exelon. Based on applicable case law and the facts of the transaction, Exelon did not believe it was likely a penalty would be assessed. Accordingly, no charge was recorded for the penalty asserted nor for after-tax interest that could be due on the asserted penalty. On September 30, 2013, the IRS issued a notice of deficiency to Exelon for the like-kind exchange position. Exelon filed a petition on December 13, 2013 to initiate litigation in the United States Tax Court and the trial took place in August of 2015. Exelon was not required to remit any part of the asserted tax or penalty in order to litigate the issue. On September 19, 2016, the Tax Court rejected Exelon’s position in the case and ruled that Exelon was not entitled to defer gain on the transaction. In addition, contrary to Exelon’s evaluation that the penalty was unwarranted, the Tax Court ruled that Exelon is liable for the penalty and interest due on the asserted penalty. In early 2017, Exelon expects to timely appeal this decision to the U.S. Court of Appeals for the Seventh Circuit. While it has strong arguments on appeal with respect to both the merits and the penalty, Exelon has determined that, pursuant to accounting standards, it is no longer more-likely-than-not to avoid the penalty. As a result, in the third quarter of 2016, Exelon recorded a charge to earnings for the penalty and the after-tax interest due on the asserted penalty of approximately $ 200 million , of which approximately $ 150 million was recorded at ComEd. Exelon and ComEd recorded the penalty and interest due on the asserted penalty to Other, net and Interest expense, net, respectively, on their Consolidated Statements of Operations. Consistent with Exelon’s agreement to continue to hold ComEd harmless from any unfavorable impact on its equity, ComEd recorded on its consolidated balance sheet as of September 30, 2016 , a $ 150 million receivable and non-cash equity contributions from Exelon. In order to appeal the decision, Exelon is required to pay the tax, penalties and interest at the time Exelon files its appeal (expected early 2017). While the final calculation of tax, penalties and interest has not yet been finalized by the IRS, Exelon estimates that a payment of approximately $ 1.4 billion related to the like-kind exchange will be due, including $ 300 million from ComEd, in the first quarter of 2017. While Exelon will receive a tax benefit of $ 400 million associated with the deduction for the interest, Exelon currently has a net operating loss carryforward and thus does not expect to realize the cash benefit until 2018. After taking into account these interest deduction tax benefits, the total estimated net cash outflow for the like-kind exchange is $ 1 billion , of which approximately $ 300 million is attributable to ComEd after giving consideration to Exelon’s agreement to hold ComEd harmless from any unfavorable impacts of after-tax interest or penalty amounts on ComEd’s equity. Upon a final appellate decision, which could take up to several years, Exelon expects to receive $ 80 million related to final interest computations . As of September 30, 2016 , ComEd has a total receivable from Exelon pursuant to the hold harmless agreement of $ 345 million , which is included in Current Receivables from Affiliates on ComEd’s Consolidated Balance Sheet. Under the agreement, Exelon will settle this receivable with ComEd no later than the time that the payments related to the like-kind exchange are due to the IRS, currently anticipated in first quarter 2017. Exelon will not seek recovery from ComEd customers for any interest or penalty amounts associated with the like-kind exchange tax position. As previously disclosed, in the first quarter of 2014, Exelon entered into an agreement to terminate its investment in one of the three municipal-owned electric generation properties in exchange for a net early termination amount of $ 335 million . On March 31, 2016, Exelon entered into an agreement to terminate its interests in the remaining two municipal-owned electric generation properties in exchange for $ 360 million . Long-Term State Tax Apportionment (Exelon, Generation and PHI) Exelon, Generation and PHI periodically review events that may significantly impact how income is apportioned among the states and, therefore, the calculation of their respective deferred state income taxes. Events that may require Exelon, Generation and PHI to update their long-term state tax apportionment include significant changes in tax law and/or significant operational changes, such as the merger with PHI. As a result of the merger, Exelon and Generation reevaluated their long-term state tax apportionment for all states where they have state income tax obligations, which include Delaware, Illinois, Maryland, New Jersey, Pennsylvania, and Washington D.C., as well as other states. The total effect of revising the long-term state tax apportionment resulted in the recording of deferred state tax benefit in the amount of $1 million and a state tax expense of $6 million , net of tax, for Exelon and Generation, respectively. Further, Exelon and PHI recorded deferred state tax liabilities of $ 59 million and $ 8 million , net of tax, respectively, as part of purchase accounting during the first quarter of 2016.

Nuclear Decommissioning (Exelon

Nuclear Decommissioning (Exelon and Generation)	9 Months Ended
	Sep. 30, 2016
Environmental Remediation Obligations [Abstract]
Nuclear Decommissioning (Exelon and Generation)	Nuclear Decommissioning (Exelon and Generation) Nuclear Decommissioning Asset Retirement Obligations Generation has a legal obligation to decommission its nuclear power plants following the expiration of their operating licenses. To estimate its decommissioning obligation related to its nuclear generating stations for financial accounting and reporting purposes, Generation uses a probability-weighted, discounted cash flow model which, on a unit-by-unit basis, considers multiple outcome scenarios that include significant estimates and assumptions, and are based on decommissioning cost studies, cost escalation rates, probabilistic cash flow models and discount rates. Generation updates its ARO annually, unless circumstances warrant more frequent updates, based on its review of updated cost studies and its annual evaluation of cost escalation factors and probabilities assigned to various scenarios. The following table provides a rollforward of the nuclear decommissioning ARO reflected on Exelon’s and Generation’s Consolidated Balance Sheets from December 31, 2015 to September 30, 2016 : Nuclear decommissioning ARO at December 31, 2015 (a) $ 8,246 Accretion expense 325 Net increase due to changes in, and timing of, estimated cash flows 444 Costs incurred to decommission retired plants (6 ) Nuclear decommissioning ARO at September 30, 2016 (a) $ 9,009 _________ (a) Includes $44 million and $7 million for the current portion of the ARO at September 30, 2016 and December 31, 2015 , respectively, which is included in Other current liabilities on Exelon’s and Generation’s Consolidated Balance Sheets. During the nine months ended September 30, 2016 , Generation’s nuclear ARO increased by approximately $ 763 million , reflecting impacts of ARO updates completed during the first and second quarters of 2016 to reflect changes in amounts and timing of estimated decommissioning cash flows and impacts of year-to-date accretion of the ARO liability due to the passage of time. In 2016, the ARO liability increased by $ 444 million primarily driven by an increase of $ 384 million associated with the June 2, 2016 announcement to early retire the Clinton and Quad Cities nuclear units on June 1, 2017 and June 1, 2018, respectively, as well as an increase of $ 60 million primarily due to an increase in the estimated costs to decommission the Oyster Creek nuclear unit as a result of the completion of an updated decommissioning cost study. Refer to Note 7 - Early Nuclear Plant Retirements for additional information regarding the announced early retirements of Clinton and Quad Cities. The increase in the ARO liability for Clinton and Quad Cities incorporates the early shutdown dates (including fleet-wide impacts of spent nuclear fuel removal and storage costs), increases in the assumed probabilities of longer term decommissioning scenarios, and reflects an increase in the estimated costs to decommission based on updated decommissioning cost studies reflecting the early retirement of these units. The financial statement impact related to the increase in the ARO liability due to the changes in, and timing of, estimated cash flows resulted in a corresponding increase in Property, plant and equipment on Exelon’s and Generation’s Consolidated Balance Sheets. The majority of the increase in cost will be amortized over the remaining useful lives of the Clinton, Quad Cities and Oyster Creek nuclear plants, which are set to retire in 2017, 2018 and 2019, respectively. Nuclear Decommissioning Trust Fund Investments At September 30, 2016 and December 31, 2015 , Exelon and Generation had NDT fund investments totaling $11,076 million and $10,342 million , respectively. The following table provides unrealized gains on NDT funds for the three and nine months ended September 30, 2016 and 2015 : Exelon and Generation Exelon and Generation Three Months Ended September 30, Nine Months Ended 2016 2015 2016 2015 Net unrealized gains (losses) on decommissioning trust funds — Regulatory Agreement Units (a) $ 155 $ (301 ) $ 286 $ (385 ) Net unrealized gains (losses) on decommissioning trust funds — Non-Regulatory Agreement Units (b)(c) 116 (218 ) 216 (274 ) _________ (a) Net unrealized gains related to Generation’s NDT funds associated with Regulatory Agreement Units are included in Regulatory liabilities on Exelon’s Consolidated Balance Sheets and Noncurrent payables to affiliates on Generation’s Consolidated Balance Sheets. (b) Excludes $(5) million of net unrealized gain related to the Zion Station pledged assets for the three months ended September 30, 2016 . Excludes $(2) million and $9 million of net unrealized gain related to the Zion Station pledged assets for the nine months ended September 30, 2016 and 2015 , respectively. Net unrealized gains related to Zion Station pledged assets are included in the Payable for Zion Station decommissioning on Exelon’s and Generation’s Consolidated Balance Sheets. (c) Net unrealized gains related to Generation’s NDT funds with Non-Regulatory Agreement Units are included within Other, net in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income. Interest and dividends on NDT fund investments are recognized when earned and are included in Other, net in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income. Interest and dividends earned on the NDT fund investments for the Regulatory Agreement Units are eliminated within Other, net in Exelon’s and Generation’s Consolidated Statement of Operations and Comprehensive Income. Refer to Note 3 — Regulatory Matters and Note 26 — Related Party Transactions of the Exelon 2015 Form 10-K for information regarding regulatory liabilities at ComEd and PECO and intercompany balances between Generation, ComEd and PECO reflecting the obligation to refund to customers any decommissioning-related assets in excess of the related decommissioning obligations. Zion Station Decommissioning On September 1, 2010, Generation completed an Asset Sale Agreement (ASA) with EnergySolutions Inc. and its wholly owned subsidiaries, EnergySolutions, LLC (EnergySolutions) and ZionSolutions, under which ZionSolutions has assumed responsibility for completing certain decommissioning activities at Zion Station, which is located in Zion, Illinois and ceased operation in 1998. See Note 16 — Asset Retirement Obligations of the Exelon 2015 Form 10-K for information regarding the specific treatment of assets, including NDT funds, and decommissioning liabilities transferred in the transaction. ZionSolutions is subject to certain restrictions on its ability to request reimbursements from the Zion Station NDT funds as defined within the ASA. Therefore, the transfer of the Zion Station assets did not qualify for asset sale accounting treatment and, as a result, the related NDT funds were reclassified to Pledged assets for Zion Station decommissioning within Generation’s and Exelon’s Consolidated Balance Sheets and will continue to be measured in the same manner as prior to the completion of the transaction. Additionally, the transferred ARO for decommissioning was replaced with a Payable for Zion Station decommissioning in Generation’s and Exelon’s Consolidated Balance Sheets. Changes in the value of the Zion Station NDT assets, net of applicable taxes, are recorded as a change in the Payable to ZionSolutions. At no point will the payable to ZionSolutions exceed the project budget of the costs remaining to decommission Zion Station. Generation has retained its obligation for the SNF. Following ZionSolutions’ completion of its contractual obligations and transfer of the NRC license to Generation, Generation will store the SNF at Zion Station until it is transferred to the DOE for ultimate disposal, and will complete all remaining decommissioning activities associated with the SNF dry storage facility. Generation has a liability of approximately $87 million which is included within the nuclear decommissioning ARO at September 30, 2016 . Generation also has retained NDT assets to fund its obligation to maintain the SNF at Zion Station until transfer to the DOE and to complete all remaining decommissioning activities for the SNF storage facility. Any shortage of funds necessary to maintain the SNF and decommission the SNF storage facility is ultimately required to be funded by Generation. Any Zion Station NDT funds remaining after the completion of all decommissioning activities will be returned to ComEd customers in accordance with the applicable orders. The following table provides the pledged assets and payables to ZionSolutions, and withdrawals by ZionSolutions at September 30, 2016 and December 31, 2015 : Exelon and Generation September 30, 2016 December 31, 2015 Carrying value of Zion Station pledged assets $ 135 $ 206 Payable to Zion Solutions (a) 124 189 Current portion of payable to Zion Solutions (b) 91 99 Cumulative withdrawals by Zion Solutions to pay decommissioning costs (c) 855 786 _________ (a) Excludes a liability recorded within Exelon’s and Generation’s Consolidated Balance Sheets related to the tax obligation on the unrealized activity associated with the Zion Station NDT funds. The NDT funds will be utilized to satisfy the tax obligations as gains and losses are realized. (b) Included in Other current liabilities within Exelon’s and Generation’s Consolidated Balance Sheets. (c) Includes project expenses to decommission Zion Station and estimated tax payments on Zion Station NDT fund earnings. NRC Minimum Funding Requirements NRC regulations require that licensees of nuclear generating facilities demonstrate reasonable assurance that funds will be available in specified minimum amounts to decommission the facility at the end of its life. Generation filed its biennial decommissioning funding status report with the NRC on March 31, 2015. This report reflects the status of decommissioning funding assurance as of December 31, 2014. Due to increased cost estimates received in the second half of 2014, Braidwood Units 1 and 2, and Byron Unit 2 did not meet the NRC's minimum funding assurance criteria as of December 31, 2014. NRC guidance provides licensees with two years or by the time of submitting the next biennial report (on or before March 31, 2017) to resolve funding assurance shortfalls. On February 4, 2016, Generation submitted to the NRC an updated decommissioning funding status report for Braidwood Units 1 and 2, and Byron Unit 2. This updated report reflected the recently approved license renewals for these units, and showed that the shortfall identified in the March 31, 2015 report has now been resolved and that Generation has provided adequate decommissioning funding assurance for each unit. On March 31, 2016, Generation submitted its NRC required annual decommissioning funding status report as of December 31, 2015 for reactors that have been shut down or are within five years of shut down except for Zion Station which is included in a separate report to the NRC submitted by EnergySolutions (see Zion Station Decommissioning above). As of December 31, 2015, Generation provided adequate decommissioning funding assurance for all of its reactors that have been shut down or are within five years of shut down except for Peach Bottom Unit 1. As a former PECO plant, financial assurance for decommissioning Peach Bottom Unit 1 is provided by the NDT fund in addition to collections from PECO ratepayers. As discussed in Note 16 - Asset Retirement Obligations of Exelon's 2015 Form 10-K, the amount collected from PECO ratepayers will be adjusted in the next filing to the PAPUC with new rates effective January 1, 2018. Generation will file its next decommissioning funding status report with the NRC by March 31, 2017. This report will reflect the status of decommissioning funding assurance as of December 31, 2016 and will reflect the impacts of the announced early retirements of Clinton and Quad Cities. A shortfall could require Exelon to post parental guarantees for Generation's share of the funding assurance. However, the amount of any required guarantees will ultimately depend on the decommissioning approach adopted at each site, the associated level of costs, and the decommissioning trust fund investment performance going forward.

Retirement Benefits (All Regist

Retirement Benefits (All Registrants)	9 Months Ended
	Sep. 30, 2016
Compensation and Retirement Disclosure [Abstract]
Retirement Benefits (Exelon, Generation, ComEd, PECO and BGE)	Retirement Benefits (All Registrants) Exelon sponsors defined benefit pension plans and other postretirement benefit plans for essentially all employees. Effective March 23, 2016 , Exelon became the sponsor of all of PHI's defined benefit pension and other postretirement benefit plans, and assumed PHI's benefit plan obligations and related assets. As a result, PHI's benefit plan net obligation and related regulatory assets were transferred to Exelon. The legacy PHI pension and other postretirement benefit plans were initially remeasured on February 29, 2016 as a result of the short time between the merger close and the end of the first quarter of 2016, using current assumptions, including the discount rate. Exelon updated these amounts in June 2016 to reflect assumptions at March 31, 2016. The updated valuation resulted in a $ 25 million reduction in the net obligation. Defined Benefit Pension and Other Postretirement Benefits During the first quarter of 2016 , Exelon received an updated valuation of its legacy pension and other postretirement benefit obligations to reflect actual census data as of January 1, 2016 . This valuation resulted in an increase to the pension obligation of $35 million and a decrease to the other postretirement benefit obligation of $8 million . Additionally, accumulated other comprehensive loss increased by approximately $2 million (after tax), regulatory assets increased by approximately $27 million , and regulatory liabilities increased by approximately $3 million . The majority of the 2016 pension benefit cost for legacy Exelon-sponsored plans is calculated using an expected long-term rate of return on plan assets of 7.00% and a discount rate of 4.29% . The majority of the 2016 other postretirement benefit cost is calculated using an expected long-term rate of return on plan assets of 6.71% for funded plans and a discount rate of 4.29% . The 2016 pension benefit costs for the legacy PHI plans are calculated using an expected long-term rate of return on plan assets of 6.50% and a discount rate of 3.96% for the majority of the pension plans. The 2016 other postretirement benefit cost is calculated using an expected long-term rate of return on plan assets of 6.75% and a discount rate of 3.80% . A portion of the net periodic benefit cost for all plans is capitalized within the Consolidated Balance Sheets. The following table presents the components of Exelon's net periodic benefit costs, prior to capitalization, for the three and nine months ended September 30, 2016 and 2015 . Pension Benefits Other Postretirement Benefits Components of net periodic benefit cost: 2016 2015 2016 2015 Service cost $ 92 $ 82 $ 27 $ 30 Interest cost 215 178 47 42 Expected return on assets (293 ) (257 ) (42 ) (38 ) Amortization of: Prior service cost (benefit) 3 3 (48 ) (43 ) Actuarial loss 142 142 18 20 Net periodic benefit cost $ 159 $ 148 $ 2 $ 11 Pension Benefits Other Postretirement Benefits 2016 (a) 2015 2016 (a) 2015 Components of net periodic benefit cost: Service cost $ 262 $ 245 $ 80 $ 89 Interest cost 616 533 138 125 Expected return on assets (847 ) (770 ) (121 ) (113 ) Amortization of: Prior service cost (benefit) 10 10 (138 ) (130 ) Actuarial loss 411 427 47 60 Net periodic benefit cost $ 452 $ 445 $ 6 $ 31 _______ (a) PHI net periodic benefit costs for the period prior to the merger are not included in the table above. Predecessor PHI Pension Benefits Other Postretirement Benefits Components of net periodic benefit cost: January 1, 2016 to March 23, 2016 Three Months Ended September 30, 2015 Nine Months Ended September 30, 2015 January 1, 2016 to March 23, 2016 Three Months Ended September 30, 2015 Nine Months Ended September 30, 2015 Service cost $ 12 $ 15 $ 43 $ 1 $ 2 $ 5 Interest cost 26 28 82 6 6 18 Expected return on assets (30 ) (35 ) (105 ) (5 ) (6 ) (17 ) Amortization of: Prior service cost (benefit) — — 1 (3 ) (3 ) (9 ) Actuarial loss 14 16 49 2 2 6 Net periodic benefit cost $ 22 $ 24 $ 70 $ 1 $ 1 $ 3 The amounts below represent Exelon's, Generation's, ComEd's, PECO's, BGE's, PHI's, Pepco's, DPL's, ACE's, BSC's and PHISCO's allocated portion of the pension and postretirement benefit plan costs, which were included in Property, plant and equipment within the respective Consolidated Balance Sheets and Operating and maintenance expense within the Consolidated Statement of Operations and Comprehensive Income during the three and nine months ended September 30, 2016 and 2015 . Three Months Ended September 30, Nine Months Ended September 30, Pension and Other Postretirement Benefit Costs 2016 2015 2016 2015 Exelon $ 161 $ 159 $ 458 $ 476 Generation 54 67 163 200 ComEd 41 52 124 155 PECO 8 10 25 29 BGE 17 16 51 49 BSC (a) 13 14 37 43 Pepco (b) 8 7 24 22 DPL (b) 4 3 13 11 ACE (b) 4 3 11 11 PHISCO (a)(b) 12 12 33 29 Successor Predecessor Successor Predecessor Pension and Other Postretirement Benefit Costs Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 March 24, 2016 to September 30, 2016 January 1, 2016 to March 23, 2016 Nine Months Ended September 30, 2015 PHI $ 28 $ 25 $ 58 $ 23 $ 73 _________ (a) These amounts primarily represent amounts billed to Exelon’s subsidiaries through intercompany allocations. These amounts are not included in the Generation, ComEd, PECO, BGE, PHI, Pepco, DPL or ACE amounts above. (b) Pepco's, DPL's, ACE's and PHISCO's pension and postretirement benefit costs for the nine months ended September 30, 2016 include $7 million , $4 million , $3 million and $9 million , respectively, of costs incurred prior to the closing of Exelon’s merger with PHI on March 23, 2016 . Defined Contribution Savings Plans The Registrants participate in various 401(k) defined contribution savings plans that are sponsored by Exelon. The plans are qualified under applicable sections of the IRC and allow employees to contribute a portion of their pre-tax and/or after-tax income in accordance with specified guidelines. All Registrants match a percentage of the employee contributions up to certain limits. The following table presents the matching contributions to the savings plans during the three and nine months ended September 30, 2016 and 2015 : Three Months Ended September 30, Nine Months Ended September 30, Savings Plan Matching Contributions 2016 2015 2016 2015 Exelon $ 51 $ 51 $ 107 $ 111 Generation 31 27 56 60 ComEd 10 10 23 23 PECO 3 3 7 7 BGE 2 5 5 10 BSC (a) 2 6 9 11 Pepco (b) — — 2 2 DPL (b) 1 1 2 2 ACE (b) — — 1 1 PHISCO (a)(b) 2 2 5 5 Successor Predecessor Successor Predecessor Savings Plan Matching Contributions Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 March 24, 2016 to September 30, 2016 January 1, 2016 to March 23, 2016 Nine Months Ended September 30, 2015 PHI $ 3 $ 3 $ 7 $ 3 $ 10 _________ (a) These amounts primarily represent amounts billed to Exelon and PHI's subsidiaries through intercompany allocations. These costs are not included in the Generation, ComEd, PECO, BGE, Pepco and DPL amounts above. (b) Pepco's, DPL's and PHISCO's matching contributions for the nine months ended September 30, 2016 include $1 million , $1 million ,and $1 million , respectively, of costs incurred prior to the closing of Exelon’s merger with PHI on March 23, 2016 , which is not included in Exelon’s matching contributions for the nine months ended September 30, 2016 .

Severance (All Registrants)

Severance (All Registrants)	9 Months Ended
	Sep. 30, 2016
Restructuring Charges [Abstract]
Severance (All Registrants)	Severance (All Registrants) The Registrants have an ongoing severance plan under which, in general, the longer an employee worked prior to termination the greater the amount of severance benefits. The Registrants record a liability and expense or regulatory asset for severance once terminations are probable of occurrence and the related severance benefits can be reasonably estimated. For severance benefits that are incremental to its ongoing severance plan (“one-time termination benefits”), the Registrants measure the obligation and record the expense at fair value at the communication date if there are no future service requirements, or, if future service is required to receive the termination benefit, ratably over the required service period. Ongoing Severance Plans The Registrants provide severance and health and welfare benefits under Exelon’s ongoing severance benefit plans to terminated employees in the normal course of business. These benefits are accrued for when the benefits are considered probable and can be reasonably estimated. For the three and nine months ended September 30, 2016 and 2015 , Exelon, Generation, ComEd and PHI recorded the following severance costs (benefits) associated with these ongoing severance benefits within Operating and maintenance expense in their Consolidated Statements of Operations and Comprehensive Income. Successor Exelon Generation (a) ComEd (a) PHI Three Months Ended September 30, 2016 $ 8 $ 7 $ — $ 1 September 30, 2015 (3 ) (3 ) — — Nine Months Ended September 30, 2016 $ 12 $ 10 $ 1 $ 1 September 30, 2015 18 17 1 — _______ (a) The amounts above for Generation include less than $1 million for amounts billed by BSC through intercompany allocations for both the three months ended September 30, 2016 and 2015 , and $2 million for both the nine months ended September 30, 2016 and 2015 . The amounts above for ComEd include $1 million billed by BSC through intercompany allocations for both the nine months ended September 30, 2016 and 2015 . The amounts above for PHI include $1 million billed by BSC through intercompany allocations for the three and nine months ended September 30, 2016 . Early Plant Retirement-Related Severance As a result of the Clinton and Quad Cities plant retirement decision, Exelon and Generation will incur certain employee-related costs, including severance benefit costs. Severance benefits will be provided to impacted union and non-union employees, to the extent that those employees are not redeployed to other locations. The final amount of severance cost will ultimately depend on the specific employees severed. For the three and nine months ended September 30, 2016 , the Registrants recorded the following severance costs (benefits) related to the early plant retirements within Operating and maintenance expense in their Consolidated Statements of Operations and Comprehensive Income, pursuant to the authoritative guidance for ongoing severance plans: Exelon Generation (a) Three Months Ended September 30, 2016 $ (2 ) $ (2 ) Nine Months Ended September 30, 2016 $ 44 $ 44 (a) The amounts above for Generation include $2 million for amounts billed by BSC through intercompany allocations for the nine months ended September 30, 2016 . Cost Management Program-Related Severance In August 2015, Exelon announced a cost management program focused on cost savings at BSC and Generation, including the elimination of approximately 500 positions. These actions are in response to the continuing economic challenges confronting all parts of Exelon’s business and industry, necessitating continued focus on cost management through enhanced efficiency and productivity. Exelon expects that approximately 250 corporate support positions in BSC and approximately 250 positions located throughout Generation will be eliminated. Upon Senior Management approval of the cost management targets and initiatives in the first quarter of 2016, Exelon recorded severance benefit costs of $17 million associated with the anticipated position reductions. Additional severance benefit costs recorded in the third quarter were $1 million for Generation and Exelon. The final amount of the charge will ultimately depend on the specific employees severed. For the nine months ended September 30, 2016 , the Registrants recorded the following severance costs related to the cost management program within Operating and maintenance expense in their Consolidated Statements of Operations and Comprehensive Income, pursuant to the authoritative guidance for ongoing severance plans: Exelon Generation ComEd PECO BGE Nine Months Ended September 30, 2016 Severance benefits (a) $ 18 $ 13 $ 3 $ 1 $ 1 _______ (a) The amounts above for Generation, ComEd, PECO and BGE include $7 million , $3 million , $1 million and $1 million , respectively, for amounts billed by BSC through intercompany allocations for the nine months ended September 30, 2016 . Severance Costs Related to the PHI Merger Upon closing the PHI Merger, Exelon recorded a severance accrual for the anticipated employee position reductions as a result of the post-merger integration. Cash payments under the plan began in May 2016 and will continue through 2020. For the three months ended September 30, 2016 , the PHI merger severance costs were immaterial. For the nine months ended September 30, 2016 , the Registrants recorded the following severance costs associated with the identified job reductions within Operating and maintenance expense in their Consolidated Statements of Operations and Comprehensive Income, pursuant to the authoritative guidance for ongoing severance plans: Successor Exelon Generation ComEd PECO BGE PHI Pepco (b) DPL (c) ACE Nine Months Ended September 30, 2016 Severance benefits (a) $ 55 $ 9 $ 2 $ 1 $ 1 $ 42 $ 20 $ 12 $ 10 ______________ (a) The amounts above for Generation, ComEd, PECO, BGE, Pepco, DPL and ACE include amounts billed by BSC and/or PHISCO through intercompany allocations of $8 million , $2 million , $1 million , $1 million , $19 million , $11 million and $10 million for the nine months ended September 30, 2016 . (b) Pepco established a regulatory asset of $10 million as of September 30, 2016 , primarily for severance benefit costs related to the PHI merger. (c) DPL established a regulatory asset of $3 million as of September 30, 2016 , primarily for severance benefit costs related to the PHI merger. Severance Liability Amounts included in the table below represent the severance liability recorded for the severance plans above for employees of each Registrant and exclude amounts included at Exelon and billed through intercompany allocations: Successor Severance Liability Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance at December 31, 2015 $ 35 $ 23 $ 3 $ — $ 1 $ — $ — $ — $ — Severance charges (a)(b) 136 63 1 — — 53 1 1 — Payments (39 ) (7 ) (1 ) — (1 ) (25 ) (1 ) (1 ) — Balance at September 30, 2016 $ 132 $ 79 $ 3 $ — $ — $ 28 $ — $ — $ — ______________ (a) Includes salary continuance and health and welfare severance benefits. Amounts primarily represent benefits provided for the PHI post-merger integration, the Clinton and Quad Cities early plant retirements and the cost management program. (b) Represents activity from March 24, 2016 to September 30, 2016 for PHI, Pepco, DPL and ACE.

Mezzanine Equity Mezzanine Equi

Mezzanine Equity Mezzanine Equity (Exelon, Generation and PHI)	9 Months Ended
	Sep. 30, 2016
Noncontrolling Interest [Abstract]
Noncontrolling Interest Disclosure (Exelon, Generation and PHI)	16 . Mezzanine Equity (Exelon, Generation and PHI) Contingently Redeemable Noncontrolling Interests (Exelon and Generation) In November 2015, 2015 ESA Investco, LLC, a wholly owned subsidiary of Generation, entered into an arrangement to sell a portion of its equity to a tax equity investor. Pursuant to the operating agreement, in certain circumstances the equity contributed by the noncontrolling interests holder could be contingently redeemable. These circumstances are outside of the control of Generation and the noncontrolling interests holder resulting in a portion of the noncontrolling interests being considered contingently redeemable and thus presented in mezzanine equity on the consolidated balance sheet. The following table summarizes the changes in the contingently redeemable noncontrolling interests for the nine months ended September 30, 2016 : Balance at December 31, 2015 $ 28 Cash received from noncontrolling interests 105 Release of contingency (107 ) Balance at September 30, 2016 $ 26 Preferred Stock (PHI) In connection with the PHI Merger Agreement, Exelon purchased 18,000 originally issued shares of PHI preferred stock for a purchase price of $ 180 million . PHI excluded the preferred stock from equity at December 31, 2015 since the preferred stock contained conditions for redemption that were not solely within the control of PHI. Management determined that the preferred stock contained embedded features requiring separate accounting consideration to reflect the potential value to PHI that any issued and outstanding preferred stock could be called and redeemed at a nominal par value upon a termination of the merger agreement under certain circumstances due to the failure to obtain required regulatory approvals. The embedded call and redemption features on the shares of the preferred stock in the event of such a termination were separately accounted for as derivatives. As of December 31, 2015, the fair value of the derivative related to the preferred stock was estimated to be $ 18 million based on PHI’s updated assessment and was included in Current assets with a corresponding increase in Preferred stock on PHI's Consolidated Balance Sheets. Immediately prior to the merger date, PHI updated its assessment of the fair value of the derivative and reduced the fair value to zero , recording the $ 18 million decrease in fair value as a reduction of Other, within PHI's predecessor period, January 1, 2016 to March 23, 2016 , Consolidated Statements of Operations and Comprehensive Income. On March 23, 2016 , the preferred stock was cancelled and the $ 180 million cash consideration previously received by PHI to issue the preferred stock was treated as additional merger purchase price consideration.

Changes in Accumulated Other Co

Changes in Accumulated Other Comprehensive Income (Exelon, Generation, PECO and PHI)	9 Months Ended
	Sep. 30, 2016
Changes in Accumulated Other Comprehensive Income [Abstract]
Comprehensive Income (Loss) Note [Text Block]	Changes in Accumulated Other Comprehensive Income (Exelon, Generation, PECO and PHI) The following tables present changes in accumulated other comprehensive income (loss) (AOCI) by component for the nine months ended September 30, 2016 and 2015 : Nine Months Ended September 30, 2016 Gains and (losses) on Cash Flow Hedges Unrealized Gains and (losses) on Marketable Securities Pension and Non-Pension Postretirement Benefit Plan Items Foreign Currency Items AOCI of Equity Investments Total Exelon (a) Beginning balance $ (19 ) $ 3 $ (2,565 ) $ (40 ) $ (3 ) $ (2,624 ) OCI before reclassifications (1 ) — (2 ) 3 (5 ) (5 ) Amounts reclassified from AOCI (b) (3 ) — 104 5 — 106 Net current-period OCI (4 ) — 102 8 (5 ) 101 Ending balance $ (23 ) $ 3 $ (2,463 ) $ (32 ) $ (8 ) $ (2,523 ) Generation (a) Beginning balance $ (21 ) $ 1 $ — $ (40 ) $ (3 ) $ (63 ) OCI before reclassifications — 1 — 3 1 5 Amounts reclassified from AOCI (b) (3 ) — — 5 — 2 Net current-period OCI (3 ) 1 — 8 1 7 Ending balance $ (24 ) $ 2 $ — $ (32 ) $ (2 ) $ (56 ) PECO (a) Beginning balance $ — $ 1 $ — $ — $ — $ 1 OCI before reclassifications — — — — — — Amounts reclassified from AOCI (b) — — — — — — Net current-period OCI — — — — — — Ending balance $ — $ 1 $ — $ — $ — $ 1 PHI Predecessor (a) Beginning balance January 1, 2016 $ (8 ) $ — $ (28 ) $ — $ — $ (36 ) OCI before reclassifications — — — — — — Amounts reclassified from AOCI (b) — — 1 — — 1 Net current-period OCI — — 1 — — 1 Ending balance March 23, 2016 (c) $ (8 ) $ — $ (27 ) $ — $ — $ (35 ) Nine Months Ended September 30, 2015 Gains and (losses) on Hedging Activity Unrealized Gains and (losses) on Marketable Securities Pension and Non-Pension Postretirement Benefit Plan Items Foreign Currency Items AOCI of Equity Investments Total Exelon (a) Beginning balance $ (28 ) $ 3 $ (2,640 ) $ (19 ) $ — $ (2,684 ) OCI before reclassifications (18 ) — (29 ) (17 ) — (64 ) Amounts reclassified from AOCI (b) 22 — 130 — — 152 Net current-period OCI 4 — 101 (17 ) — 88 Ending balance $ (24 ) $ 3 $ (2,539 ) $ (36 ) $ — $ (2,596 ) Generation (a) Beginning balance $ (18 ) $ 1 $ — $ (19 ) $ — $ (36 ) OCI before reclassifications (13 ) — — (17 ) — (30 ) Amounts reclassified from AOCI (b) 6 — — — — 6 Net current-period OCI (7 ) — — (17 ) — (24 ) Ending balance $ (25 ) $ 1 $ — $ (36 ) $ — $ (60 ) PECO (a) Beginning balance $ — $ 1 $ — $ — $ — $ 1 OCI before reclassifications — — — — — — Amounts reclassified from AOCI (b) — — — — — — Net current-period OCI — — — — — — Ending balance $ — $ 1 $ — $ — $ — $ 1 PHI Predecessor (a) Beginning balance $ (9 ) $ — $ (37 ) $ — $ — $ (46 ) OCI before reclassifications — — — — — — Amounts reclassified from AOCI (b) 1 — 4 — — 5 Net current-period OCI 1 — 4 — — 5 Ending balance $ (8 ) $ — $ (33 ) $ — $ — $ (41 ) ________ (a) All amounts are net of tax and noncontrolling interest. Amounts in parenthesis represent a decrease in AOCI. (b) See next tables for details about these reclassifications. (c) As a result of the PHI Merger, the PHI predecessor balances at March 23, 2016 were reduced to zero on March 24, 2016 due to purchase accounting adjustments applied to PHI. ComEd, PECO, BGE, Pepco, DPL and ACE did not have any reclassifications out of AOCI to Net income during the three and nine months ended September 30, 2016 and 2015 . The following tables present amounts reclassified out of AOCI to Net income for Exelon, Generation and PHI during the three and nine months ended September 30, 2016 and 2015 . Three Months Ended September 30, 2016 Details about AOCI components Items reclassified out of AOCI (a) Affected line item in the Statement of Operations and Comprehensive Income Exelon Generation Amortization of pension and other postretirement benefit plan items Prior service costs (b) $ 19 $ — Actuarial losses (b) (76 ) — Total before tax (57 ) — Tax benefit 22 — Net of tax $ (35 ) $ — Gains (losses) on foreign currency translation Other $ (5 ) $ (5 ) Other income and (deductions) Total before tax (5 ) (5 ) Tax expense — — Net of tax $ (5 ) $ (5 ) Total Reclassifications for the period $ (40 ) $ (5 ) Comprehensive income Nine Months Ended September 30, 2016 Details about AOCI components Items reclassified out of AOCI (a) Affected line item in the Statement of Operations and Comprehensive Income Predecessor January 1, 2016 to March 23, 2016 Exelon Generation PHI Gains and (losses) on cash flow hedges Other cash flow hedges $ 5 $ 5 $ — Interest expense Total before tax 5 5 — Tax expense (2 ) (2 ) — Net of tax $ 3 $ 3 $ — Comprehensive income Amortization of pension and other postretirement benefit plan items Prior service costs (b) $ 57 $ — $ — Actuarial losses (b) (227 ) — (1 ) Total before tax (170 ) — (1 ) Tax benefit 66 — — Net of tax $ (104 ) $ — $ (1 ) Gains (losses) on foreign currency translation Other $ (5 ) $ (5 ) $ — Other income and (deductions) Total before tax (5 ) (5 ) — Tax expense — — — Net of tax $ (5 ) $ (5 ) $ — Total Reclassifications $ (106 ) $ (2 ) $ (1 ) Comprehensive income Three Months Ended September 30, 2015 Details about AOCI components Items reclassified out of AOCI (a) Affected line item in the Statement of Operations and Comprehensive Income Predecessor Exelon Generation PHI Gains and (losses) on cash flow hedges Other cash flow hedges $ (4 ) $ (4 ) $ (1 ) Interest expense Total before tax (4 ) (4 ) (1 ) Tax expense 1 1 — Net of tax $ (3 ) $ (3 ) $ (1 ) Comprehensive income Amortization of pension and other postretirement benefit plan items Prior service costs (b) $ 19 $ — $ — Actuarial losses (b) (90 ) — (2 ) Total before tax (71 ) — (2 ) Tax expense 28 — 2 Net of tax $ (43 ) $ — $ — Total Reclassifications for the period $ (46 ) $ (3 ) $ (1 ) Comprehensive income Nine Months Ended September 30, 2015 Details about AOCI components Items reclassified out of AOCI (a) Affected line item in the Statement of Operations and Comprehensive Income Predecessor Exelon Generation PHI Gains and (losses) on cash flow hedges Terminated interest rate swaps $ (26 ) $ — $ — Other, net Energy related hedges 2 2 — Operating revenues Other cash flow hedges (11 ) (11 ) (1 ) Interest expense Total before tax (35 ) (9 ) (1 ) Tax benefit 13 3 — Net of tax $ (22 ) $ (6 ) $ (1 ) Comprehensive income Amortization of pension and other postretirement benefit plan items Prior service costs (b) $ 57 $ — $ — Actuarial losses (b) (270 ) — (7 ) Total before tax (213 ) — (7 ) Tax benefit 83 — 3 Net of tax $ (130 ) $ — $ (4 ) Total Reclassifications $ (152 ) $ (6 ) $ (5 ) Comprehensive income _______ (a) Amounts in parenthesis represent a decrease in net income. (b) This AOCI component is included in the computation of net periodic pension and OPEB cost (see Note 13 — Retirement Benefits for additional details). The following table presents income tax expense (benefit) allocated to each component of other comprehensive income (loss) during the three and nine months ended September 30, 2016 and 2015 : Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 Exelon Pension and non-pension postretirement benefit plans: Prior service benefit reclassified to periodic benefit cost $ 7 $ 8 $ 22 $ 22 Actuarial loss reclassified to periodic cost (29 ) (35 ) (88 ) (105 ) Pension and non-pension postretirement benefit plans valuation adjustment 1 — 1 17 Change in unrealized gain/(loss) on cash flow hedges (1 ) 3 3 (3 ) Change in unrealized loss on equity investments — — 3 — Change in unrealized gain on marketable securities (1 ) — (1 ) — Total $ (23 ) $ (24 ) $ (60 ) $ (69 ) Generation Change in unrealized gain/(loss) on cash flow hedges $ (2 ) $ 3 $ 1 $ 4 Change in unrealized loss on equity investments — — 3 — Change in unrealized gain on marketable securities — — — — Total $ (2 ) $ 3 $ 4 $ 4 Predecessor PHI Three Months Ended January 1, 2016 to March 23, 2016 Nine Months Ended September 30, 2015 Pension and non-pension postretirement benefit plans: Actuarial loss reclassified to periodic cost $ (2 ) $ — $ (3 )

Earnings Per Share and Equity (

Earnings Per Share and Equity (Exelon)	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Earnings Per Share and Equity (Exelon)	Earnings Per Share and Equity (Exelon and BGE) Earnings per Share (Exelon) Diluted earnings per share is calculated by dividing Net income attributable to common shareholders by the weighted average number of shares of common stock outstanding, including shares to be issued upon exercise of stock options, performance share awards and restricted stock outstanding under Exelon’s LTIPs considered to be common stock equivalents. The following table sets forth the components of basic and diluted earnings per share and shows the effect of these stock options, performance share awards and restricted stock on the weighted average number of shares outstanding used in calculating diluted earnings per share: Three Months Ended September 30, Nine Months Ended September 30, Exelon 2016 2015 2016 2015 Net income attributable to common shareholders $ 490 $ 629 $ 930 $ 1,959 Weighted average common shares outstanding — basic 925 913 924 879 Assumed exercise and/or distributions of stock-based awards 2 2 2 4 Weighted average common shares outstanding — diluted 927 915 926 883 The number of stock options not included in the calculation of diluted common shares outstanding due to their antidilutive effect was approximately 11 million and 12 million for the three and nine months ended September 30, 2016 , respectively and 14 million for three and nine months ended September 30, 2015 . The number of equity units related to the PHI Merger not included in the calculation of diluted common shares outstanding due to their antidilutive effect was less than 1 million for the three and nine months ended September 30, 2016 , respectively, and 4 million and 2 million for the three and nine months ended September 30, 2015 , respectively. Refer to Note 19 — Shareholder's Equity of the Exelon 2015 Form 10-K for further information regarding the equity units. Under share repurchase programs, 35 million shares of common stock are held as treasury stock with a cost of $2.3 billion as of September 30, 2016 . In 2008, Exelon management decided to defer indefinitely any share repurchases. Preference Stock Redemption (BGE) BGE had $190 million of cumulative preference stock that was redeemable at its option at any time after October 1, 2015 for the redemption price of $100 per share, plus accrued and unpaid dividends. On July 3, 2016, BGE redeemed all 400,000 shares of its outstanding 7.125% Cumulative Preference Stock, 1993 Series and all 600,000 shares of its outstanding 6.99% Cumulative Preference Stock, 1995 Series for $100 million , plus accrued and unpaid dividends. On September 18, 2016, BGE redeemed the remaining 500,000 shares of its outstanding 6.970% Cumulative Preference Stock, 1993 Series and the remaining 400,000 shares of its outstanding 6.70% Cumulative Preference Stock, 1993 Series for $90 million , plus accrued and unpaid dividends.

Commitments and Contingencies (

Commitments and Contingencies (All Registrants)	9 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies (All Registrants)	18 . Commitments and Contingencies ( All Registrants ) The following is an update to the current status of commitments and contingencies set forth in Note 23 of the Exelon 2015 Form 10-K and Note 16 of the PHI 2015 Form 10-K. See Note 4 - Mergers, Acquisitions and Dispositions for further discussion on the PHI Merger commitments. Commitments Constellation Merger Commitments (Exelon and Generation) In February 2012, the MDPSC issued an Order approving the Exelon and Constellation merger. As part of the MDPSC Order, Exelon agreed to provide a package of benefits to BGE customers, the City of Baltimore and the State of Maryland, resulting in an estimated direct investment in the State of Maryland of approximately $1 billion . The direct investment estimate includes $95 million to $120 million relating to the construction of a headquarters building in Baltimore for Generation’s competitive energy businesses. The direct investment commitment also includes $450 million to $550 million relating to Exelon and Generation’s development or assistance in the development of 275 — 300 MWs of new generation in Maryland, which is expected to be completed over a period of 10 years. As of September 30, 2016 , Exelon and Generation have incurred $ 404 million towards satisfying the commitment for new generation development in the state of Maryland, with approximately 220 MW of the new generation commencing with commercial operations to date. The MDPSC Order contemplates various options for complying with the new generation development commitments, including building or acquiring generating assets, making subsidy or compliance payments, or in circumstances in which the generation build is delayed or certain specified provisions are elected, making liquidated damages payments. Exelon and Generation expect that the majority of these commitments will be satisfied by building or acquiring generating assets and, therefore, will be primarily capital in nature and recognized as incurred. However, during the third quarter of 2014, the conditions associated with one of the generation development commitments changed such that Exelon and Generation believe that the most likely outcome will involve making subsidy payments and/or liquidated damages payments rather than constructing the specified generating plant. As a result, Exelon and Generation recorded a pre-tax $44 million loss contingency related to this generation development commitment. While this $44 million loss contingency represents Generation's best estimate of the future obligation, it is reasonably possible that Exelon and Generation could ultimately be required to make cumulative subsidy payments of up to a maximum of approximately $105 million over a 20 -year period dependent on actual generating output from a successfully constructed generating plant. Equity Investment Commitments (Exelon and Generation) Generation has entered into equity purchase agreements that include commitments to invest additional equity through incremental payments to fund the anticipated needs of the planned operations of the associated companies. The commitments include approximately $20 million of in-kind services and 100% of 2015 ESA Investco, LLC's equity commitment since 2015 ESA Investco, LLC is consolidated by Generation (see Note 3 - Variable Interest Entities for additional details). As of September 30, 2016 , Generation’s estimated commitments relating to its equity purchase agreements, including the in-kind services contributions, is anticipated to be as follows: Total 2016 (a) $ 79 2017 25 2018 4 Total $ 108 ________ (a) The noncontrolling interests holder of 2015 ESA Investco, LLC will contribute up to $31 million in support of a portion of the remaining equity commitment. Commercial Commitments (All Registrants) The Registrants’ commercial commitments as of September 30, 2016 , representing commitments potentially triggered by future events were as follows: Successor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Letters of credit (non-debt) (a) $ 1,720 $ 1,650 $ 16 $ 23 $ 2 $ 1 $ — $ — $ 1 Surety bonds (b) 1,084 984 10 9 11 16 9 4 3 Financing trust guarantees 628 — 200 178 250 — — — — Nuclear insurance premiums (c) 3,045 3,045 — — — — — — — Guaranteed lease residual values (d) 20 — — — — 20 6 7 5 Total commercial commitments $ 6,497 $ 5,679 $ 226 $ 210 $ 263 $ 37 $ 15 $ 11 $ 9 ________ (a) Letters of credit (non-debt) - Exelon and certain subsidiaries maintain non-debt letters of credit to provide credit support for certain transactions as requested by third parties. (b) Surety bonds—Guarantees issued related to contract and commercial agreements, excluding bid bonds. (c) Nuclear insurance premiums — Represents the maximum amount that Generation would be required to pay for retrospective premiums in the event of nuclear disaster at any domestic site, including CENG sites, under the Secondary Financial Protection pool as required under the Price-Anderson Act as well as the current aggregate annual retrospective premium obligation that could be imposed by NEIL. See the Nuclear Insurance section within this note for additional details on Generation’s nuclear insurance premiums. (d) Represents the maximum potential obligation in the event that the fair value of certain leased equipment and fleet vehicles is zero at the end of the maximum lease term. The maximum lease term associated with these assets ranges from 3 to 8 years. The maximum potential obligation at the end of the minimum lease term would be $50 million , $13 million of which is a guarantee by Pepco, $17 million by DPL and $13 million by ACE. The minimum lease term associated with these assets ranges from 1 to 4 years. Historically, payments under the guarantees have not been made and PHI believes the likelihood of payments being required under the guarantees is remote. Nuclear Insurance (Exelon and Generation) Generation is subject to liability, property damage and other risks associated with major incidents at any of its nuclear stations, including the CENG nuclear stations. Generation has mitigated its financial exposure to these risks through insurance and other industry risk-sharing provisions. The Price-Anderson Act was enacted to ensure the availability of funds for public liability claims arising from an incident at any of the U.S. licensed nuclear facilities and also to limit the liability of nuclear reactor owners for such claims from any single incident. As of September 30, 2016 , the current liability limit per incident is $13.4 billion and is subject to change to account for the effects of inflation and changes in the number of licensed reactors. An inflation adjustment must be made at least once every 5 years and the last inflation adjustment was made effective September 10, 2013. In accordance with the Price-Anderson Act, Generation maintains financial protection at levels equal to the amount of liability insurance available from private sources through the purchase of private nuclear energy liability insurance for public liability claims that could arise in the event of an incident. As of September 30, 2016 , the amount of nuclear energy liability insurance purchased is $375 million for each operating site. Additionally, the Price-Anderson Act requires a second layer of protection through the mandatory participation in a retrospective rating plan for power reactors (currently 102 reactors) resulting in an additional $13.0 billion in funds available for public liability claims. Participation in this secondary financial protection pool requires the operator of each reactor to fund its proportionate share of costs for any single incident that exceeds the primary layer of financial protection. Under the Price-Anderson Act, the maximum assessment in the event of an incident for each nuclear operator, per reactor, per incident (including a 5% surcharge), is $127.3 million , payable at no more than $19 million per reactor per incident per year. Exelon’s maximum liability per incident is approximately $2.7 billion , including CENG's related liability. In addition, the U.S. Congress could impose revenue-raising measures on the nuclear industry to pay public liability claims exceeding the $13.4 billion limit for a single incident. As part of the execution of the NOSA on April 1, 2014, Generation executed an Indemnity Agreement pursuant to which Generation agreed to indemnify EDF and its affiliates against third-party claims that may arise from any future nuclear incident (as defined in the Price-Anderson Act) in connection with the CENG nuclear plants or their operations. Exelon guarantees Generation’s obligations under this indemnity. See Note 5 — Investment in Constellation Energy Nuclear Group, LLC of the Exelon 2015 Form 10-K for additional information on Generation’s operations relating to CENG. Generation is required each year to report to the NRC the current levels and sources of property insurance that demonstrates Generation possesses sufficient financial resources to stabilize and decontaminate a reactor and reactor station site in the event of an accident. The property insurance maintained for each facility is currently provided through insurance policies purchased from NEIL, an industry mutual insurance company of which Generation is a member. NEIL provides “all risk” property damage, decontamination and premature decommissioning insurance for each station for losses resulting from damage to its nuclear plants, either due to accidents or acts of terrorism. If the decision is made to decommission the facility, a portion of the insurance proceeds will be allocated to a fund, which Generation is required by the NRC to maintain, to provide for decommissioning the facility. In the event of an insured loss, Generation is unable to predict the timing of the availability of insurance proceeds to Generation and the amount of such proceeds that would be available. In the event that one or more acts of terrorism cause accidental property damage within a twelve-month period from the first accidental property damage under one or more policies for all insured plants, the maximum recovery for all losses by all insureds will be an aggregate of $3.2 billion plus such additional amounts as the insurer may recover for all such losses from reinsurance, indemnity and any other source, applicable to such losses. For its insured losses, Generation is self-insured to the extent that losses are within the policy deductible or exceed the amount of insurance maintained. Uninsured losses and other expenses, to the extent not recoverable from insurers or the nuclear industry, could also be borne by Generation. Any such losses could have a material adverse effect on Exelon’s and Generation’s financial condition, results of operations and liquidity. Environmental Issues (All Registrants) General. The Registrants’ operations have in the past, and may in the future, require substantial expenditures in order to comply with environmental laws. Additionally, under Federal and state environmental laws, the Registrants are generally liable for the costs of remediating environmental contamination of property now or formerly owned by them and of property contaminated by hazardous substances generated by them. The Registrants own or lease a number of real estate parcels, including parcels on which their operations or the operations of others may have resulted in contamination by substances that are considered hazardous under environmental laws. In addition, the Registrants are currently involved in a number of proceedings relating to sites where hazardous substances have been deposited and may be subject to additional proceedings in the future. ComEd, PECO, BGE and DPL have identified sites where former MGP activities have or may have resulted in actual site contamination. For almost all of these sites, there are additional PRPs that may share responsibility for the ultimate remediation of each location. • ComEd has identified 42 sites, 17 of which the remediation has been completed and approved by the Illinois EPA or the U.S. EPA and 25 that are currently under some degree of active study and/or remediation. ComEd expects the majority of the remediation at these sites to continue through at least 2021. • PECO has identified 26 sites, 16 of which have been remediated in accordance with applicable PA DEP regulatory requirements. The remaining 10 sites are currently under some degree of active study and/or remediation. PECO expects the majority of the remediation at these sites to continue through at least 2022. • BGE has identified 13 former gas manufacturing or purification sites that it currently owns or owned at one time through a predecessor’s acquisition. Two gas manufacturing sites require some level of remediation and ongoing monitoring under the direction of the MDE. The required costs at these two sites are not considered material. One former gas purification site is currently under investigation at the direction of the MDE. For more information, see the discussion of the Riverside site below. • DPL has identified 2 sites, all of which the remediation has been completed and approved by the MDE or the Delaware Department of Natural Resources and Environmental Control. ComEd, pursuant to an ICC order, and PECO, pursuant to settlements of natural gas distribution rate cases with the PAPUC, are currently recovering environmental remediation costs of former MGP facility sites through customer rates. ComEd and PECO have recorded regulatory assets for the recovery of these costs. See Note 5 — Regulatory Matters for additional information regarding the associated regulatory assets. BGE is authorized to recover, and is currently recovering, environmental costs for the remediation of the former MGP facility sites from customers; however, while BGE does not have a rider for MGP clean-up costs, BGE has historically received recovery of actual clean-up costs in distribution rates. DPL has historically received recovery of actual clean-up costs in distribution rates. As of September 30, 2016 and December 31, 2015 , the Registrants had accrued the following undiscounted amounts for environmental liabilities in Other current liabilities and Other deferred credits and other liabilities within their respective Consolidated Balance Sheets: September 30, 2016 Total Environmental Investigation and Remediation Reserve Portion of Total Related to MGP Investigation and Remediation (a) Exelon $ 427 $ 318 Generation 76 — ComEd 283 281 PECO 36 34 BGE 2 2 PHI (Successor) 30 1 Pepco 27 — DPL 2 1 ACE 1 — December 31, 2015 Total Environmental Investigation and Remediation Reserve Portion of Total Related to MGP Investigation and Remediation (a) Exelon $ 369 $ 301 Generation 63 — ComEd 266 264 PECO 37 35 BGE 3 2 PHI (Predecessor) 33 1 Pepco 24 — DPL 3 1 ACE 1 — _____________________________ (a) For BGE, includes reserve for Riverside, a gas purification site. See discussion below for additional information. The historical nature of the MGP sites and the fact that many of the sites have been buried and built over, impacts the ability to determine a precise estimate of the ultimate costs prior to initial sampling and determination of the exact scope and method of remedial activity. Management determines its best estimate of remediation costs using all available information at the time of each study, including probabilistic and deterministic modeling for ComEd and PECO, and the remediation standards currently required by the applicable state environmental agency. Prior to completion of any significant clean up, each site remediation plan is approved by the appropriate state environmental agency. During the third quarter of 2016, ComEd and PECO completed an annual study of their future estimated MGP remediation requirements. The results of the study resulted in a $ 7 million and $2 million increase to environmental liabilities and related regulatory assets for ComEd and PECO, respectively. The Registrants cannot reasonably estimate whether they will incur other significant liabilities for additional investigation and remediation costs at these or additional sites identified by the Registrants, environmental agencies or others, or whether such costs will be recoverable from third parties, including customers. Water Quality Groundwater Contamination. In October 2007, a subsidiary of Constellation entered into a consent decree with the MDE relating to groundwater contamination at a third-party facility that was licensed to accept fly ash, a byproduct generated by coal-fired plants. The consent decree required the payment of a $1 million penalty, remediation of groundwater contamination resulting from the ash placement operations at the site, replacement of drinking water supplies in the vicinity of the site, and monitoring of groundwater conditions. Generation's remaining groundwater contamination reserve was approximately $13 million at September 30, 2016 and $ 12 million at December 31, 2015 . Benning Road Site NPDES Permit Limit Exceedances . Pepco holds an NPDES permit issued by EPA with a July 19, 2009 effective date, which authorizes discharges from the Benning Road site, including the Pepco Energy Services generating facility previously located on the site that was deactivated in 2012 and subsequently demolished. The 2009 permit for the first time imposed numerical limits on the allowable concentration of certain metals in storm water discharged from the site into the Anacostia River as determined by EPA to be necessary to meet the applicable District of Columbia surface water quality standards. The permit contemplated that Pepco would meet these limits over time through the use of best management practices (BMPs). As of December 2012, Pepco completed the implementation of the first two phases of BMPs identified in a plan approved by EPA (consisting principally of installing metal absorbing filters to capture contaminants at storm water inlets, removing stored equipment from areas exposed to the weather, covering and painting exposed metal pipes, and covering and cleaning dumpsters). These measures were effective in reducing metal concentrations in storm water discharges, but were not sufficient to meet all of the numerical limits for metals. Most of the quarterly monitoring results since the issuance of the permit have shown exceedances of the limits for copper and zinc, as well as occasional exceedances for iron and lead. The NPDES permit was due to expire on June 19, 2014. Pepco submitted a permit renewal application on December 17, 2013. In November 2014, EPA advised Pepco that it will not renew the permit until the Benning Road site has come into compliance with the existing permit limits. The current permit remains in effect pending EPA’s action on the renewal application. In December 2014, Pepco submitted a plan to EPA to implement the third phase of BMPs recommended in the original permit compliance plan with the objective of achieving full compliance with the permit limits for metals by the end of 2015 and Pepco immediately began to implement the additional BMPs in accordance with the plan. On September 1, 2015, Pepco submitted a report to EPA on the status of implementation of the third phase of BMPs. As of that date, Pepco had fully implemented most of the elements of the Phase 3 plan, including installation of upgraded storm water inlet controls (filters and booms), enhanced inspection and maintenance of inlets, removal of materials and equipment from exposure to storm water, and removal of accumulated sediments from the underground storm drains. The sampling results from the third quarter of 2015 showed compliance with all of the permit limits. However, more recent sampling results continued to show modest exceedances for copper and zinc. As confirmed by this latest sampling, because the permit limits are low and site conditions are subject to variation, Pepco has concluded that some form of storm water treatment prior to discharge will be necessary to ensure ongoing compliance with all permit limits and has begun the process of evaluating treatment options. The nature and scope of the necessary treatment system, and the amount of the associated capital expenditures, will not be known until Pepco has completed the evaluation and design process. Pepco has been engaged in discussions with representatives from EPA and the DOJ regarding permit compliance. On October 30, 2015, EPA filed a Clean Water Act civil enforcement action against Pepco in federal district court. Pepco expects that this enforcement action will be resolved through a consent decree that will (i) establish further requirements to achieve compliance with the permit limits, including the design and installation of an appropriate storm water treatment system as noted above, and (ii) include civil penalties for past noncompliance. Pepco has established what it believes is an appropriate reserve for potential penalties which is included in the table above. Pepco does not expect the amount of such penalties above the financial reserve to have a material adverse effect on Exelon’s, PHI’s and Pepco’s consolidated financial condition, results of operations or cash flows. Pepco and EPA are currently in discussions regarding the terms of the contemplated consent decree, and it is anticipated that the parties will finalize the consent decree before the end of 2016. In response to a joint motion by the parties, the court has extended the deadline for Pepco to answer the complaint to November 15, 2016, to give the parties time to work towards agreement on the terms of a consent decree. The parties contemplate seeking a further extension if necessary to complete their negotiations. Once executed by the parties, the consent decree will be filed with the court for review and approval following a period for public comment. On March 14, 2016, the court granted a motion by the Anacostia Riverkeeper to intervene in this case as a plaintiff along with EPA. As an intervenor, the Anacostia Riverkeeper will be entitled to file a brief commenting on the proposed consent decree and to appeal any decision by the court to approve the consent decree over the Anacostia Riverkeeper’s objection, but its participation is not expected to materially affect the progress or outcome of the consent decree negotiations. Solid and Hazardous Waste Cotter Corporation. The EPA has advised Cotter Corporation (Cotter), a former ComEd subsidiary, that it is potentially liable in connection with radiological contamination at a site known as the West Lake Landfill in Missouri. On February 18, 2000, ComEd sold Cotter to an unaffiliated third-party. As part of the sale, ComEd agreed to indemnify Cotter for any liability arising in connection with the West Lake Landfill. In connection with Exelon’s 2001 corporate restructuring, this responsibility to indemnify Cotter was transferred to Generation. On May 29, 2008, the EPA issued a Record of Decision approving the remediation option submitted by Cotter and the two other PRPs that required additional landfill cover. The current estimated cost of the landfill cover remediation for the site is approximately $90 million , which will be allocated among all PRPs. Generation has accrued what it believes to be an adequate amount to cover its anticipated share of such liability. By letter dated January 11, 2010, the EPA requested that the PRPs perform a supplemental feasibility study for a remediation alternative that would involve complete excavation of the radiological contamination. On September 30, 2011, the PRPs submitted the supplemental feasibility study to the EPA for review. Since June 2012, the EPA has requested that the PRPs perform a series of additional analyses and groundwater and soil sampling as part of the supplemental feasibility study, that are now scheduled to be completed in the fall of 2016 to enable the EPA to propose a remedy for public comment by the end of 2016. While the EPA has not yet formally announced a change in the schedule, the PRPs believe that the final supplemental feasibility study will not be completed until year-end 2016 and the EPA announcement of the proposed remedy will take place in the third quarter of 2017. Thereafter, the EPA will select a final remedy and enter into a Consent Decree with the PRPs to effectuate the remedy. Recent investigation has identified a number of other parties who may be PRPs and could be liable to contribute to the final remedy. Further investigation is underway. Generation believes that a partial excavation remedy is reasonably possible, but does not currently have a basis to establish a reasonable estimate of the range of costs. Generation believes the likelihood that the EPA would require a complete excavation remedy is remote . The cost of a partial or complete excavation could have a material, unfavorable impact on Generation’s and Exelon’s future results of operations and cash flows. During December 2015, the EPA took two actions related to the West Lake Landfill designed to abate what it termed as imminent and dangerous conditions at the landfill. The first involved installation by the PRPs of a non-combustible surface cover to protect against surface fires in areas where radiological materials are believed to have been disposed. Generation has accrued what it believes to be an adequate amount to cover its anticipated liability for this interim action. The second action involved EPA's public statement that it will require the PRPs to construct a barrier wall in an adjacent landfill to prevent a subsurface fire from spreading to those areas of the West Lake Landfill where radiological materials are believed to have been disposed. At this time, EPA has not provided sufficient details related to the basis for and the requirements and design of a barrier wall to enable Generation to determine the likelihood such a remedy will ultimately be implemented, assess the degree to which Generation may have liability as a potentially responsible party, or develop a reasonable estimate of the potential incremental costs. It is reasonably possible, however, that resolution of this matter could have a material, unfavorable impact on Generation's and Exelon's future results of operations and cash flows. Finally, one of the other PRP's, the landfill owner and operator of the adjacent landfill, has indicated that it will be making a contribution claim against Cotter for costs that it has incurred to prevent the subsurface fire from spreading to those areas of the West Lake Landfill where radiological materials are believed to have been disposed. At this time, Generation and Exelon do not possess sufficient information to assess this claim and are therefore unable to determine the impact on their future results of operations and cash flows. On February 2, 2016, the U.S. Senate passed a bill to transfer remediation authority over the West Lake Landfill from the EPA to the U.S. Army Corps of Engineers, under the Formerly Utilized Sites Remedial Action Program (FUSRAP). Such legislation would become final upon passage in the U.S. House of Representatives and the signature of the President, and be subject to annual funding appropriations in the U.S. Budget. Remediation under FUSRAP would not alter the liability of the PRPs, but could delay the determination of a final remedy and its implementation. On A ugust 8, 2011, Cotter was notified by the DOJ that Cotter is considered a PRP with respect to the government’s clean-up costs for contamination attributable to low level radioactive residues at a former storage and reprocessing facility named Latty Avenue near St. Louis, Missouri. The Latty Avenue site is included in ComEd’s indemnification responsibilities discussed above as part of the sale of Cotter. The radioactive residues had been generated initially in connection with the processing of uranium ores as part of the U.S. government’s Manhattan Project. Cotter purchased the residues in 1969 for initial processing at the Latty Avenue facility for the subsequent extraction of uranium and metals. In 1976, the NRC found that the Latty Avenue site had radiation levels exceeding NRC criteria for decontamination of land areas. Latty Avenue was investigated and remediated by the United States Army Corps of Engineers pursuant to funding under the FUSRAP. The DOJ has not yet formally advised the PRPs of the amount that it is seeking, but it is believed to be approximately $90 million . The DOJ and the PRPs agreed to toll the statute of limitations until August 2017 so that settlement discussions could proceed. Based on Generation’s preliminary review, it appears probable that Generation has liability to Cotter under the indemnification agreement and has established an appropriate accrual for this liability. Commencing in February 2012, 63 lawsuits have been filed in the U.S. District Court for the Eastern District of Missouri. Among the defendants were Exelon, Generation and ComEd, all of which were subsequently dismissed from the case, and Cotter, which remains a defendant. The suits allege that individuals living in the North St. Louis area developed some form of cancer due to Cotter's negligent or reckless conduct in processing, transporting, storing, handling and/or disposing of radioactive materials. Plaintiffs have asserted claims for negligence, strict liability, emotional distress, medical monitoring, and violations of the Price-Anderson Act. The complaints do not contain specific damage claims. In the event of a finding of liability, it is reasonably possible that Exelon would be considered liable due to its indemnification responsibilities of Cotter described above. The court has dismissed the lawsuits filed by 30 of the plaintiffs. Pre-trial motions and discovery are proceeding in the remaining cases and a pre-trial scheduling order has been filed with the court. At this stage of the litigation, Generation and ComEd cannot estimate a range of loss, if any. 68 th Street Dump. In 1999, the EPA proposed to add the 68th Street Dump in Baltimore, Maryland to the Superfund National Priorities List, and notified BGE and 19 others that they are PRPs at the site. In March 2004, BGE and other PRPs formed the 68th Street Coalition and entered into consent order negotiations with the EPA to investigate clean-up options for the site under the Superfund Alternative Sites Program. In May 2006, a settlement among the EPA and 19 of the PRPs, including BGE, with respect to investigation of the site became effective. The settlement requires the PRPs, over the course of several years, to identify contamination at the site and recommend clean-up options. The PRPs submitted their investigation of the range of clean-up options in the first quarter of 2011. Although the investigation and options provided to the EPA are still subject to EPA review and selection of a remedy, the range of estimated clean-up costs to be allocated among all of the PRPs is in the range of $50 million to $64 million . On September 30, 2013, EPA issued the Record of Decision identifying its preferred remedial alternative for the site. The estimated cost for the alternative chosen by EPA is consistent with the PRPs estimated range of costs noted above. A wholly owned subsidiary of Generation has agreed to indemnify BGE for most of the costs related to this settlement and clean-up of the site. Based on Generation’s preliminary review, it appears probable that Generation has liability and has established an appropriate accrual which are included in the table above for its share of the estimated clean-up costs. Rossville Ash Site. The Rossville Ash Site is a 32-acre property located in Rosedale, Baltimore County, Maryland, which was used for the placement of fly ash from 1983-2007. The property is owned by Constellation Power Source Generation, LLC (CPSG). In 2008, CPSG investigated and remediated the property by entering it into the Maryland Voluntary Cleanup Program (VCP) to address any historic environmental concerns and ready the site for appropriate future redevelopment. The site was accepted into the program in 2010 and is currently going through the process to remediate the site and receive closure from MDE. Generation currently estimates the remaining cost to close the site to be approximately $6 million which has been fully reserved and included in the table above as of September 30, 2016 . Sauer Dump. On May 30, 2012, BGE was notified by the EPA that it is considered a PRP at the Sauer Dump Superfund site in Dundalk, Maryland. The EPA offered BGE and three other PRPs the opportunity to conduct an environmenta

Supplemental Financial Informat

Supplemental Financial Information (All Registrants)	9 Months Ended
	Sep. 30, 2016
Supplemental Financial Information [Abstract]
Supplemental Financial Information (All Registrants)	19 . Supplemental Financial Information (All Registrants) Supplemental Statement of Operations Information The following tables provide additional information about the Registrants’ Consolidated Statements of Operations and Comprehensive Income for the three and nine months ended September 30, 2016 and 2015 : Three Months Ended September 30, 2016 Successor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Other, Net Decommissioning-related activities: Net realized income on decommissioning trust funds (a) Regulatory agreement units $ 57 $ 57 $ — $ — $ — $ — $ — $ — $ — Non-regulatory agreement units 35 35 — — — — — — — Net unrealized gains on decommissioning trust funds Regulatory agreement units 155 155 — — — — — — — Non-regulatory agreement units 116 116 — — — — — — — Net unrealized losses on pledged assets Zion Station decommissioning (5 ) (5 ) — — — — — — — Regulatory offset to decommissioning trust fund-related activities (b) (168 ) (168 ) — — — — — — — Total decommissioning-related activities 190 190 — — — — — — — Investment income 2 1 — (1 ) — — — — — Interest income related to uncertain income tax positions 8 — — — — — — — — Penalty related to uncertain income tax positions (c) (106 ) — (86 ) — — — — — — AFUDC — Equity 19 — 5 2 5 7 5 1 1 Other 7 (6 ) 1 1 — 12 7 2 1 Other, net $ 120 $ 185 $ (80 ) $ 2 $ 5 $ 19 $ 12 $ 3 $ 2 Successor Predecessor Nine Months Ended September 30, 2016 March 24, 2016 to September 30, 2016 January 1, 2016 to March 23, 2016 Exelon Generation ComEd PECO BGE Pepco DPL ACE PHI PHI Other, Net Decommissioning-related activities: Net realized income on decommissioning trust funds (a) Regulatory agreement units $ 181 $ 181 $ — $ — $ — $ — $ — $ — $ — $ — Non-regulatory agreement units 95 95 — — — — — — — — Net unrealized gains on decommissioning trust funds Regulatory agreement units 286 286 — — — — — — — — Non-regulatory agreement units 216 216 — — — — — — — — Net unrealized losses on pledged assets Zion Station decommissioning (2 ) (2 ) — — — — — — — — Regulatory offset to decommissioning trust fund-related activities (b) (380 ) (380 ) — — — — — — — — Total decommissioning-related activities 396 396 — — — — — — — — Investment income (expense) 14 6 — (1 ) 2 (d) — — — 1 — Long-term lease income 4 — — — — — — — — — Interest income related to uncertain income tax positions 13 — — — — 1 — 1 — — Penalty income related to uncertain income tax positions (c) (106 ) — (86 ) — — — — — — — AFUDC — Equity 43 — 8 6 14 14 3 5 15 7 Loss on debt extinguishment (3 ) (2 ) — — — — — — — — Other 16 (5 ) 6 1 — 13 6 2 15 (11 ) Other, net $ 377 $ 395 $ (72 ) $ 6 $ 16 $ 28 $ 9 $ 8 $ 31 $ (4 ) Three Months Ended September 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Other, Net Decommissioning-related activities: Net realized income on decommissioning trust funds (a) Regulatory agreement units $ 39 $ 39 $ — $ — $ — $ — $ — $ — $ — Non-regulatory agreement units 18 18 — — — — — — — Net unrealized losses on decommissioning trust funds Regulatory agreement units (301 ) (301 ) — — — — — — — Non-regulatory agreement units (218 ) (218 ) — — — — — — — Regulatory offset to decommissioning trust fund-related activities (b) 207 207 — — — — — — — Total decommissioning-related activities (255 ) (255 ) — — — — — — — Investment income (expense) 4 1 — (1 ) 1 (d) — — — — Long-term lease income 4 — — — — — — — — AFUDC — Equity 6 — 1 1 4 2 3 — — Other (3 ) (3 ) 3 1 (1 ) 25 5 4 1 Other, net $ (244 ) $ (257 ) $ 4 $ 1 $ 4 $ 27 $ 8 $ 4 $ 1 Nine Months Ended September 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Other, Net Decommissioning-related activities: Net realized income on decommissioning trust funds (a) Regulatory agreement units $ 203 $ 203 $ — $ — $ — $ — $ — $ — $ — Non-regulatory agreement units 122 122 — — — — — — — Net unrealized losses on decommissioning trust funds Regulatory agreement units (385 ) (385 ) — — — — — — — Non-regulatory agreement units (274 ) (274 ) — — — — — — — Net unrealized gains on pledged assets Zion Station decommissioning 9 9 — — — — — — Regulatory offset to decommissioning trust fund-related activities (b) 129 129 — — — — — — — Total decommissioning-related activities (196 ) (196 ) — — — — — — — Investment income (expense) 6 1 — (1 ) 3 (d) — — — — Long-term lease income 12 — — — — — — — — Interest income related to uncertain income tax positions — 1 — — — — — — 1 AFUDC — Equity 16 — 2 4 10 11 9 1 1 Terminated interest rate swaps (e) (26 ) — — — — — — — — Other 9 1 12 — — 37 12 7 2 Other, net $ (179 ) $ (193 ) $ 14 $ 3 $ 13 $ 48 $ 21 $ 8 $ 4 ____ (a) Includes investment income and realized gains and losses on sales of investments of the trust funds. (b) Includes the elimination of NDT fund activity for the Regulatory Agreement Units, including the elimination of net income taxes related to all NDT fund activity for those units. See Note 16 — Asset Retirement Obligations of the Exelon 2015 Form 10-K for additional information regarding the accounting for nuclear decommissioning. (c) See Note 11 — Income Taxes for discussion of the penalty related to the Tax Court's decision on Exelon's like-kind exchange tax position. (d) Relates to the cash return on BGE’s rate stabilization deferral. See Note 3 — Regulatory Matters of the Exelon 2015 Form 10-K for additional information regarding the rate stabilization deferral. (e) In January 2015, in connection with Generation's $750 million issuance of five-year Senior Unsecured Notes, Exelon terminated certain floating-to-fixed interest rate swaps. As the original forecasted transactions were a series of future interest payments over a ten year period, a portion of the anticipated interest payments were probable not to occur. As a result, $26 million of anticipated payments were reclassified from AOCI to Other, net in Exelon's Consolidated Statement of Operations and Comprehensive Income. The following utility taxes are included in revenues and expenses for the three and nine months ended September 30, 2016 and 2015 . Generation’s utility tax expense represents gross receipts tax related to its retail operations and the utility registrants' utility tax expense represents municipal and state utility taxes and gross receipts taxes related to their operating revenues. The offsetting collection of utility taxes from customers is recorded in revenues on the Registrants’ Consolidated Statements of Operations and Comprehensive Income. Three Months Ended September 30, 2016 Successor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Utility taxes $ 255 $ 35 $ 67 $ 40 $ 21 $ 92 $ 87 $ 5 $ — Successor Predecessor Nine Months Ended September 30, 2016 March 24, 2016 to September 30, 2016 January 1, 2016 to March 23, 2016 Exelon Generation ComEd PECO BGE Pepco DPL ACE PHI PHI Utility taxes $ 624 $ 90 $ 186 $ 106 $ 66 $ 240 $ 14 $ — $ 176 $ 78 Three Months Ended September 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Utility taxes $ 151 $ 28 $ 63 $ 37 $ 23 $ 86 $ 82 $ 4 $ — Nine Months Ended September 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Utility taxes $ 430 $ 79 $ 180 $ 104 $ 67 $ 253 $ 239 $ 14 $ — Supplemental Cash Flow Information The following tables provide additional information regarding the Registrants’ Consolidated Statements of Cash Flows for the nine months ended September 30, 2016 and 2015 : Successor Predecessor Nine Months Ended September 30, 2016 March 24, 2016 to September 30, 2016 January 1, 2016 to March 23, 2016 Exelon Generation ComEd PECO BGE Pepco DPL ACE PHI PHI Depreciation, amortization, accretion and depletion Property, plant and equipment (a) $ 2,490 $ 1,297 $ 524 $ 181 $ 223 $ 128 $ 82 $ 61 $ 215 $ 94 Amortization of regulatory assets (a) 293 — 49 20 84 93 38 69 140 58 Amortization of intangible assets, net (a) 38 32 — — — — — — — — Amortization of energy contract assets and liabilities (b) (7 ) (7 ) — — — — — — — — Nuclear fuel (c) 862 862 — — — — — — — — ARO accretion (d) 333 332 1 — — — — — — — Total depreciation, amortization, accretion and depletion $ 4,009 $ 2,516 $ 574 $ 201 $ 307 $ 221 $ 120 $ 130 $ 355 $ 152 Nine Months Ended September 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Depreciation, amortization, accretion and depletion Property, plant and equipment (a) $ 1,648 $ 739 $ 471 $ 179 $ 216 $ 292 $ 122 $ 76 $ 57 Amortization of regulatory assets (a) 131 — 57 19 55 182 69 37 78 Amortization of intangible assets, net (a) 39 35 — — — — — — — Amortization of energy contract assets and liabilities (b) (20 ) (19 ) — — — — — — — Nuclear fuel (c) 841 841 — — — — — — — ARO accretion (d) 291 291 — — — — — — — Total depreciation, amortization, accretion and depletion $ 2,930 $ 1,887 $ 528 $ 198 $ 271 $ 474 $ 191 $ 113 $ 135 ________ (a) Included in Depreciation and amortization on the Registrants' Consolidated Statements of Operations and Comprehensive Income. (b) Included in Operating revenues or Purchased power and fuel expense on the Registrants’ Consolidated Statements of Operations and Comprehensive Income. (c) Included in Purchased power and fuel expense on the Registrants’ Consolidated Statements of Operations and Comprehensive Income. (d) Included in Operating and maintenance expense on the Registrants’ Consolidated Statements of Operations and Comprehensive Income. Successor Predecessor Nine Months Ended September 30, 2016 March 24, 2016 to September 30, 2016 January 1, 2016 to March 23, 2016 Exelon Generation ComEd PECO BGE Pepco DPL ACE PHI PHI Other non-cash operating activities: Pension and non-pension postretirement benefit costs $ 458 $ 163 $ 124 $ 25 $ 50 $ 24 $ 13 $ 11 $ 58 $ 23 Loss from equity method investments 15 16 — — — — — — — — Provision for uncollectible accounts 107 14 31 24 12 15 12 18 27 16 Stock-based compensation costs 88 — — — — — — — — 3 Other decommissioning-related activity (a) (237 ) (237 ) — — — — — — — — Energy-related options (b) (20 ) (20 ) — — — — — — — — Amortization of regulatory asset related to debt costs 7 — 3 1 — 2 — 1 2 1 Amortization of rate stabilization deferral 62 — — — 62 3 3 — — 5 Amortization of debt fair value adjustment (9 ) (9 ) — — — — — — — — Discrete impacts from EIMA (c) (36 ) — (36 ) — — — — — — — Amortization of debt costs 26 12 (3 ) 2 3 — — — — — Provision for excess and obsolete inventory 74 70 4 — — 1 1 1 — 1 Merger-related commitments (d)(e) 508 3 — — — 125 73 110 308 — Severance costs 130 57 — — — — — — 53 — Asset retirement costs — — — — — — 5 2 — — Lower of cost or market inventory adjustment 36 36 — — — — — — — — Other 15 24 (1 ) (3 ) (18 ) (2 ) (8 ) (5 ) (7 ) (3 ) Total other non-cash operating activities $ 1,224 $ 129 $ 122 $ 49 $ 109 $ 168 $ 99 $ 138 $ 441 $ 46 Non-cash investing and financing activities: Change in capital expenditures not paid $ (338 ) $ (289 ) $ (42 ) $ (4 ) $ 17 $ 15 $ (10 ) $ 2 $ (5 ) $ 11 Fair value of net assets contributed to Generation in connection with the PHI merger, net of cash (d)(f) — 119 — — — — — — — — Fair value of net assets distributed to Exelon in connection with the PHI Merger, net of cash (d)(f) — — — — — — — — 129 — Fair value of pension obligation transferred in connection with the PHI Merger — — — — — — — — 53 — Assumption of member purchase liability — — — — — — — — 29 — Assumption of merger commitment liability — — — — — 33 — — 33 — Change in PPE related to ARO update 476 476 — — — — — — — — Indemnification of like-kind exchange position (g) — — 157 — — — — — — — Non-cash financing of capital projects 84 84 — — — — — — — — Nine Months Ended September 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Other non-cash operating activities: Pension and non-pension postretirement benefit costs $ 476 $ 200 $ 155 $ 29 $ 49 $ 73 $ 22 $ 11 $ 11 Loss from equity method investments 3 4 — — — — — — — Provision for uncollectible accounts 114 15 46 37 15 49 15 18 15 Stock-based compensation costs 102 — — — — 9 — — — Other decommissioning-related activity (a) (31 ) (31 ) — — — — — — — Energy-related options (b) 18 18 — — — — — — — Amortization of regulatory asset related to debt costs — — — — — 4 2 — — Amortization of rate stabilization deferral 60 — — — 60 3 3 1 — Amortization of debt fair value adjustment (34 ) (9 ) — — — — — — — Discrete impacts from EIMA (c) 101 — 101 — — — — — — Amortization of debt costs 43 12 3 2 2 1 — — — Provision for excess and obsolete inventory 7 8 — — — 1 — — — Lower of cost or market inventory adjustment 15 15 — — — — — — — Other (18 ) (5 ) 7 1 (15 ) 3 — 1 1 Total other non-cash operating activities $ 856 $ 227 $ 312 $ 69 $ 111 $ 143 $ 42 $ 31 $ 27 Non-cash investing and financing activities: Change in capital expenditures not paid $ 59 $ 48 $ 62 $ (23 ) $ (14 ) $ (3 ) $ (1 ) $ 2 $ — Nuclear fuel procurement (d) — — — — — — — — — Change in PPE related to ARO update 811 811 — — — — — — — Indemnification of like-kind exchange position (g) — — 5 — — — — — — Non-cash financing of capital projects 52 52 — — — — — — — Long-term software licensing agreement (f) 95 — — — — — — — — ________ (a) Includes the elimination of NDT fund activity for the Regulatory Agreement Units, including the elimination of operating revenues, ARO accretion, ARC amortization, investment income and income taxes related to all NDT fund activity for these units. See Note 16 - Asset Retirement Obligations of the Exelon 2015 Form 10-K for additional information regarding the accounting for nuclear decommissioning. (b) Includes option premiums reclassified to realized at the settlement of the underlying contracts and recorded in Operating revenues. (c) Reflects the change in distribution rates pursuant to EIMA, which allows for the recovery of costs by a utility through a pre-established performance-based formula rate tariff. See Note 5 — Regulatory Matters for more information. (d) See Note 4 — Mergers, Acquisitions and Dispositions for additional information related to the merger with PHI. (e) Excludes $5 million of forgiveness of Accounts receivable related to merger commitments recorded in connection with the PHI Merger, the balance is included within Provision for uncollectible accounts. (f) Immediately following closing of the PHI Merger, the net assets associated with PHI's unregulated business interests were distributed by PHI to Exelon. Exelon contributed a portion of such net assets to Generation. (g) See Note 11 — Income Taxes for discussion of the like-kind exchange tax position. Supplemental Balance Sheet Information The following tables provide additional information about assets and liabilities of the Registrants as of September 30, 2016 and December 31, 2015 : Successor September 30, 2016 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Property, plant and equipment: Accumulated depreciation and amortization $ 18,354 (a) $ 10,004 (a) $ 3,841 $ 3,213 $ 3,198 $ 146 $ 3,026 $ 1,171 $ 1,008 Accounts receivable: Allowance for uncollectible accounts $ 330 $ 85 $ 82 $ 78 $ 39 $ 46 $ 15 $ 14 $ 17 Predecessor December 31, 2015 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Property, plant and equipment: Accumulated depreciation and amortization $ 16,375 (b) $ 8,639 (b) $ 3,710 $ 3,101 $ 3,016 $ 5,341 $ 2,929 $ 1,139 $ 968 Accounts receivable: Allowance for uncollectible accounts $ 284 $ 77 $ 75 $ 83 $ 49 $ 56 $ 17 $ 17 $ 17 _______ (a) Includes accumulated amortization of nuclear fuel in the reactor core of $3,198 million . (b) Includes accumulated amortization of nuclear fuel in the reactor core of $2,861 million . PECO Installment Plan Receivables (Exelon and PECO) PECO enters into payment agreements with certain delinquent customers, primarily residential, seeking to restore their service, as required by the PAPUC. Customers with past due balances that meet certain income criteria are provided the option to enter into an installment payment plan, some of which have terms greater than one year, to repay past due balances in addition to paying for their ongoing service on a current basis. The receivable balance for these payment agreement receivables is recorded in accounts receivable for the current portion and other deferred debits and other assets for the noncurrent portion. The net receivable balance for installment plans with terms greater than one year was $16 million and $15 million as of September 30, 2016 and December 31, 2015 , respectively. The allowance for uncollectible accounts reserve methodology and assessment of the credit quality of the installment plan receivables are consistent with the customer accounts receivable methodology discussed in Note 1 — Significant Accounting Policies of the Exelon 2015 Form 10-K. The allowance for uncollectible accounts balance associated with these receivables at September 30, 2016 of $14 million consists of $0 million , $3 million and $11 million for low risk, medium risk and high risk segments, respectively. The allowance for uncollectible accounts balance at December 31, 2015 of $15 million consists of $1 million , $3 million and $11 million for low risk, medium risk and high risk segments, respectively. The balance of the payment agreement is billed to the customer in equal monthly installments over the term of the agreement. Installment receivables outstanding as of September 30, 2016 and December 31, 2015 include balances not yet presented on the customer bill, accounts currently billed and an immaterial amount of past due receivables. When a customer defaults on its payment agreement, the terms of which are defined by plan type, the entire balance of the agreement becomes due and the balance is reclassified to current customer accounts receivable and reserved for in accordance with the methodology discussed in Note 1 — Significant Accounting Policies of the Exelon 2015 Form 10-K.

Segment Information (All Regist

Segment Information (All Registrants)	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Segment Information (All Registrants)	20 . Segment Information (All Registrants) Operating segments for each of the Registrants are determined based on information used by the chief operating decision maker(s) (CODM) in deciding how to evaluate performance and allocate resources at each of the Registrants. In the first quarter of 2016, following the consummation of the PHI Merger, three new reportable segments were added: Pepco, DPL and ACE. As a result, Exelon has twelve reportable segments, which include ComEd, PECO, BGE, PHI's three reportable segments consisting of Pepco, DPL, and ACE, and Generation’s six power marketing reportable segments consisting of the Mid-Atlantic, Midwest, New England, New York, ERCOT and all other power regions referred to collectively as “Other Power Regions”, which includes activities in the South, West and Canada. ComEd, PECO, BGE, Pepco, DPL and ACE each represent a single reportable segment, and as such, no separate segment information is provided for these Registrants. Exelon, ComEd, PECO, BGE, Pepco, DPL and ACE's CODMs evaluate the performance of and allocate resources to ComEd, PECO, BGE, Pepco, DPL and ACE based on net income and return on equity. Effective with the consummation of the PHI Merger, PHI's reportable segments have changed based on the information used by the CODM to evaluate performance and allocate resources. PHI's reportable segments consist of Pepco, DPL and ACE. PHI's Predecessor periods' segment information has been recast to conform to the current presentation. The reclassification of the segment information did not impact PHI's reported consolidated revenues or net income. PHI's CODM evaluates the performance of and allocates resources to Pepco, DPL and ACE based on net income and return on equity. The basis for Generation's reportable segments is the integrated management of its electricity business that is located in different geographic regions, and largely representative of the footprints of ISO/RTO and/or NERC regions, which utilize multiple supply sources to provide electricity through various distribution channels (wholesale and retail). Generation's hedging strategies and risk metrics are also aligned to these same geographic regions. Descriptions of each of Generation’s six reportable segments are as follows: • Mid-Atlantic represents operations in the eastern half of PJM, which includes New Jersey, Maryland, Virginia, West Virginia, Delaware, the District of Columbia and parts of Pennsylvania and North Carolina. • Midwest represents operations in the western half of PJM, which includes portions of Illinois, Pennsylvania, Indiana, Ohio, Michigan, Kentucky and Tennessee, and the United States footprint of MISO, excluding MISO’s Southern Region, which covers all or most of North Dakota, South Dakota, Nebraska, Minnesota, Iowa, Wisconsin, the remaining parts of Illinois, Indiana, Michigan and Ohio not covered by PJM, and parts of Montana, Missouri and Kentucky. • New England represents the operations within ISO-NE covering the states of Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island and Vermont. • New York represents operations within ISO-NY, which covers the state of New York in its entirety. • ERCOT represents operations within Electric Reliability Council of Texas, covering most of the state of Texas. • Other Power Regions : • South represents operations in the FRCC, MISO’s Southern Region, and the remaining portions of the SERC not included within MISO or PJM, which includes all or most of Florida, Arkansas, Louisiana, Mississippi, Alabama, Georgia, Tennessee, North Carolina, South Carolina and parts of Missouri, Kentucky and Texas. Generation’s South region also includes operations in the SPP, covering Kansas, Oklahoma, most of Nebraska and parts of New Mexico, Texas, Louisiana, Missouri, Mississippi and Arkansas. • West represents operations in the WECC, which includes California ISO, and covers the states of California, Oregon, Washington, Arizona, Nevada, Utah, Idaho, Colorado and parts of New Mexico, Wyoming and South Dakota. • Canada represents operations across the entire country of Canada and includes AESO, OIESO and the Canadian portion of MISO. The CODMs for Exelon and Generation evaluate the performance of Generation’s power marketing activities and allocate resources based on revenue net of purchased power and fuel expense (RNF). Generation believes that RNF is a useful measurement of operational performance. RNF is not a presentation defined under GAAP and may not be comparable to other companies’ presentations or deemed more useful than the GAAP information provided elsewhere in this report. Generation’s operating revenues include all sales to third parties and affiliated sales to the Utility Registrants. Purchased power costs include all costs associated with the procurement and supply of electricity including capacity, energy and ancillary services. Fuel expense includes the fuel costs for Generation’s owned generation and fuel costs associated with tolling agreements. The results of Generation's other business activities are not regularly reviewed by the CODM and are therefore not classified as operating segments or included in the regional reportable segment amounts. These activities include natural gas, as well as other miscellaneous business activities that are not significant to Generation's overall operating revenues or results of operations. Further, Generation’s unrealized mark-to-market gains and losses on economic hedging activities and its amortization of certain intangible assets and liabilities relating to commodity contracts recorded at fair value from mergers and acquisitions are also not included in the regional reportable segment amounts. Exelon and Generation do not use a measure of total assets in making decisions regarding allocating resources to or assessing the performance of these reportable segments. An analysis and reconciliation of the Registrants’ reportable segment information to the respective information in the consolidated financial statements for the three and nine months ended September 30, 2016 and 2015 is as follows: Three Months Ended September 30, 2016 and 2015 Successor Generation (a) ComEd PECO BGE PHI (b) Other (c) Intersegment Exelon Operating revenues (d) : 2016 Competitive businesses electric revenues $ 4,322 $ — $ — $ — $ — $ — $ (499 ) $ 3,823 Competitive businesses natural gas revenues 326 — — — — — — 326 Competitive businesses other revenues 387 — — — — — (1 ) 386 Rate-regulated electric revenues — 1,497 740 735 1,366 — (8 ) 4,330 Rate-regulated natural gas revenues — — 48 77 17 — (5 ) 137 Shared service and other revenues — — — — 11 362 (373 ) — 2015 Competitive businesses electric revenues $ 4,299 $ — $ — $ — $ — $ — $ (204 ) $ 4,095 Competitive businesses natural gas revenues 347 — — — — — — 347 Competitive businesses other revenues 122 — — — — — — 122 Rate-regulated electric revenues — 1,376 691 655 — — (1 ) 2,721 Rate-regulated natural gas revenues — — 49 70 — — (3 ) 116 Shared service and other revenues — — — — — 348 (348 ) — Intersegment revenues (e) : 2016 $ 500 $ 4 $ 2 $ 7 $ 11 $ 362 $ (885 ) $ 1 2015 205 1 1 3 — 347 (555 ) 2 Net income (loss): 2016 $ 271 $ 37 $ 122 $ 56 $ 166 $ (125 ) $ (1 ) $ 526 2015 332 149 90 54 — (36 ) (2 ) 587 Total assets: September 30, 2016 $ 47,568 $ 28,020 $ 11,041 $ 8,857 $ 21,063 $ 9,883 $ (11,897 ) $ 114,535 December 31, 2015 46,529 26,532 10,367 8,295 — 15,389 (11,728 ) 95,384 __________ (a) Generation includes the six power marketing reportable segments shown below: Mid-Atlantic, Midwest, New England, New York, ERCOT and Other Power Regions. Intersegment revenues for Generation for the three months ended September 30, 2016 include revenue from sales to PECO of $91 million and sales to BGE of $183 million in the Mid-Atlantic region, and sales to ComEd of $20 million in the Midwest region. For the three months ended September 30, 2015 , intersegment revenues for Generation include revenue from sales to PECO of $61 million and sales to BGE of $141 million in the Mid-Atlantic region, and sales to ComEd of $2 million in the Midwest region. For the Successor period of three months ended September 30, 2016 , intersegment revenues for Generation include revenue from sales to Pepco of $128 million , sales to DPL of $63 million , and sales to ACE of $15 million in the Mid-Atlantic region. (b) Amounts included represent activity for PHI's successor period, three months ended September 30, 2016 . PHI includes the three reportable segments: Pepco, DPL and ACE. See tables below for PHI's predecessor periods, including Pepco, DPL and ACE, for January 1, 2016 to March 23, 2016 and for the nine months ended September 30, 2015 . (c) Other primarily includes Exelon’s corporate operations, shared service entities and other financing and investment activities. (d) Includes gross utility tax receipts from customers. The offsetting remittance of utility taxes to the governing bodies is recorded in expenses on the Registrants’ Consolidated Statements of Operations and Comprehensive Income. See Note 19 — Supplemental Financial Information for total utility taxes for the three months ended September 30, 2016 and 2015 . (e) Intersegment revenues exclude sales to unconsolidated affiliates. The intersegment profit associated with Generation’s sale of certain products and services by and between Exelon’s segments is not eliminated in consolidation due to the recognition of intersegment profit in accordance with regulatory accounting guidance. For Exelon, these amounts are included in Operating revenues in the Consolidated Statements of Operations and Comprehensive Income. Generation total revenues: Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 Revenues (a) Intersegment Total Revenues (a)(c) Intersegment (c) Total (c) Mid-Atlantic $ 1,813 $ (13 ) $ 1,800 $ 1,640 $ (8 ) $ 1,632 Midwest 1,163 1 1,164 1,152 (1 ) 1,151 New England 455 (4 ) 451 520 — 520 New York 331 (8 ) 323 254 (4 ) 250 ERCOT 289 6 295 317 (1 ) 316 Other Power Regions 271 (33 ) 238 416 (40 ) 376 Total Revenues for Reportable Segments 4,322 (51 ) 4,271 4,299 (54 ) 4,245 Other (b) 713 51 764 469 54 523 Total Generation Consolidated Operating Revenues $ 5,035 $ — $ 5,035 $ 4,768 $ — $ 4,768 __________ (a) Includes all wholesale and retail electric sales to third parties and affiliated sales to the Utility Registrants. (b) Other represents activities not allocated to a region. See text above for a description of included activities. Includes a $21 million decrease and $3 million decrease to revenues for the amortization of intangible assets and liabilities related to commodity contracts recorded at fair value for the three months ended September 30, 2016 and 2015 , respectively, unrealized mark-to-market gains of $187 million and losses of $7 million for the three months ended September 30, 2016 and 2015 , respectively, and elimination of intersegment revenues. (c) Exelon corrected an error in the September 30, 2015 balances within Intersegment Revenue and Revenue from external customers for an overstatement of $54 million of Intersegment Revenue for Reportable Segments for the three months ended September 30, 2015 , an understatement of Revenue from external customers for Reportable Segments of $54 million for the three months ended September 30, 2015 , an understatement of $54 million of Intersegment Revenue for Other for the three months ended September 30, 2015 , and an overstatement of Revenue from external customers for Other of $54 million for the three months ended September 30, 2015 . This error is not considered material to any prior period, and there is no impact to Total Revenues. Generation total revenues net of purchased power and fuel expense: Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 RNF (a) Intersegment RNF Total RNF RNF (a)(c) Intersegment RNF (c) Total RNF (c) Mid-Atlantic $ 881 $ 6 $ 887 $ 979 $ 18 $ 997 Midwest 782 (1 ) 781 760 (4 ) 756 New England 170 (10 ) 160 148 (15 ) 133 New York 195 (1 ) 194 157 13 170 ERCOT 144 (51 ) 93 166 (55 ) 111 Other Power Regions 143 (66 ) 77 154 (71 ) 83 Total Revenues net of purchased power and fuel for Reportable Segments 2,315 (123 ) 2,192 2,364 (114 ) 2,250 Other (b) 131 123 254 (115 ) 114 (1 ) Total Generation Revenues net of purchased power and fuel expense $ 2,446 $ — $ 2,446 $ 2,249 $ — $ 2,249 __________ (a) Includes purchases and sales from/to third parties and affiliated sales to the Utility Registrants. (b) Other represents activities not allocated to a region. See text above for a description of included activities. Includes a $22 million decrease and a $4 million decrease to RNF for the amortization of intangible assets and liabilities related to commodity contracts for the three months ended September 30, 2016 and 2015 , respectively, unrealized mark-to-market gains of $88 million and losses of $139 million for the three months ended September 30, 2016 and 2015 , respectively, accelerated nuclear fuel amortization associated with nuclear decommissioning as discussed in Note 7 — Early Nuclear Plant Retirements of the Combined Notes to Consolidated Financial Statements of $28 million for the three months ended September 30, 2016 , and the elimination of intersegment revenue net of purchased power and fuel expense. (c) Exelon corrected an error in the September 30, 2015 balances within Intersegment RNF and RNF from external customers for an understatement of $12 million of Intersegment RNF for Reportable Segments for the three months ended September 30, 2015 , and an overstatement of $12 million of Intersegment RNF for Other for the three months ended September 30, 2015 . This also included an understatement of total RNF for Reportable Segments and an overstatement of total RNF for Other of $13 million for the three months ended September 30, 2015 . The error is not considered material to any prior period, and there is no net impact to Generation Total RNF for 2015. Successor and Predecessor PHI: Pepco DPL ACE Other (b) Intersegment PHI Operating revenues (a) : Three months ended September 30, 2016 - Successor Rate-regulated electric revenues $ 635 $ 314 $ 421 $ — $ (4 ) $ 1,366 Rate-regulated natural gas revenues — 17 — — 17 Shared service and other revenues — — — 11 — 11 Three months ended September 30, 2015 - Predecessor Rate-regulated electric revenues $ 592 $ 295 $ 386 $ 44 $ — $ 1,317 Rate-regulated natural gas revenues — 19 — — — 19 Shared service and other revenues — — — — — — Intersegment revenues (e) : Three months ended September 30, 2016 - Successor $ 1 $ 2 $ 1 $ 11 $ (4 ) $ 11 Three months ended September 30, 2015 - Predecessor 1 1 1 — (3 ) — Net income (loss): Three months ended September 30, 2016 - Successor $ 79 $ 44 $ 47 $ (15 ) $ 11 $ 166 Three months ended September 30, 2015 - Predecessor 60 15 22 (6 ) — 91 Total assets: September 30, 2016 - Successor $ 7,219 $ 4,023 $ 3,507 $ 11,057 $ (4,743 ) $ 21,063 December 31, 2015 - Predecessor 6,908 3,969 3,387 7,162 (5,238 ) 16,188 __________ (a) Includes gross utility tax receipts from customers. The offsetting remittance of utility taxes to the governing bodies is recorded in expenses on the Registrants’ Consolidated Statements of Operations and Comprehensive Income. See Note 19 — Supplemental Financial Information for total utility taxes for the three months ended September 30, 2016 and 2015 . (b) Other primarily includes PHI’s corporate operations, shared service entities and other financing and investment activities. For the predecessor periods presented, Other includes the activity of PHI’s unregulated businesses which were distributed to Exelon and Generation as a result of the PHI Merger. Nine Months Ended September 30, 2016 and 2015 Successor Generation (a) ComEd PECO BGE PHI (b) Other (c) Intersegment Exelon Operating revenues (d) : 2016 Competitive businesses electric revenues $ 11,677 $ — $ — $ — $ — $ — $ (1,118 ) $ 10,559 Competitive businesses natural gas revenues 1,515 — — — — — — 1,515 Competitive businesses other revenues 171 — — — — — (2 ) 169 Rate-regulated electric revenues — 4,031 1,971 1,998 2,485 — (24 ) 10,461 Rate-regulated natural gas revenues — — 322 423 46 — (10 ) 781 Shared service and other revenues — — — — 34 1,166 (1,199 ) 1 2015 Competitive businesses electric revenues $ 12,360 $ — $ — $ — $ — $ — $ (564 ) $ 11,796 Competitive businesses natural gas revenues 1,901 — — — — — — 1,901 Competitive businesses other revenues 580 — — — — — 1 581 Rate-regulated electric revenues — 3,709 1,950 1,908 — — (3 ) 7,564 Rate-regulated natural gas revenues — — 436 480 — — (12 ) 904 Shared service and other revenues — — — — — 1,007 (1,007 ) — Intersegment revenues (e) : 2016 $ 1,121 $ 12 $ 5 $ 16 $ 34 $ 1,166 $ (2,351 ) $ 3 2015 567 3 1 10 — 1,003 (1,581 ) 3 Net income (loss): 2016 $ 556 $ 297 $ 346 $ 191 $ (91 ) $ (340 ) $ (3 ) $ 956 2015 1,208 339 299 212 — (96 ) (3 ) 1,959 _________ (a) Generation includes the six power marketing reportable segments shown below: Mid-Atlantic, Midwest, New England, New York, ERCOT and Other Power Regions. Intersegment revenues for Generation for the nine months ended September 30, 2016 include revenue from sales to PECO of $234 million and sales to BGE of $489 million in the Mid-Atlantic region, and sales to ComEd of $38 million in the Midwest region. For the nine months ended September 30, 2015 , intersegment revenues for Generation include revenue from sales to PECO of $173 million and sales to BGE of $376 million in the Mid-Atlantic region, and sales to ComEd of $17 million in the Midwest region. For the Successor period of March 24, 2016 to September 30, 2016 , intersegment revenues for Generation include revenue from sales to Pepco of $223 million , sales to DPL of $109 million , and sales to ACE of $28 million in the Mid-Atlantic region. (b) Amounts included represent activity for PHI's successor period, March 24, 2016 through September 30, 2016 . PHI includes the three reportable segments: Pepco, DPL and ACE. See tables below for PHI's predecessor periods, including Pepco, DPL and ACE, for January 1, 2016 to March 23, 2016 and for the nine months ended September 30, 2015 . (c) Other primarily includes Exelon’s corporate operations, shared service entities and other financing and investment activities. (d) Includes gross utility tax receipts from customers. The offsetting remittance of utility taxes to the governing bodies is recorded in expenses on the Registrants’ Consolidated Statements of Operations and Comprehensive Income. See Note 19 — Supplemental Financial Information for total utility taxes for the nine months ended September 30, 2016 and 2015 . (e) Intersegment revenues exclude sales to unconsolidated affiliates. The intersegment profit associated with Generation’s sale of certain products and services by and between Exelon’s segments is not eliminated in consolidation due to the recognition of intersegment profit in accordance with regulatory accounting guidance. For Exelon, these amounts are included in Operating revenues in the Consolidated Statements of Operations and Comprehensive Income. Generation total revenues: Nine Months Ended September 30, 2016 Nine Months Ended September 30, 2015 Revenues (a) Intersegment Total Revenues (a)(c) Intersegment (c) Total (c) Mid-Atlantic $ 4,776 $ (40 ) $ 4,736 $ 4,560 $ (69 ) $ 4,491 Midwest 3,330 13 3,343 3,634 (1 ) 3,633 New England 1,278 (6 ) 1,272 1,752 (6 ) 1,746 New York 906 (33 ) 873 783 (5 ) 778 ERCOT 659 6 665 691 (4 ) 687 Other Power Regions 728 (42 ) 686 940 (60 ) 880 Total Revenues for Reportable Segments 11,677 (102 ) 11,575 12,360 (145 ) 12,215 Other (b) 1,686 102 1,788 2,481 145 2,626 Total Generation Consolidated Operating Revenues $ 13,363 $ — $ 13,363 $ 14,841 $ — $ 14,841 __________ (a) Includes all wholesale and retail electric sales to third parties and affiliated sales to the Utility Registrants. (b) Other represents activities not allocated to a region. See text above for a description of included activities. Includes a $10 million decrease to revenues and a $19 million increase to revenues for the amortization of intangible assets and liabilities related to commodity contracts recorded at fair value for the nine months ended September 30, 2016 and 2015 , respectively, unrealized mark-to-market losses of $366 million and gains of $171 million for the nine months ended September 30, 2016 and 2015 , respectively, and elimination of intersegment revenues. (c) Exelon corrected an error in the September 30, 2015 balances within Intersegment Revenue and Revenue from external customers for an overstatement of $144 million of Intersegment Revenue for Reportable Segments for the nine months ended September 30, 2015 , an understatement of Revenue from external customers for Reportable Segments of $144 million for the nine months ended September 30, 2015 , an understatement of $144 million of Intersegment Revenue for Other for the nine months ended September 30, 2015 , and an overstatement of Revenue from external customers for Other of $144 million for the nine months ended September 30, 2015 . This error is not considered material to any prior period, and there is no impact to Total Revenues. Generation total revenues net of purchased power and fuel expense: Nine Months Ended September 30, 2016 Nine Months Ended September 30, 2015 RNF from external customers (a) Intersegment RNF Total RNF RNF from external customers (a)(c) Intersegment RNF (c) Total RNF (c) Mid-Atlantic $ 2,541 $ 15 $ 2,556 $ 2,679 $ (2 ) $ 2,677 Midwest 2,225 4 2,229 2,220 (15 ) 2,205 New England 373 (23 ) 350 425 (46 ) 379 New York 607 (15 ) 592 462 40 502 ERCOT 335 (104 ) 231 344 (109 ) 235 Other Power Regions 357 (104 ) 253 341 (148 ) 193 Total Revenues net of purchased power and fuel expense for Reportable Segments 6,438 (227 ) 6,211 6,471 (280 ) 6,191 Other (b) 316 227 543 570 280 850 Total Generation Revenues net of purchased power and fuel expense $ 6,754 $ — $ 6,754 $ 7,041 $ — $ 7,041 __________ (a) Includes purchases and sales from/to third parties and affiliated sales to the Utility Registrants. (b) Other represents activities not allocated to a region. See text above for a description of included activities. Includes a $15 million decrease to RNF and a $20 million increase to RNF for the amortization of intangible assets and liabilities related to commodity contracts for the nine months ended September 30, 2016 and 2015 , respectively, unrealized mark-to-market losses of $113 million and gains of $258 million for the nine months ended September 30, 2016 and 2015 , respectively, accelerated nuclear fuel amortization associated with nuclear decommissioning as discussed in Note 7 - Early Nuclear Plant Retirements of the Combined Notes to Consolidated Financial Statements of $38 million for the nine months ended September 30, 2016 , and the elimination of intersegment revenue net of purchased power and fuel expense. (c) Exelon corrected an error in the September 30, 2015 balances within Intersegment RNF and RNF from external customers for an understatement of $22 million of Intersegment RNF for Reportable Segments for the nine months ended September 30, 2015 , an understatement of RNF from external customers for Reportable Segments of $6 million for the nine months ended September 30, 2015 , an overstatement of $22 million of Intersegment RNF for Other for the nine months ended September 30, 2015 , and an overstatement of RNF from external customers for Other of $6 million for the nine months ended September 30, 2015 . This also included an understatement of total RNF for Reportable Segments and an overstatement of total RNF for Other of $28 million for the nine months ended September 30, 2015 . The error is not considered material to any prior period, and there is no net impact to Generation Total RNF for 2015. Successor and Predecessor PHI: Pepco DPL ACE Other (b) Intersegment PHI Operating revenues (a) : March 24, 2016 to September 30, 2016 - Successor Rate-regulated electric revenues $ 1,184 $ 593 $ 714 $ 3 $ (9 ) $ 2,485 Rate-regulated natural gas revenues — 46 — — — 46 Shared service and other revenues — — — 34 — 34 January 1, 2016 to March 23, 2016 - Predecessor Rate-regulated electric revenues $ 511 $ 279 $ 268 $ 42 $ (4 ) $ 1,096 Rate-regulated natural gas revenues — 56 — 1 — 57 Shared service and other revenues — — — — — — Nine months ended September 30, 2015 - Predecessor Rate-regulated electric revenues $ 1,641 $ 875 $ 1,003 $ 161 $ — $ 3,680 Rate-regulated natural gas revenues — 129 — — — 129 Shared service and other revenues — — — — — — Intersegment revenues: March 24, 2016 to September 30, 2016 - Successor $ 2 $ 4 $ 2 $ 35 $ (9 ) $ 34 January 1, 2016 to March 23, 2016 - Predecessor 1 2 1 — (4 ) — Nine months ended September 30, 2015 - Predecessor 4 4 2 — (10 ) — Net income (loss): March 24, 2016 to September 30, 2016 - Successor $ (12 ) $ (42 ) $ (55 ) $ (16 ) $ 34 $ (91 ) January 1, 2016 to March 23, 2016 - Predecessor 32 26 5 (44 ) — 19 Nine months ended September 30, 2015 - Predecessor 128 55 37 (23 ) — 197 _________ (a) Includes gross utility tax receipts from customers. The offsetting remittance of utility taxes to the governing bodies is recorded in expenses on the Registrants’ Consolidated Statements of Operations and Comprehensive Income. See Note 19 — Supplemental Financial Information for total utility taxes for the nine months ended September 30, 2016 and 2015 . (b) Other primarily includes PHI’s corporate operations, shared service entities and other financing and investment activities. For the predecessor periods presented, Other includes the activity of PHI’s unregulated businesses which were distributed to Exelon and Generation as a result of the PHI Merger.

Significant Accounting Polici27

Significant Accounting Policies Significant Accounting Policies	9 Months Ended
	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
New Accounting Pronouncements, Policy [Policy Text Block]	New Accounting Pronouncements (All Registrants) Exelon has identified the following new accounting standards that have been recently adopted. Disclosures for Investments in Certain Entities that Calculate Net Asset Value per Share In May 2015, the FASB issued authoritative guidance that removes the requirement to categorize within the fair value hierarchy all investments for which fair value is measured using the net asset value per share practical expedient. Investments measured at net asset value per share using the practical expedient will be presented as a reconciling item between the fair value hierarchy disclosure and the investment line item on the Balance Sheet. The guidance also simplified the disclosure requirements for investments valued using the practical expedient. The guidance is effective for the Registrants for fiscal years beginning after December 15, 2015. The Registrants adopted the standard in the first quarter of 2016, and applied the guidance retrospectively to all prior periods presented. The adoption of this guidance had no impact on the Registrants’ Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income and Consolidated Statements of Cash Flows. See Note 8 - Fair Value of Financial Assets and Liabilities for the disclosure impacts. Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement In April 2015, the FASB issued authoritative guidance that clarifies the circumstances under which a cloud computing customer would account for the arrangement as a license of internal-use software. A cloud computing arrangement would include a software license if (1) the customer has a contractual right to take possession of the software at any time during the hosting period without significant penalty and (2) it is feasible for the customer to either operate the software on its own hardware or contract with another party unrelated to the vendor to host the software. If the arrangement does not contain a software license, it would be accounted for as a service contract. The Registrants prospectively adopted the standard in the first quarter of 2016. The adoption of this guidance had no impact on the Registrants' Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. Amendments to the Consolidation Analysis In February 2015, the FASB issued authoritative guidance that amends the consolidation analysis for variable interest entities (VIEs) as well as voting interest entities. The new guidance primarily (1) changes the VIE assessment of limited partnerships, (2) amends the effect that fees paid to a decision maker or service provider have on the VIE analysis, (3) amends how variable interests held by a reporting entity’s related parties and de facto agents impact its consolidation conclusion, (4) clarifies how to determine whether equity holders (as a group) have power over an entity, and (5) provides a scope exception for registered and similar unregistered money market funds. The guidance became effective for the Registrants January 1, 2016. The Registrants adopted the standard in the first quarter of 2016. The Registrants have evaluated the standard and have not identified any changes to consolidation conclusions as a result of the new guidance, but have identified additional entities that are now considered VIEs. See Note 3 - Variable Interest Entities for the disclosure impacts. The following issued accounting standards are not yet required to be reflected in the consolidated financial statements of the Registrants. Revenue from Contracts with Customers In May 2014, the FASB issued authoritative guidance that changes the criteria for recognizing revenue from a contract with a customer. The new standard replaces existing guidance on revenue recognition, including most industry specific guidance, with a five step model for recognizing and measuring revenue from contracts with customers. The objective of the new standard is to provide a single, comprehensive revenue recognition model for all contracts with customers to improve comparability within industries, across industries and across capital markets. The underlying principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. The guidance also requires a number of disclosures regarding the nature, amount, timing and uncertainty of revenue and the related cash flows. The guidance can be applied retrospectively to each prior reporting period presented (full retrospective method) or retrospectively with a cumulative effect adjustment to retained earnings for initial application of the guidance at the date of initial adoption (modified retrospective method). The Registrants are currently assessing the impacts this guidance may have on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures as well as the transition method that they will use to adopt the guidance. Exelon is considering the impacts of the new guidance on its ability to recognize revenue for certain contracts where collectability is in question, its accounting for contributions in aid of construction, bundled sales contracts and contracts with pricing provisions that may require it to recognize revenue at prices other than the contract price (e.g., straight line or estimated future market prices). In addition, the Registrants will be required to capitalize costs to acquire new contracts, whereas Exelon currently expenses those costs as incurred. The guidance is effective for annual reporting periods beginning on or after December 15, 2017, with the option to early adopt the standard for annual periods beginning on or after December 15, 2016. The Registrants do not plan to early adopt the standard. In March 2016, the FASB issued a final amendment to clarify the implementation guidance for principal versus agent considerations and in April 2016 issued a final amendment to clarify the guidance related to identifying performance obligations and the accounting for licenses of intellectual property. The Registrants do not expect significant impacts based on these updates. In May 2016, the FASB issued a final amendment regarding narrow scope improvements and practical expedients. The Registrants are currently assessing the impact of this update. Leases In February 2016, the FASB issued authoritative guidance to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. The guidance requires lessees to recognize both the right-of-use assets and lease liabilities in the balance sheet for most leases, whereas today only financing type lease liabilities (capital leases) are recognized in the balance sheet. This is expected to require significant changes to systems, processes and procedures in order to recognize and measure leases recorded on the balance sheet that are currently classified as operating leases. In addition, the definition of a lease has been revised in regards to when an arrangement conveys the right to control the use of the identified asset under the arrangement which may result in changes to the classification of an arrangement as a lease. The recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee have not significantly changed from current GAAP. The accounting applied by a lessor is largely unchanged from that applied under current GAAP. The standard is effective for fiscal years beginning after December 15, 2018 with early adoption permitted. Lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The Registrants are currently assessing the impacts this guidance may have on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures as well as the potential to early adopt the guidance. Intra-Entity Transfers of Assets Other Than Inventory In October 2016, the FASB issued authoritative guidance which instructs entities to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs (compared to current GAAP which prohibits the recognition of current and deferred income taxes for an intra-entity asset transfer until the asset has been sold to an outside party). The standard is effective for fiscal years beginning after December 15, 2017 with early adoption permitted. The guidance is required to be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The Registrants are currently assessing the impacts this guidance may have on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures as well as the potential to early adopt the guidance. Classification of Certain Cash Receipts and Cash Payments In August 2016, the FASB issued authoritative guidance intended to add or clarify guidance on the classification of certain cash receipts and payments on the statement of cash flows. The new guidance addresses cash flows related to the following: debt prepayment or extinguishment costs, settlement of zero-coupon bonds, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies and bank-owned life insurance policies, distributions received from equity method investees, beneficial interest in securitization transactions, and the application of the predominance principle to separately identifiable cash flows. The standard is effective January 1, 2018, with early adoption permitted. The guidance must be applied on a retrospective basis. The Registrants are currently assessing the impacts this guidance may have on their Consolidated Statements of Cash Flows. Impairment of Financial Instruments In June 2016, the FASB issued authoritative guidance that adds an impairment model to U.S. GAAP called the Current Expected Credit Loss (CECL) model for financial instruments within the scope of the guidance, which includes loans, trade receivables, debt securities classified as held-to-maturity and net investments in leases recognized by a lessor. Under the new guidance, on initial recognition and at each reporting period, an entity would be required to recognize an allowance that reflects the entity’s current estimate of credit losses expected to be incurred over the life of the financial instrument. An entity must consider all available relevant information when estimating expected credit losses. Historical charge-off rates may be used as a starting point for determining expected credit losses; however, the entity must also evaluate how conditions that existed during the historical charge-off period may differ from its current expectations and accordingly revise its estimate of expected credit losses. The standard does not make changes to the existing impairment models for non-financial assets such as fixed assets, intangibles and goodwill. The standard will be effective January 1, 2020. The Registrants are currently assessing the impacts this guidance may have on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. Improvements to Employee Share-Based Payment Accounting In March 2016, the FASB issued authoritative guidance intended to simplify various aspects to how share-based payment awards to employees are accounted for and presented in the financial statements. The new guidance eliminates additional paid-in capital pools and requires excess tax benefits and tax deficiencies to be recorded in the Statement of Operations and Comprehensive Income. The standard is effective for fiscal years beginning after December 15, 2016 with early adoption permitted if all provisions are adopted within the same period. The guidance is required to be applied on either a prospective, modified retrospective, or retrospective basis depending on the provisions applied. The Registrants do not expect that this guidance will have a significant impact on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. The Registrants are currently assessing the potential to early adopt the guidance. Simplifying the Transition to the Equity Method of Accounting In March 2016, the FASB issued authoritative guidance eliminating the requirement to retroactively adopt the equity method of accounting as a result of an increase in the level ownership or degree of influence of an existing investment. The guidance now requires an investor to add the cost of acquiring the additional interest in the investee to the current basis of the investor's previously held interest and adopt the equity method of accounting as of the date the investment becomes qualified for the equity method of accounting. The standard is effective for fiscal years beginning after December 15, 2016 with early adoption permitted. The Registrants do not expect that this guidance will have a significant impact on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. The Registrants are currently assessing the potential to early adopt the guidance. Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships In March 2016, the FASB issued authoritative guidance which clarifies that a change in the counterparty of a derivative contract does not, in and of itself, require dedesignation of that hedge accounting relationship as long as all of the other hedge accounting criteria are met. The standard is effective for fiscal years beginning after December 15, 2016 with early adoption permitted. Entities have the option to adopt this standard on a prospective basis to new derivative contract novations or on a modified retrospective basis. The Registrants do not expect that this guidance will have a significant impact on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. The Registrants are currently assessing the transition method and the potential to early adopt the guidance. Contingent Put and Call Options in Debt Instruments In March 2016, the FASB issued authoritative guidance which simplifies the embedded derivative analysis for debt instruments containing contingent call or put options by removing the requirement to assess whether a contingent event is related to interest rates or credit risks. The guidance clarifies that a contingent put or call option embedded in a debt instrument would be evaluated for possible separate accounting as a derivative instrument without regard to the nature of the exercise contingency. The standard is effective for fiscal years beginning after December 15, 2016 with early adoption permitted. The guidance is required to be applied on a modified retrospective basis to all existing and future debt instruments. The Registrants do not expect that this guidance will have a significant impact on Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures and are currently assessing the potential to early adopt the guidance. Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, the FASB issued authoritative guidance which (i) requires all investments in equity securities, including other ownership interests such as partnerships, unincorporated joint ventures and limited liability companies, to be carried at fair value through net income, (ii) requires an incremental recognition and disclosure requirement related to the presentation of fair value changes of financial liabilities for which the fair value option has been elected, (iii) amends several disclosure requirements, including the methods and significant assumptions used to estimate fair value or a description of the changes in the methods and assumptions used to estimate fair value, and (iv) requires disclosure of the fair value of financial assets and liabilities measured at amortized cost at the amount that would be received to sell the asset or paid to transfer the liability. The standard is effective for fiscal years beginning after December 15, 2017 with early adoption permitted. The guidance is required to be applied retrospectively with a cumulative effect adjustment to retained earnings for initial application of the guidance at the date of adoption (modified retrospective method). The Registrants are currently assessing the impacts this guidance may have on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures as well as the potential to early adopt the guidance. Simplifying the Measurement of Inventory In July 2015, the FASB issued authoritative guidance that requires inventory to be measured at the lower of cost or net realizable value. The new guidance defines net realizable value as the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. This definition is consistent with existing authoritative guidance. Current guidance requires inventory to be measured at the lower of cost or market where market could be replacement cost, net realizable value or net realizable value less an approximately normal profit margin. The guidance is effective for periods beginning after December 15, 2016 with early adoption permitted. The guidance is required to be applied prospectively. The Registrants do not expect that this guidance will have a significant impact on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. The Registrants are currently assessing the potential to early adopt the guidance. Exelon has identified the following new accounting standards that have been recently adopted. Disclosures for Investments in Certain Entities that Calculate Net Asset Value per Share In May 2015, the FASB issued authoritative guidance that removes the requirement to categorize within the fair value hierarchy all investments for which fair value is measured using the net asset value per share practical expedient. Investments measured at net asset value per share using the practical expedient will be presented as a reconciling item between the fair value hierarchy disclosure and the investment line item on the Balance Sheet. The guidance also simplified the disclosure requirements for investments valued using the practical expedient. The guidance is effective for the Registrants for fiscal years beginning after December 15, 2015. The Registrants adopted the standard in the first quarter of 2016, and applied the guidance retrospectively to all prior periods presented. The adoption of this guidance had no impact on the Registrants’ Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income and Consolidated Statements of Cash Flows. See Note 8 - Fair Value of Financial Assets and Liabilities for the disclosure impacts. Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement In April 2015, the FASB issued authoritative guidance that clarifies the circumstances under which a cloud computing customer would account for the arrangement as a license of internal-use software. A cloud computing arrangement would include a software license if (1) the customer has a contractual right to take possession of the software at any time during the hosting period without significant penalty and (2) it is feasible for the customer to either operate the software on its own hardware or contract with another party unrelated to the vendor to host the software. If the arrangement does not contain a software license, it would be accounted for as a service contract. The Registrants prospectively adopted the standard in the first quarter of 2016. The adoption of this guidance had no impact on the Registrants' Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. Amendments to the Consolidation Analysis In February 2015, the FASB issued authoritative guidance that amends the consolidation analysis for variable interest entities (VIEs) as well as voting interest entities. The new guidance primarily (1) changes the VIE assessment of limited partnerships, (2) amends the effect that fees paid to a decision maker or service provider have on the VIE analysis, (3) amends how variable interests held by a reporting entity’s related parties and de facto agents impact its consolidation conclusion, (4) clarifies how to determine whether equity holders (as a group) have power over an entity, and (5) provides a scope exception for registered and similar unregistered money market funds. The guidance became effective for the Registrants January 1, 2016. The Registrants adopted the standard in the first quarter of 2016. The Registrants have evaluated the standard and have not identified any changes to consolidation conclusions as a result of the new guidance, but have identified additional entities that are now considered VIEs. See Note 3 - Variable Interest Entities for the disclosure impacts. The following issued accounting standards are not yet required to be reflected in the consolidated financial statements of the Registrants. Revenue from Contracts with Customers In May 2014, the FASB issued authoritative guidance that changes the criteria for recognizing revenue from a contract with a customer. The new standard replaces existing guidance on revenue recognition, including most industry specific guidance, with a five step model for recognizing and measuring revenue from contracts with customers. The objective of the new standard is to provide a single, comprehensive revenue recognition model for all contracts with customers to improve comparability within industries, across industries and across capital markets. The underlying principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. The guidance also requires a number of disclosures regarding the nature, amount, timing and uncertainty of revenue and the related cash flows. The guidance can be applied retrospectively to each prior reporting period presented (full retrospective method) or retrospectively with a cumulative effect adjustment to retained earnings for initial application of the guidance at the date of initial adoption (modified retrospective method). The Registrants are currently assessing the impacts this guidance may have on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures as well as the transition method that they will use to adopt the guidance. Exelon is considering the impacts of the new guidance on its ability to recognize revenue for certain contracts where collectability is in question, its accounting for contributions in aid of construction, bundled sales contracts and contracts with pricing provisions that may require it to recognize revenue at prices other than the contract price (e.g., straight line or estimated future market prices). In addition, the Registrants will be required to capitalize costs to acquire new contracts, whereas Exelon currently expenses those costs as incurred. The guidance is effective for annual reporting periods beginning on or after December 15, 2017, with the option to early adopt the standard for annual periods beginning on or after December 15, 2016. The Registrants do not plan to early adopt the standard. In March 2016, the FASB issued a final amendment to clarify the implementation guidance for principal versus agent considerations and in April 2016 issued a final amendment to clarify the guidance related to identifying performance obligations and the accounting for licenses of intellectual property. The Registrants do not expect significant impacts based on these updates. In May 2016, the FASB issued a final amendment regarding narrow scope improvements and practical expedients. The Registrants are currently assessing the impact of this update. Leases In February 2016, the FASB issued authoritative guidance to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. The guidance requires lessees to recognize both the right-of-use assets and lease liabilities in the balance sheet for most leases, whereas today only financing type lease liabilities (capital leases) are recognized in the balance sheet. This is expected to require significant changes to systems, processes and procedures in order to recognize and measure leases recorded on the balance sheet that are currently classified as operating leases. In addition, the definition of a lease has been revised in regards to when an arrangement conveys the right to control the use of the identified asset under the arrangement which may result in changes to the classification of an arrangement as a lease. The recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee have not significantly changed from current GAAP. The accounting applied by a lessor is largely unchanged from that applied under current GAAP. The standard is effective for fiscal years beginning after December 15, 2018 with early adoption permitted. Lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The Registrants are currently assessing the impacts this guidance may have on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures as well as the potential to early adopt the guidance. Intra-Entity Transfers of Assets Other Than Inventory In October 2016, the FASB issued authoritative guidance which instructs entities to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs (compared to current GAAP which prohibits the recognition of current and deferred income taxes for an intra-entity asset transfer until the asset has been sold to an outside party). The standard is effective for fiscal years beginning after December 15, 2017 with early adoption permitted. The guidance is required to be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The Registrants are currently assessing the impacts this guidance may have on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures as well as the potential to early adopt the guidance. Classification of Certain Cash Receipts and Cash Payments In August 2016, the FASB issued authoritative guidance intended to add or clarify guidance on the classification of certain cash receipts and payments on the statement of cash flows. The new guidance addresses cash flows related to the following: debt prepayment or extinguishment costs, settlement of zero-coupon bonds, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies and bank-owned life insurance policies, distributions received from equity method investees, beneficial interest in securitization transactions, and the application of the predominance principle to separately identifiable cash flows. The standard is effective January 1, 2018, with early adoption permitted. The guidance must be applied on a retrospective basis. The Registrants are currently assessing the impacts this guidance may have on their Consolidated Statements of Cash Flows. Impairment of Financial Instruments In June 2016, the FASB issued authoritative guidance that adds an impairment model to U.S. GAAP called the Current Expected Credit Loss (CECL) model for financial instruments within the scope of the guidance, which includes loans, trade receivables, debt securities classified as held-to-maturity and net investments in leases recognized by a lessor. Under the new guidance, on initial recognition and at each reporting period, an entity would be required to recognize an allowance that reflects the entity’s current estimate of credit losses expected to be incurred over the life of the financial instrument. An entity must consider all available relevant information when estimating expected credit losses. Historical charge-off rates may be used as a starting point for determining expected credit losses; however, the entity must also evaluate how conditions that existed during the historical charge-off period may differ from its current expectations and accordingly revise its estimate of expected credit losses. The standard does not make changes to the existing impairment models for non-financial assets such as fixed assets, intangibles and goodwill. The standard will be effective January 1, 2020. The Registrants are currently assessing the impacts this guidance may have on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. Improvements to Employee Share-Based Payment Accounting In March 2016, the FASB issued authoritative guidance intended to simplify various aspects to how share-based payment awards to employees are accounted for and presented in the financial statements. The new guidance eliminates additional paid-in capital pools and requires excess tax benefits and tax deficiencies to be recorded in the Statement of Operations and Comprehensive Income. The standard is effective for fiscal years beginning after December 15, 2016 with early adoption permitted if all provisions are adopted within the same period. The guidance is required to be applied on either a prospective, modified retrospective, or retrospective basis depending on the provisions applied. The Registrants do not expect that this guidance will have a significant impact on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. The Registrants are currently assessing the potential to early adopt the guidance. Simplifying the Transition to the Equity Method of Accounting In March 2016, the FASB issued authoritative guidance eliminating the requirement to retroactively adopt the equity method of accounting as a result of an increase in the level ownership or degree of influence of an existing investment. The guidance now requires an investor to add the cost of acquiring the additional interest in the investee to the current basis of the investor's previously held interest and adopt the equity method of accounting as of the date the investment becomes qualified for the equity method of accounting. The standard is effective for fiscal years beginning after December 15, 2016 with early adoption permitted. The Registrants do not expect that this guidance will have a significant impact on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. The Registrants are currently assessing the potential to early adopt the guidance. Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships In March 2016, the FASB issued authoritative guidanc
Fair Value Assets Measured On Recurring Basis Investments Valuation Techniques	t
Fair Value Assets Measured On Recurring Basis Cash And Cash Equivalents Valuation Techniques	Successor Predecessor PHI PHI Pepco Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 Other, net Other, net Other, net Total gains (losses) included in net income $ 1 $ 16 $ 1 $ 1 Change in the unrealized gains (losses) relating to assets and liabilities held — 15 — — Nine Months Ended September 30, 2016 Nine Months Ended September 30, 2015 Pepco Pepco DPL Life Insurance Contracts Life Insurance Contracts Life Insurance Contracts Beginning Balance $ 19 $ 18 $ 1 Total realized / unrealized gains (losses) Included in net income 3 4 — Purchases, sales, issuances and settlements Issuances (1 ) (4 ) — Settlements — — (1 ) Ending Balance $ 21 $ 18 $ — The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities for the period $ 2 $ 2 $ — The following tables present the income statement classification of the total realized and unrealized gains (losses) included in income for Level 3 assets and liabilities measured at fair value on a recurring basis during the three and nine months ended September 30, 2016 and 2015 : Generation Exelon Operating Purchased Other, net (a) Operating Purchased Other, net (a) Total gains (losses) included in net income for the three months ended September 30, 2016 $ 180 $ (85 ) $ (4 ) $ 180 $ (85 ) $ (3 ) Total gains (losses) included in net income for the nine months ended September 30, 2016 (232 ) (107 ) 2 (232 ) (107 ) 4 Change in the unrealized gains (losses) relating to assets and liabilities held for the three months ended September 30, 2016 323 (38 ) 3 323 (38 ) 3 Change in the unrealized gains (losses) relating to assets and liabilities held for the nine months ended September 30, 2016 303 (63 ) 7 303 (63 ) 8 Generation Exelon Operating Revenues Purchased Power and Fuel Other, net (a) Operating Revenues Purchased Power and Fuel Other, net (a) Total gains (losses) included in net income for the three months ended September 30, 2015 $ (4 ) $ (44 ) $ — $ (4 ) $ (44 ) $ — Total gains (losses) included in net income for the nine months ended September 30, 2015 (31 ) (56 ) 4 (31 ) (56 ) 4 Change in the unrealized gains (losses) relating to assets and liabilities held for the three months ended September 30, 2015 198 (17 ) (1 ) 198 (17 ) (1 ) Change in the unrealized gains (losses) relating to assets and liabilities held for the nine months ended September 30, 2015 538 (2 ) 2 538 (2 ) 2 Successor Predecessor PHI PHI Pepco Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 Other, net Other, net Other, net Total gains (losses) included in net income $ 1 $ 16 $ 1 $ 1 Change in the unrealized gains (losses) relating to assets and liabilities held — 15 — — Successor Predecessor PHI PHI Pepco March 24, 2016 to September 30, 2016 January 1, 2016 to March 23, 2016 Nine Months Ended September 30, 2015 Nine Months Ended September 30, 2016 Nine Months Ended September 30, 2015 Other, net Other, net Other, net Total gains (losses) included in net income $ 2 $ (17 ) $ 19 $ 3 $ 4 Change in the unrealized gains (losses) relating to assets and liabilities held 1 1 17 2 2 _________ (a) Other, net activity consists of realized and unrealized gains (losses) included in income for the NDT funds held by Generat
Fair Value Assets Measured On Recurring Basis Nuclear Decommissioning Trust Fund Investments Valuation Techniques	le. As of September 30, 2016 , Generation has outstanding commitments to invest in middle market lending, private equity investments and real estate investments of approximately $170 million , $73 million , and $220 million , respectively. These commitments will be funded by Generation’s existing nuclear decommissioning trust f
Fair Value Assets And Liabilities Measured On Recurring Basis Derivative Financial Instruments Assets And Liabilities Valuation Techniques	3. Mark-to-Market Derivatives (Exelon, Generation, ComEd, PHI and DPL) . Derivative contracts are traded in both exchange-based and non-exchange-based markets. Exchange-based derivatives that are valued using unadjusted quoted prices in active markets are categorized in Level 1 in the fair value hierarchy. Certain derivatives’ pricing is verified using indicative price quotations available through brokers or over-the-counter, on-line exchanges and are categorized in Level 2. These price quotations reflect the average of the bid-ask, mid-point prices and are obtained from sources that the Registrants believe provide the most liquid market for the commodity. The price quotations are reviewed and corroborated to ensure the prices are observable and representative of an orderly transaction between market participants. This includes consideration of actual transaction volumes, market delivery points, bid-ask spreads and contract duration. The remainder of derivative contracts are valued using the Black model, an industry standard option valuation model. The Black model takes into account inputs such as contract terms, including maturity, and market parameters, including assumptions of the future prices of energy, interest rates, volatility, credit worthiness and credit spread. For derivatives that trade in liquid markets, such as generic forwards, swaps and options, model inputs are generally observable. Such instruments are categorized in Level 2. The Registrants’ derivatives are predominately at liquid trading points. For derivatives that trade in less liquid markets with limited pricing information model inputs generally would include both observable and unobservable inputs. These valuations may include an estimated basis adjustment from an illiquid trading point to a liquid trading point for which active price quotations are available. Such instruments are categorized in Level 3. Exelon may utilize fixed-to-floating interest rate swaps, which are typically designated as fair value hedges, as a means to achieve its targeted level of variable-rate debt as a percent of total debt. In addition, the Registrants may utilize interest rate derivatives to lock in interest rate levels in anticipation of future financings. These interest rate derivatives are typically designated as cash flow hedges. Exelon determines the current fair value by calculating the net present value of expected payments and receipts under the swap agreement, based on and discounted by the market's expectation of future interest rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk and other market parameters. As these inputs are based on observable data and valuations of similar instruments, the interest rate swaps are categorized in Level 2 in the fair value hierarchy. See Note 9 - Derivative Financial Instruments for further discussion on mark-to-market derivat
Fair Value Liabilities Measured On Recurring Basis Obligations Valuation Techniques	s
Earnings Per Share, Policy [Policy Text Block]	Diluted earnings per share is calculated by dividing Net income attributable to common shareholders by the weighted average number of shares of common stock outstanding, including shares to be issued upon exercise of stock options, performance share awards and restricted stock outstanding under Exelon’s LTIPs considered to be common stock equivalents.

New Accounting Pronouncements (

New Accounting Pronouncements (Policies)	9 Months Ended
	Sep. 30, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements, Policy [Policy Text Block]	New Accounting Pronouncements (All Registrants) Exelon has identified the following new accounting standards that have been recently adopted. Disclosures for Investments in Certain Entities that Calculate Net Asset Value per Share In May 2015, the FASB issued authoritative guidance that removes the requirement to categorize within the fair value hierarchy all investments for which fair value is measured using the net asset value per share practical expedient. Investments measured at net asset value per share using the practical expedient will be presented as a reconciling item between the fair value hierarchy disclosure and the investment line item on the Balance Sheet. The guidance also simplified the disclosure requirements for investments valued using the practical expedient. The guidance is effective for the Registrants for fiscal years beginning after December 15, 2015. The Registrants adopted the standard in the first quarter of 2016, and applied the guidance retrospectively to all prior periods presented. The adoption of this guidance had no impact on the Registrants’ Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income and Consolidated Statements of Cash Flows. See Note 8 - Fair Value of Financial Assets and Liabilities for the disclosure impacts. Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement In April 2015, the FASB issued authoritative guidance that clarifies the circumstances under which a cloud computing customer would account for the arrangement as a license of internal-use software. A cloud computing arrangement would include a software license if (1) the customer has a contractual right to take possession of the software at any time during the hosting period without significant penalty and (2) it is feasible for the customer to either operate the software on its own hardware or contract with another party unrelated to the vendor to host the software. If the arrangement does not contain a software license, it would be accounted for as a service contract. The Registrants prospectively adopted the standard in the first quarter of 2016. The adoption of this guidance had no impact on the Registrants' Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. Amendments to the Consolidation Analysis In February 2015, the FASB issued authoritative guidance that amends the consolidation analysis for variable interest entities (VIEs) as well as voting interest entities. The new guidance primarily (1) changes the VIE assessment of limited partnerships, (2) amends the effect that fees paid to a decision maker or service provider have on the VIE analysis, (3) amends how variable interests held by a reporting entity’s related parties and de facto agents impact its consolidation conclusion, (4) clarifies how to determine whether equity holders (as a group) have power over an entity, and (5) provides a scope exception for registered and similar unregistered money market funds. The guidance became effective for the Registrants January 1, 2016. The Registrants adopted the standard in the first quarter of 2016. The Registrants have evaluated the standard and have not identified any changes to consolidation conclusions as a result of the new guidance, but have identified additional entities that are now considered VIEs. See Note 3 - Variable Interest Entities for the disclosure impacts. The following issued accounting standards are not yet required to be reflected in the consolidated financial statements of the Registrants. Revenue from Contracts with Customers In May 2014, the FASB issued authoritative guidance that changes the criteria for recognizing revenue from a contract with a customer. The new standard replaces existing guidance on revenue recognition, including most industry specific guidance, with a five step model for recognizing and measuring revenue from contracts with customers. The objective of the new standard is to provide a single, comprehensive revenue recognition model for all contracts with customers to improve comparability within industries, across industries and across capital markets. The underlying principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. The guidance also requires a number of disclosures regarding the nature, amount, timing and uncertainty of revenue and the related cash flows. The guidance can be applied retrospectively to each prior reporting period presented (full retrospective method) or retrospectively with a cumulative effect adjustment to retained earnings for initial application of the guidance at the date of initial adoption (modified retrospective method). The Registrants are currently assessing the impacts this guidance may have on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures as well as the transition method that they will use to adopt the guidance. Exelon is considering the impacts of the new guidance on its ability to recognize revenue for certain contracts where collectability is in question, its accounting for contributions in aid of construction, bundled sales contracts and contracts with pricing provisions that may require it to recognize revenue at prices other than the contract price (e.g., straight line or estimated future market prices). In addition, the Registrants will be required to capitalize costs to acquire new contracts, whereas Exelon currently expenses those costs as incurred. The guidance is effective for annual reporting periods beginning on or after December 15, 2017, with the option to early adopt the standard for annual periods beginning on or after December 15, 2016. The Registrants do not plan to early adopt the standard. In March 2016, the FASB issued a final amendment to clarify the implementation guidance for principal versus agent considerations and in April 2016 issued a final amendment to clarify the guidance related to identifying performance obligations and the accounting for licenses of intellectual property. The Registrants do not expect significant impacts based on these updates. In May 2016, the FASB issued a final amendment regarding narrow scope improvements and practical expedients. The Registrants are currently assessing the impact of this update. Leases In February 2016, the FASB issued authoritative guidance to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. The guidance requires lessees to recognize both the right-of-use assets and lease liabilities in the balance sheet for most leases, whereas today only financing type lease liabilities (capital leases) are recognized in the balance sheet. This is expected to require significant changes to systems, processes and procedures in order to recognize and measure leases recorded on the balance sheet that are currently classified as operating leases. In addition, the definition of a lease has been revised in regards to when an arrangement conveys the right to control the use of the identified asset under the arrangement which may result in changes to the classification of an arrangement as a lease. The recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee have not significantly changed from current GAAP. The accounting applied by a lessor is largely unchanged from that applied under current GAAP. The standard is effective for fiscal years beginning after December 15, 2018 with early adoption permitted. Lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The Registrants are currently assessing the impacts this guidance may have on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures as well as the potential to early adopt the guidance. Intra-Entity Transfers of Assets Other Than Inventory In October 2016, the FASB issued authoritative guidance which instructs entities to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs (compared to current GAAP which prohibits the recognition of current and deferred income taxes for an intra-entity asset transfer until the asset has been sold to an outside party). The standard is effective for fiscal years beginning after December 15, 2017 with early adoption permitted. The guidance is required to be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The Registrants are currently assessing the impacts this guidance may have on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures as well as the potential to early adopt the guidance. Classification of Certain Cash Receipts and Cash Payments In August 2016, the FASB issued authoritative guidance intended to add or clarify guidance on the classification of certain cash receipts and payments on the statement of cash flows. The new guidance addresses cash flows related to the following: debt prepayment or extinguishment costs, settlement of zero-coupon bonds, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies and bank-owned life insurance policies, distributions received from equity method investees, beneficial interest in securitization transactions, and the application of the predominance principle to separately identifiable cash flows. The standard is effective January 1, 2018, with early adoption permitted. The guidance must be applied on a retrospective basis. The Registrants are currently assessing the impacts this guidance may have on their Consolidated Statements of Cash Flows. Impairment of Financial Instruments In June 2016, the FASB issued authoritative guidance that adds an impairment model to U.S. GAAP called the Current Expected Credit Loss (CECL) model for financial instruments within the scope of the guidance, which includes loans, trade receivables, debt securities classified as held-to-maturity and net investments in leases recognized by a lessor. Under the new guidance, on initial recognition and at each reporting period, an entity would be required to recognize an allowance that reflects the entity’s current estimate of credit losses expected to be incurred over the life of the financial instrument. An entity must consider all available relevant information when estimating expected credit losses. Historical charge-off rates may be used as a starting point for determining expected credit losses; however, the entity must also evaluate how conditions that existed during the historical charge-off period may differ from its current expectations and accordingly revise its estimate of expected credit losses. The standard does not make changes to the existing impairment models for non-financial assets such as fixed assets, intangibles and goodwill. The standard will be effective January 1, 2020. The Registrants are currently assessing the impacts this guidance may have on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. Improvements to Employee Share-Based Payment Accounting In March 2016, the FASB issued authoritative guidance intended to simplify various aspects to how share-based payment awards to employees are accounted for and presented in the financial statements. The new guidance eliminates additional paid-in capital pools and requires excess tax benefits and tax deficiencies to be recorded in the Statement of Operations and Comprehensive Income. The standard is effective for fiscal years beginning after December 15, 2016 with early adoption permitted if all provisions are adopted within the same period. The guidance is required to be applied on either a prospective, modified retrospective, or retrospective basis depending on the provisions applied. The Registrants do not expect that this guidance will have a significant impact on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. The Registrants are currently assessing the potential to early adopt the guidance. Simplifying the Transition to the Equity Method of Accounting In March 2016, the FASB issued authoritative guidance eliminating the requirement to retroactively adopt the equity method of accounting as a result of an increase in the level ownership or degree of influence of an existing investment. The guidance now requires an investor to add the cost of acquiring the additional interest in the investee to the current basis of the investor's previously held interest and adopt the equity method of accounting as of the date the investment becomes qualified for the equity method of accounting. The standard is effective for fiscal years beginning after December 15, 2016 with early adoption permitted. The Registrants do not expect that this guidance will have a significant impact on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. The Registrants are currently assessing the potential to early adopt the guidance. Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships In March 2016, the FASB issued authoritative guidance which clarifies that a change in the counterparty of a derivative contract does not, in and of itself, require dedesignation of that hedge accounting relationship as long as all of the other hedge accounting criteria are met. The standard is effective for fiscal years beginning after December 15, 2016 with early adoption permitted. Entities have the option to adopt this standard on a prospective basis to new derivative contract novations or on a modified retrospective basis. The Registrants do not expect that this guidance will have a significant impact on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. The Registrants are currently assessing the transition method and the potential to early adopt the guidance. Contingent Put and Call Options in Debt Instruments In March 2016, the FASB issued authoritative guidance which simplifies the embedded derivative analysis for debt instruments containing contingent call or put options by removing the requirement to assess whether a contingent event is related to interest rates or credit risks. The guidance clarifies that a contingent put or call option embedded in a debt instrument would be evaluated for possible separate accounting as a derivative instrument without regard to the nature of the exercise contingency. The standard is effective for fiscal years beginning after December 15, 2016 with early adoption permitted. The guidance is required to be applied on a modified retrospective basis to all existing and future debt instruments. The Registrants do not expect that this guidance will have a significant impact on Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures and are currently assessing the potential to early adopt the guidance. Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, the FASB issued authoritative guidance which (i) requires all investments in equity securities, including other ownership interests such as partnerships, unincorporated joint ventures and limited liability companies, to be carried at fair value through net income, (ii) requires an incremental recognition and disclosure requirement related to the presentation of fair value changes of financial liabilities for which the fair value option has been elected, (iii) amends several disclosure requirements, including the methods and significant assumptions used to estimate fair value or a description of the changes in the methods and assumptions used to estimate fair value, and (iv) requires disclosure of the fair value of financial assets and liabilities measured at amortized cost at the amount that would be received to sell the asset or paid to transfer the liability. The standard is effective for fiscal years beginning after December 15, 2017 with early adoption permitted. The guidance is required to be applied retrospectively with a cumulative effect adjustment to retained earnings for initial application of the guidance at the date of adoption (modified retrospective method). The Registrants are currently assessing the impacts this guidance may have on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures as well as the potential to early adopt the guidance. Simplifying the Measurement of Inventory In July 2015, the FASB issued authoritative guidance that requires inventory to be measured at the lower of cost or net realizable value. The new guidance defines net realizable value as the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. This definition is consistent with existing authoritative guidance. Current guidance requires inventory to be measured at the lower of cost or market where market could be replacement cost, net realizable value or net realizable value less an approximately normal profit margin. The guidance is effective for periods beginning after December 15, 2016 with early adoption permitted. The guidance is required to be applied prospectively. The Registrants do not expect that this guidance will have a significant impact on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. The Registrants are currently assessing the potential to early adopt the guidance. Exelon has identified the following new accounting standards that have been recently adopted. Disclosures for Investments in Certain Entities that Calculate Net Asset Value per Share In May 2015, the FASB issued authoritative guidance that removes the requirement to categorize within the fair value hierarchy all investments for which fair value is measured using the net asset value per share practical expedient. Investments measured at net asset value per share using the practical expedient will be presented as a reconciling item between the fair value hierarchy disclosure and the investment line item on the Balance Sheet. The guidance also simplified the disclosure requirements for investments valued using the practical expedient. The guidance is effective for the Registrants for fiscal years beginning after December 15, 2015. The Registrants adopted the standard in the first quarter of 2016, and applied the guidance retrospectively to all prior periods presented. The adoption of this guidance had no impact on the Registrants’ Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income and Consolidated Statements of Cash Flows. See Note 8 - Fair Value of Financial Assets and Liabilities for the disclosure impacts. Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement In April 2015, the FASB issued authoritative guidance that clarifies the circumstances under which a cloud computing customer would account for the arrangement as a license of internal-use software. A cloud computing arrangement would include a software license if (1) the customer has a contractual right to take possession of the software at any time during the hosting period without significant penalty and (2) it is feasible for the customer to either operate the software on its own hardware or contract with another party unrelated to the vendor to host the software. If the arrangement does not contain a software license, it would be accounted for as a service contract. The Registrants prospectively adopted the standard in the first quarter of 2016. The adoption of this guidance had no impact on the Registrants' Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. Amendments to the Consolidation Analysis In February 2015, the FASB issued authoritative guidance that amends the consolidation analysis for variable interest entities (VIEs) as well as voting interest entities. The new guidance primarily (1) changes the VIE assessment of limited partnerships, (2) amends the effect that fees paid to a decision maker or service provider have on the VIE analysis, (3) amends how variable interests held by a reporting entity’s related parties and de facto agents impact its consolidation conclusion, (4) clarifies how to determine whether equity holders (as a group) have power over an entity, and (5) provides a scope exception for registered and similar unregistered money market funds. The guidance became effective for the Registrants January 1, 2016. The Registrants adopted the standard in the first quarter of 2016. The Registrants have evaluated the standard and have not identified any changes to consolidation conclusions as a result of the new guidance, but have identified additional entities that are now considered VIEs. See Note 3 - Variable Interest Entities for the disclosure impacts. The following issued accounting standards are not yet required to be reflected in the consolidated financial statements of the Registrants. Revenue from Contracts with Customers In May 2014, the FASB issued authoritative guidance that changes the criteria for recognizing revenue from a contract with a customer. The new standard replaces existing guidance on revenue recognition, including most industry specific guidance, with a five step model for recognizing and measuring revenue from contracts with customers. The objective of the new standard is to provide a single, comprehensive revenue recognition model for all contracts with customers to improve comparability within industries, across industries and across capital markets. The underlying principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. The guidance also requires a number of disclosures regarding the nature, amount, timing and uncertainty of revenue and the related cash flows. The guidance can be applied retrospectively to each prior reporting period presented (full retrospective method) or retrospectively with a cumulative effect adjustment to retained earnings for initial application of the guidance at the date of initial adoption (modified retrospective method). The Registrants are currently assessing the impacts this guidance may have on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures as well as the transition method that they will use to adopt the guidance. Exelon is considering the impacts of the new guidance on its ability to recognize revenue for certain contracts where collectability is in question, its accounting for contributions in aid of construction, bundled sales contracts and contracts with pricing provisions that may require it to recognize revenue at prices other than the contract price (e.g., straight line or estimated future market prices). In addition, the Registrants will be required to capitalize costs to acquire new contracts, whereas Exelon currently expenses those costs as incurred. The guidance is effective for annual reporting periods beginning on or after December 15, 2017, with the option to early adopt the standard for annual periods beginning on or after December 15, 2016. The Registrants do not plan to early adopt the standard. In March 2016, the FASB issued a final amendment to clarify the implementation guidance for principal versus agent considerations and in April 2016 issued a final amendment to clarify the guidance related to identifying performance obligations and the accounting for licenses of intellectual property. The Registrants do not expect significant impacts based on these updates. In May 2016, the FASB issued a final amendment regarding narrow scope improvements and practical expedients. The Registrants are currently assessing the impact of this update. Leases In February 2016, the FASB issued authoritative guidance to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. The guidance requires lessees to recognize both the right-of-use assets and lease liabilities in the balance sheet for most leases, whereas today only financing type lease liabilities (capital leases) are recognized in the balance sheet. This is expected to require significant changes to systems, processes and procedures in order to recognize and measure leases recorded on the balance sheet that are currently classified as operating leases. In addition, the definition of a lease has been revised in regards to when an arrangement conveys the right to control the use of the identified asset under the arrangement which may result in changes to the classification of an arrangement as a lease. The recognition, measurement, and presentation of expenses and cash flows arising from a lease by a lessee have not significantly changed from current GAAP. The accounting applied by a lessor is largely unchanged from that applied under current GAAP. The standard is effective for fiscal years beginning after December 15, 2018 with early adoption permitted. Lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The Registrants are currently assessing the impacts this guidance may have on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures as well as the potential to early adopt the guidance. Intra-Entity Transfers of Assets Other Than Inventory In October 2016, the FASB issued authoritative guidance which instructs entities to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs (compared to current GAAP which prohibits the recognition of current and deferred income taxes for an intra-entity asset transfer until the asset has been sold to an outside party). The standard is effective for fiscal years beginning after December 15, 2017 with early adoption permitted. The guidance is required to be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The Registrants are currently assessing the impacts this guidance may have on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures as well as the potential to early adopt the guidance. Classification of Certain Cash Receipts and Cash Payments In August 2016, the FASB issued authoritative guidance intended to add or clarify guidance on the classification of certain cash receipts and payments on the statement of cash flows. The new guidance addresses cash flows related to the following: debt prepayment or extinguishment costs, settlement of zero-coupon bonds, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies and bank-owned life insurance policies, distributions received from equity method investees, beneficial interest in securitization transactions, and the application of the predominance principle to separately identifiable cash flows. The standard is effective January 1, 2018, with early adoption permitted. The guidance must be applied on a retrospective basis. The Registrants are currently assessing the impacts this guidance may have on their Consolidated Statements of Cash Flows. Impairment of Financial Instruments In June 2016, the FASB issued authoritative guidance that adds an impairment model to U.S. GAAP called the Current Expected Credit Loss (CECL) model for financial instruments within the scope of the guidance, which includes loans, trade receivables, debt securities classified as held-to-maturity and net investments in leases recognized by a lessor. Under the new guidance, on initial recognition and at each reporting period, an entity would be required to recognize an allowance that reflects the entity’s current estimate of credit losses expected to be incurred over the life of the financial instrument. An entity must consider all available relevant information when estimating expected credit losses. Historical charge-off rates may be used as a starting point for determining expected credit losses; however, the entity must also evaluate how conditions that existed during the historical charge-off period may differ from its current expectations and accordingly revise its estimate of expected credit losses. The standard does not make changes to the existing impairment models for non-financial assets such as fixed assets, intangibles and goodwill. The standard will be effective January 1, 2020. The Registrants are currently assessing the impacts this guidance may have on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. Improvements to Employee Share-Based Payment Accounting In March 2016, the FASB issued authoritative guidance intended to simplify various aspects to how share-based payment awards to employees are accounted for and presented in the financial statements. The new guidance eliminates additional paid-in capital pools and requires excess tax benefits and tax deficiencies to be recorded in the Statement of Operations and Comprehensive Income. The standard is effective for fiscal years beginning after December 15, 2016 with early adoption permitted if all provisions are adopted within the same period. The guidance is required to be applied on either a prospective, modified retrospective, or retrospective basis depending on the provisions applied. The Registrants do not expect that this guidance will have a significant impact on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. The Registrants are currently assessing the potential to early adopt the guidance. Simplifying the Transition to the Equity Method of Accounting In March 2016, the FASB issued authoritative guidance eliminating the requirement to retroactively adopt the equity method of accounting as a result of an increase in the level ownership or degree of influence of an existing investment. The guidance now requires an investor to add the cost of acquiring the additional interest in the investee to the current basis of the investor's previously held interest and adopt the equity method of accounting as of the date the investment becomes qualified for the equity method of accounting. The standard is effective for fiscal years beginning after December 15, 2016 with early adoption permitted. The Registrants do not expect that this guidance will have a significant impact on their Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Income, Consolidated Statements of Cash Flows and disclosures. The Registrants are currently assessing the potential to early adopt the guidance. Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships In March 2016, the FASB issued authoritative guidanc

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	9 Months Ended
	Sep. 30, 2016
Variable Interest Entity [Abstract]
Schedule of Variable Interest Entities	The carrying amounts and classification of the consolidated VIEs’ assets and liabilities included in the Registrants' consolidated financial statements at September 30, 2016 and December 31, 2015 are as follows: September 30, 2016 December 31, 2015 Successor Predecessor Exelon (a)(b) Generation BGE PHI (b) ACE Exelon (a) Generation BGE PHI ACE Current assets $ 914 $ 849 $ 44 $ 20 $ 15 $ 909 $ 881 $ 23 $ 12 $ 12 Noncurrent assets 8,235 8,201 3 31 19 8,009 8,004 3 18 18 Total assets $ 9,149 $ 9,050 $ 47 $ 51 $ 34 $ 8,918 $ 8,885 $ 26 $ 30 $ 30 Current liabilities $ 569 $ 439 $ 84 45 $ 40 $ 473 $ 387 $ 81 $ 48 $ 48 Noncurrent liabilities 3,090 2,979 — 111 99 2,927 2,884 41 124 124 Total liabilities $ 3,659 $ 3,418 $ 84 $ 156 $ 139 $ 3,400 $ 3,271 $ 122 $ 172 $ 172 _______ (a) Includes certain purchase accounting adjustments not pushed down to the BGE standalone entity. September 30, 2016 Commercial Agreement VIEs Equity Investment VIEs Total Total assets (a) $ 586 $ 531 $ 1,117 Total liabilities (a) 181 308 489 Exelon's ownership interest in VIE (a) — 193 193 Other ownership interests in VIE (a) 405 34 439 Registrants’ maximum exposure to loss: Carrying amount of equity method investments — 225 225 Contract intangible asset 9 — 9 Debt and payment guarantees — 3 3 Net assets pledged for Zion Station decommissioning (b) 11 — 11 December 31, 2015 Commercial Agreement VIEs Equity Investment VIEs Total Total assets (a) $ 263 $ 164 $ 427 Total liabilities (a) 22 125 147 Exelon's ownership interest in VIE (a) — 11 11 Other ownership interests in VIE (a) 241 28 269 Registrants’ maximum exposure to loss: Carrying amount of equity method investments — 21 21 Contract intangible asset 9 — 9 Debt and payment guarantees — 3 3 Net assets pledged for Zion Station decommissioning (b) 17 — 17 _______ (a) These items represent amounts on the unconsolidated VIE balance sheets, not on Exelon’s or Generation’s Consolidated Balance Sheets. These items are included to provide information regarding the relative size of the unconsolidated VIEs. (b) These items represent amounts on Exelon’s and Generation’s Consolidated Balance Sheets related to the asset sale agreement with ZionSolutions, LLC. The net assets pledged for Zion Station decommissioning includes gross pledged assets of $135 million and $206 million as of September 30, 2016 and December 31, 2015 , respectively; offset by payables to ZionSolutions LLC of $124 million and $189 million as of September 30, 2016 and December 31, 2015 , respectively. These items are included to provide information regarding the relative size of the ZionSolutions LLC unconsolidated VI September 30, 2016 December 31, 2015 Successor Predecessor Exelon (a)(b) Generation BGE PHI (b) ACE Exelon (a) Generation BGE PHI ACE Cash and cash equivalents $ 160 $ 160 $ — $ — $ — $ 164 $ 164 $ — $ — $ — Restricted cash 101 43 44 15 15 100 77 23 12 12 Accounts receivable, net Customer 264 264 — — — 219 219 — — — Other 42 42 — — — 43 43 — — — Mark-to-market derivatives assets 49 49 — — — 140 140 — — — Inventory Materials and supplies 192 192 — — — 181 181 — — — Other current assets 58 51 — 5 — 35 30 — — — Total current assets 866 801 44 20 15 882 854 23 12 12 Property, plant and equipment, net 5,139 5,139 — — — 5,160 5,160 — — — Nuclear decommissioning trust funds 2,173 2,173 — — — 2,036 2,036 — — — Goodwill 47 47 — — — 47 47 — — — Mark-to-market derivatives assets 32 32 — — — 53 53 — — — Other noncurrent assets 257 223 3 31 19 90 85 3 18 18 Total noncurrent assets 7,648 7,614 3 31 19 7,386 7,381 3 18 18 Total assets $ 8,514 $ 8,415 $ 47 $ 51 $ 34 $ 8,268 $ 8,235 $ 26 $ 30 $ 30 Long-term debt due within one year $ 191 $ 64 $ 81 $ 43 $ 38 $ 111 $ 27 $ 79 $ 46 $ 46 Accounts payable 201 201 — — — 216 216 — — — Accrued expenses 102 98 2 2 2 115 113 2 2 2 Mark-to-market derivative liabilities 24 24 — — — 5 5 — — — Unamortized energy contract liabilities 14 14 — — — 12 12 — — — Other current liabilities 34 34 — — — 13 13 — — — Total current liabilities 566 435 83 45 40 472 386 81 48 48 Long-term debt 661 550 — 111 99 666 623 41 124 124 Asset retirement obligations 2,070 2,070 — — — 1,999 1,999 — — — Pension obligation (c) 9 9 — — — 9 9 — — — Unamortized energy contract liabilities 26 26 — — — 39 39 — — — Other noncurrent liabilities 106 106 — — — 79 79 — — — Total noncurrent liabilities 2,872 2,761 — 111 99 2,792 2,749 41 124 124 Total liabilities $ 3,438 $ 3,196 $ 83 $ 156 $ 139 $ 3,264 $ 3,135 $ 122 $ 172 $ 172 _______ (a) Includes certain purchase accounting adjustments not pushed down to the BGE standalone entity. (b) Includes certain purchase accounting adjustments not pushed down to the ACE standalone entity. (c) Includes the CNEG retail gas pension obligation, which is presented as a net asset balance within the Prepaid pension asset line item on Generation’s balance sheet. See Note 13 - Retirement Benefits for additional details.

Mergers, Acquisitions and Dispo

Mergers, Acquisitions and Dispositions (Tables)	9 Months Ended
	Sep. 30, 2016
Business Combinations [Abstract]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustments [Table Text Block]	Three Months Ended Nine Months Ended Year Ended December 31, 2016 (a) 2015 (b) 2016 (a) 2015 (b) 2015 (c) Total operating revenues $ 9,002 $ 8,545 $ 24,468 $ 26,129 $ 33,823 Net income attributable to common shareholders 501 746 1,346 2,169 2,618 Basic earnings per share $ 0.54 $ 0.81 $ 1.46 $ 2.36 $ 2.85 Diluted earnings per share 0.54 0.81 1.45 2.35 2.84 ______________ (a) The amounts above include adjustments for non-recurring costs directly related to the merger of $20 million and $660 million for the three and nine months ended September 30, 2016 , respectively, and intercompany revenue of $171 million for the nine months ended September 30, 2016 . (b) The amounts above include adjustments for non-recurring costs directly related to the merger of $25 million and $100 million and intercompany revenue of $192 million and $426 million for the three and nine months ended September 30, 2015 , respectively. (c) The amounts above include adjustments for non-recurring costs directly related to the merger of $92 million and intercompany revenue of $559 million for the year ended December 31, 2015.
Business Combination, Separately Recognized Transactions [Table Text Block]	Expected Payment Period Successor Description Pepco (a) DPL (a) ACE (a) PHI (a) Exelon (a) Rate credits 2016 - 2017 $ 91 $ 58 $ 101 $ 250 $ 250 Energy efficiency 2016 - 2021 — — — — 120 Charitable contributions 2016 - 2026 28 12 10 50 50 Delivery system modernization Q2 2016 — — — — 22 Green sustainability fund Q2 2016 — — — — 14 Workforce development 2016 - 2020 — — — — 24 Other 7 7 — 14 33 Total $ 126 $ 77 $ 111 $ 314 $ 513 _______ (a) Included within the individual line items is the most favored nation provision estimate of $6 million , $5 million $38 million , $49 million , and $134 million at Pepco, DPL, ACE, PHI and Exelon, respectively. (In millions of dollars, except per share data) Total Consideration Cash paid to PHI shareholders at $27.25 per share (254 million shares outstanding at March 23, 2016) $ 6,933 Cash paid for PHI preferred stock (a) 180 Cash paid for PHI stock-based compensation equity awards (b) 29 Total purchase price $ 7,142 _____________ (a) As of December 31, 2015 , the preferred stock was included in Other non-current assets on Exelon's Consolidated Balance Sheets. (b) PHI’s unvested time-based restricted stock units and performance-based restricted stock units issued prior to April 29, 2014 were immediately vested and paid in cash upon the close of the merger. PHI’s remaining unvested time-based restricted stock units as of the close of the merger were cancelled. There were no remaining unvested performance-based restricted stock units as of the close of the merger.
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	Preliminary Purchase Price Allocation Current assets $ 1,441 Property, plant and equipment 11,088 Regulatory assets 5,015 Other assets 248 Goodwill 4,000 Total assets $ 21,792 Current liabilities $ 2,752 Unamortized energy contracts 1,515 Regulatory liabilities 297 Long-term debt, including current maturities 5,636 Deferred income taxes 3,442 Pension and OPEB liability 821 Other liabilities 187 Total liabilities $ 14,650 Total purchase price $ 7,142
Restructuring and Related Costs	Three Months Ended September 30, Nine Months Ended September 30, Acquisition, Integration and Financing Costs (a) 2016 2015 2016 2015 Exelon (b) $ 20 $ 22 $ 123 $ 84 Generation 9 10 29 30 ComEd (c) — 3 (6 ) 9 PECO 1 1 3 4 BGE (c) 1 2 (3 ) 4 Pepco (c) 3 1 26 3 DPL (c) 2 — 18 2 ACE 2 — 17 1 Successor Predecessor Successor Predecessor Three Months Ended September 30, Three Months Ended September 30, March 24 to September 30, January 1 to March 23, Nine Months Ended September 30, Acquisition, Integration and Financing Costs (a) 2016 2015 2016 2016 2015 PHI (c) $ 7 $ 3 $ 63 $ 29 $ 16 ______________ (a) The costs incurred are classified primarily within Operating and maintenance expense in the Registrants’ respective Consolidated Statements of Operations and Comprehensive Income, with the exception of the financing costs, which are included within Interest expense. Costs do not include merger commitments discussed above. (b) Reflects costs (benefits) recorded at Exelon related to financing, including mark-to-market activity on forward-starting interest rate swaps. Successor Exelon Generation ComEd PECO BGE PHI Pepco (b) DPL (c) ACE Nine Months Ended September 30, 2016 Severance benefits (a) $ 55 $ 9 $ 2 $ 1 $ 1 $ 42 $ 20 $ 12 $ 10 ______________ (a) The amounts above for Generation, ComEd, PECO, BGE, Pepco, DPL and ACE include amounts billed by BSC and/or PHISCO through intercompany allocations of $8 million , $2 million , $1 million , $1 million , $19 million , $11 million and $10 million for the nine months ended September 30, 2016 . For the three and nine months ended September 30, 2016 , the Registrants recorded the following severance costs (benefits) related to the early plant retirements within Operating and maintenance expense in their Consolidated Statements of Operations and Comprehensive Income, pursuant to the authoritative guidance for ongoing severance plans: Exelon Generation (a) Three Months Ended September 30, 2016 $ (2 ) $ (2 ) Nine Months Ended September 30, 2016 $ 44 $ 44 (a) The amounts above for Generation include $2 million for amounts billed by BSC through intercompany allocations for the nine months ended September 30, 2016 . Successor Exelon Generation (a) ComEd (a) PHI Three Months Ended September 30, 2016 $ 8 $ 7 $ — $ 1 September 30, 2015 (3 ) (3 ) — — Nine Months Ended September 30, 2016 $ 12 $ 10 $ 1 $ 1 September 30, 2015 18 17 1 —
Schedule of Goodwill [Table Text Block]	Exelon’s and PHI’s carrying amount of goodwill for the nine months ended September 30, 2016 was as follows: PHI Exelon (a) Beginning balance, December 31, 2015 $ — $ 2,672 Goodwill from business combination 4,016 4,016 Measurement period adjustments (16 ) (16 ) Ending balance, September 30, 2016 $ 4,000 $ 6,672 _____________ (a) As of September 30, 2016 , there were no changes to the carrying amount of goodwill for ComEd, see Note 11 — Intangible Assets of the Exelon 2015 Form 10-K for further information.

Regulatory Matters (Tables)

Regulatory Matters (Tables)	9 Months Ended
	Sep. 30, 2016
Regulated Operations [Abstract]
Schedule of Regulatory Assets	Successor September 30, 2016 Exelon ComEd PECO BGE PHI Pepco DPL ACE Regulatory liabilities Other postretirement benefits $ 85 $ — $ — $ — $ — $ — $ — $ — Nuclear decommissioning 2,704 2,238 466 — — — — — Removal costs 1,627 1,333 — 151 143 20 123 — Deferred rent (q) 40 — — — 40 — — — Energy efficiency and demand response programs 175 135 40 — — — — — DLC program costs 8 — 8 — — — — — Electric distribution tax repairs 79 — 79 — — — — — Gas distribution tax repairs 21 — 21 — — — — — Energy and transmission programs (h)(i)(r)(j)(k)(l) 171 72 59 — 40 17 11 12 Over-recovered revenue decoupling (o) 5 — — 5 — — — — Other 70 3 6 16 45 7 12 24 Total regulatory liabilities 4,985 3,781 679 172 268 44 146 36 Less: current portion 548 204 128 54 101 20 46 35 Total non-current regulatory liabilities $ 4,437 $ 3,577 $ 551 $ 118 $ 167 $ 24 $ 100 $ 1 Predecessor December 31, 2015 Exelon ComEd PECO BGE PHI Pepco DPL ACE Regulatory assets Pension and other postretirement benefits $ 3,156 $ — $ — $ — $ 910 $ — $ — $ — Deferred income taxes (b) 1,616 64 1,473 79 214 137 36 41 AMI programs 399 140 63 196 267 180 87 — Under-recovered distribution service costs (d) 189 189 — — — — — — Debt costs 47 46 1 8 36 19 10 7 Fair value of long-term debt (f) 162 — — — — — — — Severance 9 — — 9 — — — — Asset retirement obligations 108 67 22 19 1 1 — — MGP remediation costs 286 255 30 1 — — — — Under-recovered uncollectible accounts 52 52 — — — — — — Renewable energy 247 247 — — 6 — 1 5 Energy and transmission programs (h)(i)(r)(j)(k)(l) 84 43 1 40 33 9 11 13 Deferred storm costs 2 — — 2 43 19 6 18 Electric generation-related regulatory asset 20 — — 20 — — — — Rate stabilization deferral 87 — — 87 — — — — Energy efficiency and demand response programs 279 — 1 278 401 289 111 1 Merger integration costs 6 — — 6 — — — — Conservation voltage reduction 3 — — 3 — — — — Under-recovered revenue decoupling (o)(p) 30 — — 30 14 10 4 — COPCO acquisition adjustment — — — — — — 13 — Workers compensation and long-term disability costs — — — — 31 31 — — Vacation accrual 6 — 6 — 23 — 14 9 Securitized stranded costs — — — — 202 — — 202 CAP arrearage 7 — 7 — — — — — Removal costs — — — — 369 92 69 208 Other 29 10 13 3 32 14 9 8 Total regulatory assets 6,824 1,113 1,617 781 2,582 801 371 512 Less: current portion 759 218 34 267 305 140 72 98 Total non-current regulatory assets $ 6,065 $ 895 $ 1,583 $ 514 $ 2,277 $ 661 $ 299 $ 414 Predecessor December 31, 2015 Exelon ComEd PECO BGE PHI Pepco DPL ACE Regulatory liabilities Other postretirement benefits $ 94 $ — $ — $ — $ — $ — $ — $ — Nuclear decommissioning 2,577 2,172 405 — — — — — Removal costs 1,527 1,332 — 195 150 21 129 — Energy efficiency and demand response programs 92 52 40 — 1 — — 1 DLC program costs 9 — 9 — — — — — Electric distribution tax repairs 95 — 95 — — — — — Gas distribution tax repairs 28 — 28 — — — — — Energy and transmission programs (h)(i)(r)(j)(k)(l) 131 53 60 18 27 16 19 8 Over-recovered revenue decoupling (o) 1 — — 1 — — — — Other 16 5 2 8 35 7 12 16 Total regulatory liabilities 4,570 3,614 639 222 213 44 160 25 Less: current portion 369 155 112 38 66 15 49 18 Total non-current regulatory liabilities $ 4,201 $ 3,459 $ 527 $ 184 $ 147 $ 29 $ 111 $ 7 ______ (a) As of September 30, 2016 , the pension and other postretirement benefits regulatory asset at Exelon includes regulatory assets of $1,087 million established at the date of the PHI Merger related to unrecognized costs that are probable of regulatory recovery. The regulatory assets are amortized over periods from 3 to 15 years, depending on the underlying component. Pepco, DPL and ACE are currently recovering these costs through base rates. Pepco, DPL and ACE are not earning a return on the recovery of these costs in base rates. (b) As of September 30, 2016 , includes transmission-related regulatory assets that require FERC approval separate from the transmission formula rate of $ 19 million , $32 million , $29 million , $20 million and $18 million for ComEd, BGE, Pepco, DPL and ACE, respectively. As of December 31, 2015 , includes transmission-related regulatory assets that require FERC approval separate from the transmission formula rate of $ 15 million , $ 16 million , $36 million , $18 million and $15 million for ComEd, BGE, Pepco, DPL and ACE, respectively. (c) Represents AMI costs associated with the installation of smart meters and the early retirement of legacy meters throughout the service territories for ComEd, PECO, BGE, Pepco and DPL. An AMI program has not been approved by the NJBPU for ACE in New Jersey. DPL and Pepco have received approval for recovery of deferred AMI program costs from the DCPSC and DPSC in the Delaware and DC service territories, and have requested recovery in pending distribution rate cases with the MDPSC for the Maryland service territories. As of September 30, 2016 , the portion of deferred AMI program costs pending approval from the MDPSC is $32 million for BGE, $134 million for Pepco and $40 million for DPL, of which $75 million for Pepco and $14 million for DPL relates to retired legacy meters which are not earning a return and $3 million of post-test year costs for Pepco which are not earning a return. (d) As of September 30, 2016 , ComEd’s regulatory asset of $232 million was comprised of $178 million for the 2014 - 2016 annual reconciliations and $54 million related to significant one-time events including $24 million of deferred storm costs, $11 million of Constellation and PHI merger and integration related costs and $19 million of smart meter related costs. As of December 31, 2015 , ComEd’s regulatory asset of $189 million was comprised of $142 million for the 2014 and 2015 annual reconciliations and $47 million related to significant one-time events, including $36 million of deferred storm costs and $11 million of Constellation merger and integration related costs. See Note 4 — Merger, Acquisitions, and Dispositions of the Exelon 2015 Form 10-K for further information. (e) Includes at Exelon and PHI the regulatory asset recorded at PHI for debt costs that are recoverable through the ratemaking process at Pepco, DPL, and ACE which were eliminated at Exelon and PHI as part of acquisition accounting. (f) Includes the unamortized regulatory assets recorded for the difference between carrying value and fair value of long-term debt of BGE as of the Constellation merger date and at Exelon and PHI for the difference between carrying value and fair value of long-term debt of Pepco, DPL and ACE as of the PHI Merger date. (g) Represents the regulatory asset recorded at Exelon and PHI offsetting the fair value adjustments related to Pepco's, DPL's and ACE's electricity and natural gas energy supply contracts recorded at PHI as of the PHI Merger date. Pepco, DPL and ACE are allowed full recovery of the costs of these contracts through their respective rate making processes. (h) As of September 30, 2016 , ComEd’s regulatory asset of $31 million included $24 million associated with transmission costs recoverable through its FERC approved formula rate and $7 million of Constellation merger and integration costs to be recovered upon FERC approval. As of September 30, 2016 , ComEd’s regulatory liability of $72 million included $43 million related to over-recovered energy costs and $29 million associated with revenues received for renewable energy requirements. As of December 31, 2015 , ComEd’s regulatory asset of $43 million included $5 million related to under-recovered energy costs, $31 million associated with transmission costs recoverable through its FERC approved formula rate, and $7 million of Constellation merger and integration costs to be recovered upon FERC approval. As of December 31, 2015 , ComEd’s regulatory liability of $53 million included $29 million related to over-recovered energy costs and $24 million associated with revenues received for renewable energy requirements. (i) As of September 30, 2016 , BGE's regulatory asset of $25 million included $3 million of costs associated with transmission costs recoverable through its FERC approved formula rate, $19 million related to under-recovered electric energy costs, $3 million of abandonment costs to be recovered upon FERC approval, and $1 million related to under-recovered natural gas costs. As of December 31, 2015 , BGE’s regulatory asset of $40 million included $12 million of costs associated with transmission costs recoverable through its FERC approved formula rate and $28 million related to under-recovered electric energy costs. As of December 31, 2015 , BGE’s regulatory liability of $18 million related to $14 million of over-recovered transmission costs and $5 million of over-recovered natural gas costs, offset by $1 million of abandonment costs to be recovered upon FERC approval. (j) As of September 30, 2016 , Pepco's regulatory asset of $1 million related to under-recovered electric energy costs. As of September 30, 2016 , Pepco's regulatory liability of $17 million included $9 million of over-recovered transmission costs and $8 million of over-recovered electric energy costs. As of December 31, 2015 , Pepco's regulatory asset of $9 million included $5 million of transmission costs recoverable through its FERC approved formula rate and $4 million of recoverable abandonment costs. As of December 31, 2015 , Pepco's regulatory liability of $16 million included $ 14 million of over-recovered transmission costs and $2 million of over-recovered electric energy costs. (k) As of September 30, 2016 , DPL's regulatory asset of $8 million included $1 million of transmission costs recoverable through its FERC approved formula rate and $7 million of under-recovered electric energy costs. As of September 30, 2016 , DPL's regulatory liability of $11 million included $6 million of over-recovered electric energy costs and $5 million of over-recovered transmission costs. As of December 31, 2015 , DPL's regulatory asset of $11 million included $7 million of transmission costs recoverable through its FERC approved formula rate, $3 million of recoverable abandonment costs, and $1 million of under-recovered electric energy costs. As of December 31, 2015 , DPL's regulatory liability of $19 million included $4 million related to the over-recovered natural gas costs under the GCR mechanism, $4 million of over-recovered electric energy costs, and $11 million of over-recovered transmission costs. (l) As of September 30, 2016 , ACE's regulatory asset of $9 million included $4 million of transmission costs recoverable through its FERC approved formula rate and $5 million of under-recovered electric energy costs. As of September 30, 2016 , ACE's regulatory liability of $12 million included $7 million of over-recovered transmission costs and $5 million of over-recovered electric energy costs. As of December 31, 2015 , ACE's regulatory asset of $13 million included $2 million of transmission costs recoverable through its FERC approved formula rate and $11 million of under-recovered electric energy costs. As of December 31, 2015 , ACE's regulatory liability of $8 million related to over-recovered transmission costs. (m) As of September 30, 2016 , BGE's regulatory asset of $10 million included $6 million of previously incurred PHI acquisition costs as authorized by the June 2016 rate case order. (n) Represents previously incurred PHI acquisition costs expected to be recovered in distribution rates in the Maryland service territories of Pepco and DPL. (o) Represents the electric and natural gas distribution costs recoverable from customers under BGE’s decoupling mechanism. As of September 30, 2016 , BGE had a regulatory liability of $5 million related to over-recovered natural gas revenue decoupling and $0 million related to over-recovered electric revenue decoupling. As of December 31, 2015 , BGE had a regulatory asset of $30 million related to under-recovered electric revenue decoupling and a regulatory liability of $1 million related to over-recovered natural gas revenue decoupling. (p) Represents the electric distribution costs recoverable from customers under Pepco's Maryland and District of Columbia decoupling mechanisms and DPL's Maryland decoupling mechanism. (q) Represents the regulatory liability recorded at Exelon and PHI for deferred rent related to a lease that is recoverable through the ratemaking process at Pepco, DPL and ACE. (r) As of September 30, 2016 , PECO's regulatory liability of $59 million included $30 million related to over-recovered costs under the DSP program, $13 million related to the over-recovered natural gas costs under the PGC, $10 million related to over-recovered non-bypassable transmission service charges and $6 million related to over-recovered electric transmission costs. As of December 31, 2015 , PECO's regulatory asset of $1 million related to under-recovered non-bypassable transmission service charges. As of December 31, 2015 , PECO's regulatory liability of $60 million included $35 million related to over-recovered costs under the DSP program, $22 million related to the over-recovered natural gas costs under the PGC and $3 million related to the over-recovered electric transmission costs.
Schedule of Regulatory Liabilities	Successor September 30, 2016 Exelon ComEd PECO BGE PHI Pepco DPL ACE Regulatory liabilities Other postretirement benefits $ 85 $ — $ — $ — $ — $ — $ — $ — Nuclear decommissioning 2,704 2,238 466 — — — — — Removal costs 1,627 1,333 — 151 143 20 123 — Deferred rent (q) 40 — — — 40 — — — Energy efficiency and demand response programs 175 135 40 — — — — — DLC program costs 8 — 8 — — — — — Electric distribution tax repairs 79 — 79 — — — — — Gas distribution tax repairs 21 — 21 — — — — — Energy and transmission programs (h)(i)(r)(j)(k)(l) 171 72 59 — 40 17 11 12 Over-recovered revenue decoupling (o) 5 — — 5 — — — — Other 70 3 6 16 45 7 12 24 Total regulatory liabilities 4,985 3,781 679 172 268 44 146 36 Less: current portion 548 204 128 54 101 20 46 35 Total non-current regulatory liabilities $ 4,437 $ 3,577 $ 551 $ 118 $ 167 $ 24 $ 100 $ 1 Predecessor December 31, 2015 Exelon ComEd PECO BGE PHI Pepco DPL ACE Regulatory assets Pension and other postretirement benefits $ 3,156 $ — $ — $ — $ 910 $ — $ — $ — Deferred income taxes (b) 1,616 64 1,473 79 214 137 36 41 AMI programs 399 140 63 196 267 180 87 — Under-recovered distribution service costs (d) 189 189 — — — — — — Debt costs 47 46 1 8 36 19 10 7 Fair value of long-term debt (f) 162 — — — — — — — Severance 9 — — 9 — — — — Asset retirement obligations 108 67 22 19 1 1 — — MGP remediation costs 286 255 30 1 — — — — Under-recovered uncollectible accounts 52 52 — — — — — — Renewable energy 247 247 — — 6 — 1 5 Energy and transmission programs (h)(i)(r)(j)(k)(l) 84 43 1 40 33 9 11 13 Deferred storm costs 2 — — 2 43 19 6 18 Electric generation-related regulatory asset 20 — — 20 — — — — Rate stabilization deferral 87 — — 87 — — — — Energy efficiency and demand response programs 279 — 1 278 401 289 111 1 Merger integration costs 6 — — 6 — — — — Conservation voltage reduction 3 — — 3 — — — — Under-recovered revenue decoupling (o)(p) 30 — — 30 14 10 4 — COPCO acquisition adjustment — — — — — — 13 — Workers compensation and long-term disability costs — — — — 31 31 — — Vacation accrual 6 — 6 — 23 — 14 9 Securitized stranded costs — — — — 202 — — 202 CAP arrearage 7 — 7 — — — — — Removal costs — — — — 369 92 69 208 Other 29 10 13 3 32 14 9 8 Total regulatory assets 6,824 1,113 1,617 781 2,582 801 371 512 Less: current portion 759 218 34 267 305 140 72 98 Total non-current regulatory assets $ 6,065 $ 895 $ 1,583 $ 514 $ 2,277 $ 661 $ 299 $ 414 Predecessor December 31, 2015 Exelon ComEd PECO BGE PHI Pepco DPL ACE Regulatory liabilities Other postretirement benefits $ 94 $ — $ — $ — $ — $ — $ — $ — Nuclear decommissioning 2,577 2,172 405 — — — — — Removal costs 1,527 1,332 — 195 150 21 129 — Energy efficiency and demand response programs 92 52 40 — 1 — — 1 DLC program costs 9 — 9 — — — — — Electric distribution tax repairs 95 — 95 — — — — — Gas distribution tax repairs 28 — 28 — — — — — Energy and transmission programs (h)(i)(r)(j)(k)(l) 131 53 60 18 27 16 19 8 Over-recovered revenue decoupling (o) 1 — — 1 — — — — Other 16 5 2 8 35 7 12 16 Total regulatory liabilities 4,570 3,614 639 222 213 44 160 25 Less: current portion 369 155 112 38 66 15 49 18 Total non-current regulatory liabilities $ 4,201 $ 3,459 $ 527 $ 184 $ 147 $ 29 $ 111 $ 7 ______ (a) As of September 30, 2016 , the pension and other postretirement benefits regulatory asset at Exelon includes regulatory assets of $1,087 million established at the date of the PHI Merger related to unrecognized costs that are probable of regulatory recovery. The regulatory assets are amortized over periods from 3 to 15 years, depending on the underlying component. Pepco, DPL and ACE are currently recovering these costs through base rates. Pepco, DPL and ACE are not earning a return on the recovery of these costs in base rates. (b) As of September 30, 2016 , includes transmission-related regulatory assets that require FERC approval separate from the transmission formula rate of $ 19 million , $32 million , $29 million , $20 million and $18 million for ComEd, BGE, Pepco, DPL and ACE, respectively. As of December 31, 2015 , includes transmission-related regulatory assets that require FERC approval separate from the transmission formula rate of $ 15 million , $ 16 million , $36 million , $18 million and $15 million for ComEd, BGE, Pepco, DPL and ACE, respectively. (c) Represents AMI costs associated with the installation of smart meters and the early retirement of legacy meters throughout the service territories for ComEd, PECO, BGE, Pepco and DPL. An AMI program has not been approved by the NJBPU for ACE in New Jersey. DPL and Pepco have received approval for recovery of deferred AMI program costs from the DCPSC and DPSC in the Delaware and DC service territories, and have requested recovery in pending distribution rate cases with the MDPSC for the Maryland service territories. As of September 30, 2016 , the portion of deferred AMI program costs pending approval from the MDPSC is $32 million for BGE, $134 million for Pepco and $40 million for DPL, of which $75 million for Pepco and $14 million for DPL relates to retired legacy meters which are not earning a return and $3 million of post-test year costs for Pepco which are not earning a return. (d) As of September 30, 2016 , ComEd’s regulatory asset of $232 million was comprised of $178 million for the 2014 - 2016 annual reconciliations and $54 million related to significant one-time events including $24 million of deferred storm costs, $11 million of Constellation and PHI merger and integration related costs and $19 million of smart meter related costs. As of December 31, 2015 , ComEd’s regulatory asset of $189 million was comprised of $142 million for the 2014 and 2015 annual reconciliations and $47 million related to significant one-time events, including $36 million of deferred storm costs and $11 million of Constellation merger and integration related costs. See Note 4 — Merger, Acquisitions, and Dispositions of the Exelon 2015 Form 10-K for further information. (e) Includes at Exelon and PHI the regulatory asset recorded at PHI for debt costs that are recoverable through the ratemaking process at Pepco, DPL, and ACE which were eliminated at Exelon and PHI as part of acquisition accounting. (f) Includes the unamortized regulatory assets recorded for the difference between carrying value and fair value of long-term debt of BGE as of the Constellation merger date and at Exelon and PHI for the difference between carrying value and fair value of long-term debt of Pepco, DPL and ACE as of the PHI Merger date. (g) Represents the regulatory asset recorded at Exelon and PHI offsetting the fair value adjustments related to Pepco's, DPL's and ACE's electricity and natural gas energy supply contracts recorded at PHI as of the PHI Merger date. Pepco, DPL and ACE are allowed full recovery of the costs of these contracts through their respective rate making processes. (h) As of September 30, 2016 , ComEd’s regulatory asset of $31 million included $24 million associated with transmission costs recoverable through its FERC approved formula rate and $7 million of Constellation merger and integration costs to be recovered upon FERC approval. As of September 30, 2016 , ComEd’s regulatory liability of $72 million included $43 million related to over-recovered energy costs and $29 million associated with revenues received for renewable energy requirements. As of December 31, 2015 , ComEd’s regulatory asset of $43 million included $5 million related to under-recovered energy costs, $31 million associated with transmission costs recoverable through its FERC approved formula rate, and $7 million of Constellation merger and integration costs to be recovered upon FERC approval. As of December 31, 2015 , ComEd’s regulatory liability of $53 million included $29 million related to over-recovered energy costs and $24 million associated with revenues received for renewable energy requirements. (i) As of September 30, 2016 , BGE's regulatory asset of $25 million included $3 million of costs associated with transmission costs recoverable through its FERC approved formula rate, $19 million related to under-recovered electric energy costs, $3 million of abandonment costs to be recovered upon FERC approval, and $1 million related to under-recovered natural gas costs. As of December 31, 2015 , BGE’s regulatory asset of $40 million included $12 million of costs associated with transmission costs recoverable through its FERC approved formula rate and $28 million related to under-recovered electric energy costs. As of December 31, 2015 , BGE’s regulatory liability of $18 million related to $14 million of over-recovered transmission costs and $5 million of over-recovered natural gas costs, offset by $1 million of abandonment costs to be recovered upon FERC approval. (j) As of September 30, 2016 , Pepco's regulatory asset of $1 million related to under-recovered electric energy costs. As of September 30, 2016 , Pepco's regulatory liability of $17 million included $9 million of over-recovered transmission costs and $8 million of over-recovered electric energy costs. As of December 31, 2015 , Pepco's regulatory asset of $9 million included $5 million of transmission costs recoverable through its FERC approved formula rate and $4 million of recoverable abandonment costs. As of December 31, 2015 , Pepco's regulatory liability of $16 million included $ 14 million of over-recovered transmission costs and $2 million of over-recovered electric energy costs. (k) As of September 30, 2016 , DPL's regulatory asset of $8 million included $1 million of transmission costs recoverable through its FERC approved formula rate and $7 million of under-recovered electric energy costs. As of September 30, 2016 , DPL's regulatory liability of $11 million included $6 million of over-recovered electric energy costs and $5 million of over-recovered transmission costs. As of December 31, 2015 , DPL's regulatory asset of $11 million included $7 million of transmission costs recoverable through its FERC approved formula rate, $3 million of recoverable abandonment costs, and $1 million of under-recovered electric energy costs. As of December 31, 2015 , DPL's regulatory liability of $19 million included $4 million related to the over-recovered natural gas costs under the GCR mechanism, $4 million of over-recovered electric energy costs, and $11 million of over-recovered transmission costs. (l) As of September 30, 2016 , ACE's regulatory asset of $9 million included $4 million of transmission costs recoverable through its FERC approved formula rate and $5 million of under-recovered electric energy costs. As of September 30, 2016 , ACE's regulatory liability of $12 million included $7 million of over-recovered transmission costs and $5 million of over-recovered electric energy costs. As of December 31, 2015 , ACE's regulatory asset of $13 million included $2 million of transmission costs recoverable through its FERC approved formula rate and $11 million of under-recovered electric energy costs. As of December 31, 2015 , ACE's regulatory liability of $8 million related to over-recovered transmission costs. (m) As of September 30, 2016 , BGE's regulatory asset of $10 million included $6 million of previously incurred PHI acquisition costs as authorized by the June 2016 rate case order. (n) Represents previously incurred PHI acquisition costs expected to be recovered in distribution rates in the Maryland service territories of Pepco and DPL. (o) Represents the electric and natural gas distribution costs recoverable from customers under BGE’s decoupling mechanism. As of September 30, 2016 , BGE had a regulatory liability of $5 million related to over-recovered natural gas revenue decoupling and $0 million related to over-recovered electric revenue decoupling. As of December 31, 2015 , BGE had a regulatory asset of $30 million related to under-recovered electric revenue decoupling and a regulatory liability of $1 million related to over-recovered natural gas revenue decoupling. (p) Represents the electric distribution costs recoverable from customers under Pepco's Maryland and District of Columbia decoupling mechanisms and DPL's Maryland decoupling mechanism. (q) Represents the regulatory liability recorded at Exelon and PHI for deferred rent related to a lease that is recoverable through the ratemaking process at Pepco, DPL and ACE. (r) As of September 30, 2016 , PECO's regulatory liability of $59 million included $30 million related to over-recovered costs under the DSP program, $13 million related to the over-recovered natural gas costs under the PGC, $10 million related to over-recovered non-bypassable transmission service charges and $6 million related to over-recovered electric transmission costs. As of December 31, 2015 , PECO's regulatory asset of $1 million related to under-recovered non-bypassable transmission service charges. As of December 31, 2015 , PECO's regulatory liability of $60 million included $35 million related to over-recovered costs under the DSP program, $22 million related to the over-recovered natural gas costs under the PGC and $3 million related to the over-recovered electric transmission costs.
Purchase Of Receivables	Predecessor As of December 31, 2015 Exelon ComEd PECO BGE PHI Pepco DPL ACE Purchased receivables (b)(c) $ 229 $ 103 $ 67 $ 59 $ 100 $ 70 $ 11 $ 19 Allowance for uncollectible accounts (a) (31 ) (16 ) (7 ) (8 ) (6 ) (4 ) — (2 ) Purchased receivables, net $ 198 $ 87 $ 60 $ 51 $ 94 $ 66 $ 11 $ 17 _______ (a) For ComEd, BGE, Pepco and DPL, reflects the incremental allowance for uncollectible accounts recorded, which is in addition to the purchase discount. For ComEd, the incremental uncollectible accounts expense is recovered through its Purchase of Receivables with Consolidated Billing tariff. (b) PECO’s natural gas POR program became effective on January 1, 2012 and included a 1% discount on purchased receivables in order to recover the implementation costs of the program. The implementation costs were fully recovered and the 1% discount was reset to 0%, effective July 2015. (c) Pepco's electric POR program in Maryland included a discount on purchased receivables ranging from 0% to 2% depending on customer class, and Pepco's electric POR program in the District of Columbia included a discount on purchased receivables ranging from 0% to 6% depending on customer class. DPL's electric POR program in Maryland included a discount on purchased receivables ranging from 0% to 1% depending on customer class.
Public Utilities General Disclosures [Table Text Block]	he following total increases/(decreases) were included in ComEd’s, BGE’s, Pepco's, DPL's and ACE's electric transmission formula rate filings: 2016 Annual Transmission Filings (a) ComEd BGE Pepco DPL ACE Initial revenue requirement increase $ 90 $ 12 $ 2 $ 8 $ 8 Annual reconciliation (decrease) increase 4 3 (10 ) (10 ) (14 ) Dedicated facilities (decrease) increase (b) — 13 — — — MAPP abandonment recovery decrease (c) — — (15 ) (12 ) — Total revenue requirement increase (decrease) $ 94 $ 28 $ (23 ) $ (14 ) $ (6 ) Allowed return on rate base (d) 8.47 % 8.09 % 7.88 % 7.21 % 7.83 % Previously authorized allowed return on rate base (d) 8.61 % 8.46 % 8.36 % 7.80 % 8.51 % Allowed ROE (e) 11.50 % 10.50 % 10.50 % 10.50 % 10.50 % _____________ (a) All rates are effective June 2016. (b) BGE's transmission revenues include a FERC approved dedicated facilities charge to recover the costs of providing transmission service to specifically designated load by BGE. (c) In 2012, PJM terminated the MAPP transmission line construction project planned for the Pepco and DPL service territories. Pursuant to a FERC approved settlement agreement, the abandonment costs associated with MAPP were being recovered in transmission rates over a three-year period that ended in May 2016. (d) Refers to the weighted average debt and equity return on transmission rate bases. (e) As part of the FERC-approved settlement of ComEd’s 2007 transmission rate case, the rate of return on common equity is 11.50% and the common equity component of the ratio used to calculate the weighted average debt and equity return for the transmission formula rate is currently capped at 55%. As part of the FERC-approved settlement of the ROE complaint against BGE, Pepco, DPL and ACE, the rate of return on common equity is 10.50% , inclusive of a 50 basis point incentive adder for being a member of a regional transmission organization.

Early Nuclear Plant Retiremen32

Early Nuclear Plant Retirements Early Nuclear Plant Retirements (Tables)	9 Months Ended
	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
ImplicationsofPotentialEarlyPlantRetirement [Table Text Block]	(in millions) TMI Ginna NMP Asset Balances Materials and supplies inventory $ 39 $ 31 $ 70 Nuclear fuel inventory, net 93 41 214 Completed plant, net 956 124 1,151 Construction work in progress 38 13 53 Liability Balances Asset retirement obligation (492 ) (667 ) (780 ) NRC License Renewal Term 2034 2029 2029 (unit 1) 2046 (unit 2)
Incremental Expense Plant Retirement [Table Text Block]
Schedule of Other Operating Cost and Expense, by Component [Table Text Block]	Through September 30, 2016, Exelon's and Generation's results include an incremental $443 million of pre-tax expense for these items as summarized in the table below. Please refer to Note 12 — Nuclear Decommissioning for additional detail on changes to the Nuclear decommissioning ARO balances resulting from the early retirement of Clinton and Quad Cities. Income statement expense (pre-tax) September 30, 2016 Depreciation and Amortization Accelerated depreciation (a) $ 459 Accelerated nuclear fuel amortization 37 Operating and Maintenance Increase ARO accretion, net of contractual offset (b) 2 Contractual offset for ARC depreciation (b) (55 ) Total $ 443 _________ (a) Reflects incremental accelerated depreciation of plant assets, including any ARC. (b) For Quad Cities based on the regulatory agreement with the Illinois Commerce Commission, decommissioning-related activities are offset within Exelon's and Generation's Consolidated Statements of Operations and Comprehensive Income. The offset results in an equal adjustment to the noncurrent payables to ComEd at Generation and an adjustment to the regulatory liabilities at ComEd. Likewise, ComEd has recorded an equal noncurrent affiliate receivable from Generation and corresponding regulatory liability.

Fair Value of Financial Asset33

Fair Value of Financial Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 2016
Fair Value Tables [Line Items]
Fair value of financial liabilities recorded at the carrying amount	The following tables present the carrying amounts and fair values of the Registrants’ short-term liabilities, long-term debt, SNF obligation, trust preferred securities (long-term debt to financing trusts or junior subordinated debentures) and preferred stock as of September 30, 2016 and December 31, 2015 : Exelon September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 567 $ — $ 567 $ — $ 567 Long-term debt (including amounts due within one year) (a) 34,842 1,075 34,272 2,279 37,626 Long-term debt to financing trusts (b) 642 — — 692 692 SNF obligation 1,023 — 856 — 856 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 536 $ 3 $ 533 $ — $ 536 Long-term debt (including amounts due within one year) (a) 25,145 931 23,644 1,349 25,924 Long-term debt to financing trusts (b) 641 — — 673 673 SNF obligation 1,021 — 818 — 818 Generation September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 40 $ — $ 40 $ — $ 40 Long-term debt (including amounts due within one year) (a) 9,255 — 8,015 1,684 9,699 SNF obligation 1,023 — 856 — 856 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 29 $ — $ 29 $ — $ 29 Long-term debt (including amounts due within one year) (a) 8,959 — 7,767 1,349 9,116 SNF obligation 1,021 — 818 — 818 ComEd September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 10 $ — $ 10 $ — $ 10 Long-term debt (including amounts due within one year) (a) 7,031 — 8,081 — 8,081 Long-term debt to financing trusts (b) 205 — — 218 218 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 294 $ — $ 294 $ — $ 294 Long-term debt (including amounts due within one year) (a) 6,509 — 7,069 — 7,069 Long-term debt to financing trusts (b) 205 — — 213 213 PECO September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 2,879 $ — $ 3,266 $ — $ 3,266 Long-term debt to financing trusts 184 — — 207 207 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 2,580 $ — $ 2,786 $ — $ 2,786 Long-term debt to financing trusts 184 — — 195 195 BGE September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 2,662 $ — $ 2,966 $ — $ 2,966 Long-term debt to financing trusts (b) 252 — — 267 267 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 213 $ 3 $ 210 $ — $ 213 Long-term debt (including amounts due within one year) (a) 1,858 — 2,044 — 2,044 Long-term debt to financing trusts (b) 252 — — 264 264 PHI September 30, 2016 Carrying Amount Fair Value Successor Level 1 Level 2 Level 3 Total Short-term liabilities $ 517 $ — $ 517 $ — $ 517 Long-term debt (including amounts due within one year) 6,044 — 5,698 594 6,292 December 31, 2015 Carrying Amount Fair Value Predecessor Level 1 Level 2 Level 3 Total Short-term liabilities $ 958 $ — $ 958 $ — $ 958 Long-term debt (including amounts due within one year) (a) 5,279 — 5,231 586 5,817 Preferred stock 183 — — 183 183 Pepco September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 2,350 $ — $ 3,000 $ 2 $ 3,002 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 64 $ — $ 64 $ — $ 64 Long-term debt (including amounts due within one year) (a) 2,351 — 2,673 — 2,673 DPL September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 17 $ — $ 17 $ — $ 17 Long-term debt (including amounts due within one year) (a) 1,265 — 1,277 101 1,378 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 105 $ — $ 105 $ — $ 105 Long-term debt (including amounts due within one year) (a) 1,265 — 1,185 103 1,288 ACE September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 1,167 $ — $ 1,058 $ 299 $ 1,357 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 5 $ — $ 5 $ — $ 5 Long-term debt (including amounts due within one year) (a) 1,201 — 1,044 280 1,324 ________ (a) Includes unamortized debt issuance costs which are not fair valued of $204 million , $68 million , $47 million , $16 million , $15 million , $30 million , $10 million , and $6 million for Exelon, Generation, ComEd, PECO, BGE, Pepco, DPL and ACE, respectively, as of September 30, 2016 . Includes unamortized debt issuance costs of $180 million , $70 million , $38 million , $15 million , $9 million , $49 million , $31 million , $10 million , and $6 million for Exelon, Generation, ComEd, PECO, BGE, PHI, Pepco, DPL and ACE, respectively, as of December 31, 2015 . (b) Includes unamortized debt issuance costs which are not fair valued of $7 million , $1 million , and $6 million for Exelon, ComEd and BGE, respectively, as of September 30, 2016 and December 31, 2015 .
Assets and liabilities measured and recorded at fair value on recurring basis	PHI, Pepco, DPL and ACE The following tables present assets and liabilities measured and recorded at fair value on PHI's, Pepco's, DPL's and ACE's Consolidated Balance Sheets on a recurring basis and their level within the fair value hierarchy as of September 30, 2016 and December 31, 2015 : Successor Predecessor As of September 30, 2016 As of December 31, 2015 PHI Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents (a) $ 347 $ — $ — $ 347 $ 42 $ — $ — $ 42 Mark-to-market derivative assets (b)(c) 1 — — 1 — — 18 18 Effect of netting and allocation of collateral (1 ) — — (1 ) — — — — Mark-to-market derivative assets subtotal — — — — — — 18 18 Rabbi trust investments Cash equivalents 73 — — 73 12 — — 12 Fixed income — 14 — 14 — 15 — 15 Life insurance contracts — 22 21 43 — 27 19 46 Rabbi trust investments subtotal 73 36 21 130 12 42 19 73 Total assets 420 36 21 477 54 42 37 133 Liabilities Deferred compensation obligation — (28 ) — (28 ) — (30 ) — (30 ) Mark-to-market derivative liabilities (b) — — — — (2 ) — — (2 ) Effect of netting and allocation of collateral — — — — 2 — — 2 Mark-to-market derivative liabilities subtotal — — — — — — — — Total liabilities — (28 ) — (28 ) — (30 ) — (30 ) Total net assets $ 420 $ 8 $ 21 $ 449 $ 54 $ 12 $ 37 $ 103 Pepco DPL ACE As of September 30, 2016 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents (a) $ 127 $ — $ — $ 127 $ — $ — $ — $ — $ 194 $ — $ — $ 194 Mark-to-market derivative assets (b) — — — — 1 — — 1 — — — — Effect of netting and allocation of collateral — — — — (1 ) — — (1 ) — — — — Mark-to-market derivative assets subtotal — — — — — — — — — — — — Rabbi trust investments Cash equivalents 43 — — 43 — — — — — — — — Fixed income — 14 — 14 — — — — — — — — Life insurance contracts — 22 21 43 — — — — — — — — Rabbi trust investments subtotal 43 36 21 100 — — — — — — — — Total assets 170 36 21 227 — — — — 194 — — 194 Liabilities Deferred compensation obligation — (5 ) — (5 ) — (1 ) — (1 ) — — — — Total liabilities — (5 ) — (5 ) — (1 ) — (1 ) — — — — Total net assets (liabilities) $ 170 $ 31 $ 21 $ 222 $ — $ (1 ) $ — $ (1 ) $ 194 $ — $ — $ 194 Pepco DPL ACE As of December 31, 2015 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents $ 2 $ — $ — $ 2 $ — $ — $ — $ — $ 30 $ — $ — $ 30 Rabbi trust investments Cash equivalents 11 — — 11 — — — — — — — — Fixed income — 15 — 15 — — — — — — — — Life insurance contracts — 23 19 42 — — — — — — — — Rabbi trust investments subtotal 11 38 19 68 — — — — — — — — Total assets 13 38 19 70 — — — — 30 — — 30 Liabilities Deferred compensation obligation — (6 ) — (6 ) — (1 ) — (1 ) — — — — Mark-to-market derivative liabilities (b) — — — — (2 ) — — (2 ) — — — — Effect of netting and allocation of collateral — — — — 2 — — 2 — — — — Mark-to-market derivative liabilities subtotal — — — — — — — — — — — — Total liabilities — (6 ) — (6 ) — (1 ) — (1 ) — — — — Total net assets (liabilities) $ 13 $ 32 $ 19 $ 64 $ — $ (1 ) $ — $ (1 ) $ 30 $ — $ — $ 30 _______ (a) PHI excludes cash of $20 million and $16 million at September 30, 2016 and December 31, 2015 and includes long term restricted cash of $19 million and $18 million at September 30, 2016 and December 31, 2015 which is reported in other deferred debits on the balance sheet. Pepco excludes cash of $8 million and $5 million at September 30, 2016 and December 31, 2015 . DPL excludes cash of $4 million and $5 million at September 30, 2016 and December 31, 2015 . ACE excludes cash of $5 million and $3 million at September 30, 2016 and December 31, 2015 and includes long term restricted cash of $19 million and $18 million at September 30, 2016 and December 31, 2015 which is reported in other deferred debits on the balance sheet. (b) Represents natural gas futures purchased by DPL as part of a natural gas hedging program approved by the DPSC. (c) Prior to the PHI Merger, PHI recorded derivative assets for the embedded call and redemption features on the shares of Preferred Stock outstanding as of December 31, 2015. See Note 16 - Mezzanine Equity for additional information. As a result of the PHI Merger, the PHI preferred stock derivative was reduced to zero as of March 23, 2016 . The following tables present assets and liabilities measured and recorded at fair value on Exelon's and Generation’s Consolidated Balance Sheets on a recurring basis and their level within the fair value hierarchy as of September 30, 2016 and December 31, 2015 : Generation Exelon As of September 30, 2016 Level 1 Level 2 Level 3 Not subject to leveling Total Level 1 Level 2 Level 3 Not subject to leveling Total Assets Cash equivalents (a) $ 94 $ — $ — $ — $ 94 $ 1,645 $ — $ — $ — $ 1,645 NDT fund investments Cash equivalents (b) 163 20 — — 183 163 20 — — 183 Equities 3,566 335 — 1,992 5,893 3,566 335 — 1,992 5,893 Fixed income Corporate debt — 1,629 257 — 1,886 — 1,629 257 — 1,886 U.S. Treasury and agencies 1,363 33 — — 1,396 1,363 33 — — 1,396 Foreign governments — 50 — — 50 — 50 — — 50 State and municipal debt — 268 — — 268 — 268 — — 268 Other (c) — 56 — 510 566 — 56 — 510 566 Fixed income subtotal 1,363 2,036 257 510 4,166 1,363 2,036 257 510 4,166 Middle market lending — — 436 23 459 — — 436 23 459 Private equity — — — 138 138 — — — 138 138 Real estate — — — 306 306 — — — 306 306 NDT fund investments subtotal (d) 5,092 2,391 693 2,969 11,145 5,092 2,391 693 2,969 11,145 Pledged assets for Zion Station decommissioning Cash equivalents 14 — — — 14 14 — — — 14 Equities — 1 — — 1 — 1 — — 1 Fixed income U.S. Treasury and agencies 28 2 — — 30 28 2 — — 30 Corporate debt — 3 — — 3 — 3 — — 3 Generation Exelon As of September 30, 2016 Level 1 Level 2 Level 3 Not subject to leveling Total Level 1 Level 2 Level 3 Not subject to leveling Total Fixed income subtotal 28 5 — — 33 28 5 — — 33 Middle market lending — — 19 68 87 — — 19 68 87 Pledged assets for Zion Station (e) 42 6 19 68 135 42 6 19 68 135 Rabbi trust investments Cash equivalents 10 — — — 10 83 — — — 83 Mutual funds 19 — — — 19 50 — — — 50 Fixed income — — — — — — 14 — — 14 Life insurance contracts — 18 — — 18 — 64 21 — 85 Rabbi trust investments subtotal 29 18 — — 47 133 78 21 — 232 Commodity derivative assets Economic hedges 883 2,790 1,948 — 5,621 884 2,790 1,948 — 5,622 Proprietary trading 11 51 36 — 98 11 51 36 — 98 Effect of netting and allocation of collateral (f) (927 ) (2,527 ) (896 ) — (4,350 ) (928 ) (2,527 ) (896 ) — (4,351 ) Commodity derivative assets subtotal (33 ) 314 1,088 — 1,369 (33 ) 314 1,088 — 1,369 Interest rate and foreign currency derivative assets Derivatives designated as hedging instruments — — — — — — 39 — — 39 Economic hedges — 28 — — 28 — 28 — — 28 Proprietary trading 7 1 — — 8 7 1 — — 8 Effect of netting and allocation of collateral (4 ) (17 ) — — (21 ) (4 ) (17 ) — — (21 ) Interest rate and foreign currency derivative assets subtotal 3 12 — — 15 3 51 — — 54 Other investments — — 42 — 42 — — 42 — 42 Total assets 5,227 2,741 1,842 3,037 12,847 6,882 2,840 1,863 3,037 14,622 Liabilities Commodity derivative liabilities Economic hedges (1,037 ) (2,917 ) (1,160 ) — (5,114 ) (1,037 ) (2,917 ) (1,404 ) — (5,358 ) Proprietary trading (10 ) (53 ) (39 ) — (102 ) (10 ) (53 ) (39 ) — (102 ) Effect of netting and allocation of collateral (f) 1,012 2,777 1,046 — 4,835 1,012 2,777 1,046 — 4,835 Commodity derivative liabilities subtotal (35 ) (193 ) (153 ) — (381 ) (35 ) (193 ) (397 ) — (625 ) Interest rate and foreign currency derivative liabilities Derivatives designated as hedging instruments — (18 ) — — (18 ) — (18 ) — — (18 ) Economic hedges — (19 ) — — (19 ) — (19 ) — — (19 ) Proprietary trading (6 ) — — — (6 ) (6 ) — — — (6 ) Effect of netting and allocation of collateral 8 16 — — 24 8 16 — — 24 Interest rate and foreign currency derivative liabilities subtotal 2 (21 ) — — (19 ) 2 (21 ) — — (19 ) Deferred compensation obligation — (32 ) — — (32 ) — (131 ) — — (131 ) Total liabilities (33 ) (246 ) (153 ) — (432 ) (33 ) (345 ) (397 ) — (775 ) Total net assets $ 5,194 $ 2,495 $ 1,689 $ 3,037 $ 12,415 $ 6,849 $ 2,495 $ 1,466 $ 3,037 $ 13,847 Generation Exelon As of December 31, 2015 Level 1 Level 2 Level 3 Not subject to leveling Total Level 1 Level 2 Level 3 Not subject to leveling Total Assets Cash equivalents (a) $ 104 $ — $ — $ — $ 104 $ 5,766 $ — $ — $ — $ 5,766 NDT fund investments Cash equivalents (b) 219 92 — — 311 219 92 — — 311 Equities 3,008 — — 1,894 4,902 3,008 — — 1,894 4,902 Fixed income Corporate debt — 1,824 242 — 2,066 — 1,824 242 — 2,066 U.S. Treasury and agencies 1,323 15 — — 1,338 1,323 15 — — 1,338 Foreign governments — 61 — — 61 — 61 — — 61 State and municipal debt — 326 — — 326 — 326 — — 326 Other (c) — 147 — 390 537 — 147 — 390 537 Fixed income subtotal 1,323 2,373 242 390 4,328 1,323 2,373 242 390 4,328 Middle market lending — — 428 — 428 — — 428 — 428 Private equity — — — 125 125 — — — 125 125 Real estate — — — 35 35 — — — 35 35 Other — — — 216 216 — — — 216 216 NDT fund investments subtotal (d) 4,550 2,465 670 2,660 10,345 4,550 2,465 670 2,660 10,345 Pledged assets for Zion Station decommissioning Cash equivalents — 17 — — 17 — 17 — — 17 Equities 1 5 — — 6 1 5 — — 6 Fixed income U.S. Treasury and agencies 6 2 — — 8 6 2 — — 8 Corporate debt — 46 — — 46 — 46 — — 46 Other — 1 — — 1 — 1 — — 1 Fixed income subtotal 6 49 — — 55 6 49 — — 55 Middle market lending — — 22 105 127 — — 22 105 127 Pledged assets for Zion Station decommissioning subtotal (e) 7 71 22 105 205 7 71 22 105 205 Rabbi trust investments Mutual funds 17 — — — 17 48 — — — 48 Life insurance contracts — 13 — — 13 — 36 — — 36 Rabbi trust investments subtotal 17 13 — — 30 48 36 — — 84 Commodity derivative assets Economic hedges 1,922 3,467 1,707 — 7,096 1,922 3,467 1,707 — 7,096 Proprietary trading 36 64 30 — 130 36 64 30 — 130 Effect of netting and allocation of collateral (f) (1,964 ) (2,629 ) (564 ) — (5,157 ) (1,964 ) (2,629 ) (564 ) — (5,157 ) Commodity derivative assets subtotal (6 ) 902 1,173 — 2,069 (6 ) 902 1,173 — 2,069 Interest rate and foreign currency derivative assets Derivatives designated as hedging instruments — — — — — — 25 — — 25 Economic hedges — 20 — — 20 — 20 — — 20 Proprietary trading 10 5 — — 15 10 5 — — 15 Effect of netting and allocation of collateral (3 ) (3 ) — — (6 ) (3 ) (3 ) — — (6 ) Generation Exelon As of December 31, 2015 Level 1 Level 2 Level 3 Not subject to leveling Total Level 1 Level 2 Level 3 Not subject to leveling Total Interest rate and foreign currency derivative assets subtotal 7 22 — — 29 7 47 — — 54 Other investments — — 33 — 33 — — 33 — 33 Total assets 4,679 3,473 1,898 2,765 12,815 10,372 3,521 1,898 2,765 18,556 Liabilities Commodity derivative liabilities Economic hedges (2,382 ) (3,348 ) (850 ) — (6,580 ) (2,382 ) (3,348 ) (1,097 ) — (6,827 ) Proprietary trading (33 ) (57 ) (37 ) — (127 ) (33 ) (57 ) (37 ) — (127 ) Effect of netting and allocation of collateral (f) 2,440 3,186 765 — 6,391 2,440 3,186 765 — 6,391 Commodity derivative liabilities subtotal 25 (219 ) (122 ) — (316 ) 25 (219 ) (369 ) — (563 ) Interest rate and foreign currency derivative liabilities Derivatives designated as hedging instruments — (16 ) — — (16 ) — (16 ) — — (16 ) Economic hedges — (3 ) — — (3 ) — (3 ) — — (3 ) Proprietary trading (12 ) — — — (12 ) (12 ) — — — (12 ) Effect of netting and allocation of collateral 12 3 — — 15 12 3 — — 15 Interest rate and foreign currency derivative liabilities subtotal — (16 ) — — (16 ) — (16 ) — — (16 ) Deferred compensation obligation — (30 ) — — (30 ) — (99 ) — — (99 ) Total liabilities 25 (265 ) (122 ) — (362 ) 25 (334 ) (369 ) — (678 ) Total net assets $ 4,704 $ 3,208 $ 1,776 $ 2,765 $ 12,453 $ 10,397 $ 3,187 $ 1,529 $ 2,765 $ 17,878 ________ (a) Generation excludes cash of $282 million and $329 million at September 30, 2016 and December 31, 2015 and restricted cash of $161 million and $121 million at September 30, 2016 and December 31, 2015 . Exelon excludes cash of $398 million and $763 million at September 30, 2016 and December 31, 2015 and restricted cash of $197 million and $178 million at September 30, 2016 and December 31, 2015 and includes long term restricted cash of $22 million at September 30, 2016 , which is reported in other deferred debits on the balance sheet. (b) Includes $64 million and $52 million of cash received from outstanding repurchase agreements at September 30, 2016 and December 31, 2015 , respectively, and is offset by an obligation to repay upon settlement of the agreement as discussed in (d) below. (c) Includes derivative instruments of $(10) million and $(8) million , which have a total notional amount of $1,073 million and $1,236 million at September 30, 2016 and December 31, 2015 , respectively. The notional principal amounts for these instruments provide one measure of the transaction volume outstanding as of the periods ended and do not represent the amount of the company's exposure to credit or market loss. (d) Excludes net liabilities of $(69) million and $(3) million at September 30, 2016 and December 31, 2015 , respectively. These items consist of receivables related to pending securities sales, interest and dividend receivables, repurchase agreement obligations, and payables related to pending securities purchases. The repurchase agreements are generally short-term in nature with durations generally of 30 days or less. (e) Excludes net assets of less than $1 million and $1 million at September 30, 2016 and December 31, 2015 , respectively. These items consist of receivables related to pending securities sales, interest and dividend receivables, and payables related to pending securities purchases. (f) Collateral posted to/(received) from counterparties totaled $85 million , $250 million and $150 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of September 30, 2016 . Collateral posted (received) from counterparties, net of collateral paid to counterparties, totaled $476 million , $557 million and $201 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of December 31, 2015 . ComEd, PECO and BGE The following tables present assets and liabilities measured and recorded at fair value on ComEd's, PECO's and BGE's Consolidated Balance Sheets on a recurring basis and their level within the fair value hierarchy as of September 30, 2016 and December 31, 2015 : ComEd PECO BGE As of September 30, 2016 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents (a) $ — $ — $ — $ — $ 521 $ — $ — $ 521 $ 375 $ — $ — $ 375 Rabbi trust investments Mutual funds — — — — 7 — — 7 4 — — 4 Life insurance contracts — — — — — 11 — 11 — — — — Rabbi trust investments subtotal — — — — 7 11 — 18 4 — — 4 Total assets — — — — 528 11 — 539 379 — — 379 Liabilities Deferred compensation obligation — (8 ) — (8 ) — (10 ) — (10 ) — (4 ) — (4 ) Mark-to-market derivative liabilities (b) — — (244 ) (244 ) — — — — — — — — Total liabilities — (8 ) (244 ) (252 ) — (10 ) — (10 ) — (4 ) — (4 ) Total net assets (liabilities) $ — $ (8 ) $ (244 ) $ (252 ) $ 528 $ 1 $ — $ 529 $ 379 $ (4 ) $ — $ 375 ComEd PECO BGE As of December 31, 2015 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets Cash equivalents (a) $ 29 $ — $ — $ 29 $ 271 $ — $ — $ 271 $ 25 $ — $ — $ 25 Rabbi trust investments Mutual funds — — — — 8 — — 8 4 — — 4 Life insurance contracts — — — — — 12 — 12 — — — — Rabbi trust investments subtotal — — — — 8 12 — 20 4 — — 4 Total assets 29 — — 29 279 12 — 291 29 — — 29 Liabilities Deferred compensation obligation — (8 ) — (8 ) — (12 ) — (12 ) — (4 ) — (4 ) Mark-to-market derivative liabilities (b) — — (247 ) (247 ) — — — — — — — — Total liabilities — (8 ) (247 ) (255 ) — (12 ) — (12 ) — (4 ) — (4 ) Total net assets (liabilities) $ 29 $ (8 ) $ (247 ) $ (226 ) $ 279 $ — $ — $ 279 $ 29 $ (4 ) $ — $ 25 _________ (a) ComEd excludes cash of $44 million and $38 million at September 30, 2016 and December 31, 2015 and restricted cash of $2 million and $2 million at September 30, 2016 and December 31, 2015 . PECO excludes cash of $27 million and $27 million at September 30, 2016 and December 31, 2015 and $1 million of restricted cash at September 30, 2016 . BGE excludes cash of $13 million and $6 million at September 30, 2016 and December 31, 2015 and restricted cash of $2 million and $2 million at September 30, 2016 and December 31, 2015 and includes long term restricted cash of $3 million at September 30, 2016 , which is reported in other deferred debits on the balance sheet. (b) The Level 3 balance consists of the current and noncurrent liability of $19 million and $225 million , respectively, at September 30, 2016 , and $23 million and $224 million , respectively, at December 31, 2015 , related to floating-to-fixed energy swap contracts with unaffiliated suppliers.
Fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis	March 23, 2016 . The following tables present the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis during the three and nine months ended September 30, 2016 and 2015 : Successor Generation ComEd PHI Exelon Three Months Ended September 30, 2016 NDT Fund Investments Pledged Assets for Zion Station Decommissioning Mark-to-Market Derivatives Other Investments Total Generation Mark-to-Market Derivatives (a) Life Insurance Contracts Eliminated in Consolidation Total Balance as of June 30, 2016 $ 715 $ 25 $ 609 $ 37 $ 1,386 $ (221 ) $ 20 $ — $ 1,185 Total realized / unrealized gains (losses) Included in net income (4 ) — 95 (b) 1 92 — 1 — 93 Included in noncurrent payables to affiliates 6 — — — 6 — — (6 ) — Included in payable for Zion Station decommissioning — (1 ) — — (1 ) — — — (1 ) Included in regulatory assets — — — — — (23 ) — 6 (17 ) Change in collateral — — 31 — 31 — — — 31 Purchases, sales, issuances and settlements Purchases 4 — 207 (d) 3 214 — — — 214 Sales — (5 ) (2 ) — (7 ) — — — (7 ) Issuances — — — — — — — — — Settlements (28 ) — — — (28 ) — — — (28 ) Transfers into Level 3 — — (1 ) 1 — — — — — Transfers out of Level 3 — — (4 ) — (4 ) — — — (4 ) Balance at September 30, 2016 $ 693 $ 19 $ 935 $ 42 $ 1,689 $ (244 ) $ 21 $ — $ 1,466 The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of September 30, 2016 $ 3 $ — $ 285 $ — $ 288 $ — $ — $ — $ 288 Successor Generation ComEd PHI (c) Exelon Nine Months Ended September 30, 2016 NDT Fund Investments Pledged Assets for Zion Station Decommissioning Mark-to-Market Derivatives Other Investments Total Generation Mark-to-Market Derivatives (a) Life Insurance Contracts Eliminated in Consolidation Total Balance as of December 31, 2015 $ 670 $ 22 $ 1,051 $ 33 $ 1,776 $ (247 ) $ — $ — $ 1,529 Included due to merger — — — — — — — 20 — 20 Total realized / unrealized gains (losses) Included in net income 2 — (339 ) (b) 1 (336 ) — 2 — (334 ) Included in noncurrent payables to affiliates 18 — — — 18 — — (18 ) — Included in payable for Zion Station decommissioning — 1 — — 1 — — — 1 Included in regulatory assets/liabilities — — — — — 3 — 18 21 Change in collateral — — (51 ) — (51 ) — — — (51 ) Purchases, sales, issuances and settlements Purchases 123 1 289 (d) 7 420 — — — 420 Sales (1 ) (5 ) (5 ) — (11 ) — — — (11 ) Issuances — — — — — — (1 ) — (1 ) Settlements (119 ) — — — (119 ) — — — (119 ) Transfers into Level 3 — — 1 1 2 — — — 2 Transfers out of Level 3 — — (11 ) — (11 ) — — — (11 ) Balance as of September 30, 2016 $ 693 $ 19 $ 935 $ 42 $ 1,689 $ (244 ) $ 21 $ — $ 1,466 The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of September 30, 2016 $ 7 $ — $ 240 $ — $ 247 $ — $ 1 $ — $ 248 ___________________ (a) Includes $25 million of decreases in fair value and realized losses due to settlements of $2 million recorded in purchased power expense associated with floating-to-fixed energy swap contracts with unaffiliated suppliers for the three months ended September 30, 2016 . Includes $ 10 million of decreases in fair value and realized losses due to settlements of $ 13 million for the nine months ended September 30, 2016 . (b) Includes a reduction for the reclassification of $190 million and $579 million of realized gains due to the settlement of derivative contracts recorded in results of operations for the three and nine months ended September 30, 2016 , respectively. (c) Successor period represents activity from March 24, 2016 through September 30, 2016 . See tables below for PHI's predecessor periods, as well as activity for Pepco and DPL for the three and nine months ended September 30, 2016 . (d) Includes $168 million of fair value from contracts acquired as a result of portfolio acquisitions. Generation ComEd Exelon Three Months Ended September 30, 2015 NDT Fund Investments Pledged Assets for Zion Station Decommissioning Mark-to-Market Derivatives Other Investments Total Generation Mark-to-Market Derivatives (a) Eliminated in Consolidation Total Balance as of June 30, 2015 $ 667 $ 41 $ 1,021 $ 30 $ 1,759 $ (223 ) $ — $ 1,536 Total realized / unrealized gains (losses) — Included in net income — — (48 ) (b) — (48 ) — — (48 ) Included in noncurrent payables to affiliates — — — — — — — — Included in payable for Zion Station decommissioning — 1 — — 1 — — 1 Included in regulatory assets — — — — — (20 ) — (20 ) Change in collateral — — 90 — 90 — — 90 Purchases, sales, issuances and settlements Purchases 15 — 50 2 67 — — 67 Sales — (13 ) (5 ) — (18 ) — — (18 ) Settlements (13 ) — — — (13 ) — — (13 ) Transfers into Level 3 — — 69 — 69 — — 69 Transfers out of Level 3 — — (3 ) — (3 ) — — (3 ) Balance as of September 30, 2015 $ 669 $ 29 $ 1,174 $ 32 $ 1,904 $ (243 ) $ — $ 1,661 The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of September 30, 2015 $ (1 ) $ — $ 181 $ — $ 180 $ — $ — $ 180 Generation ComEd Exelon Nine Months Ended September 30, 2015 NDT Fund Investments Pledged Assets for Zion Station Decommissioning Mark-to-Market Derivatives Other Investments Total Generation Mark-to-Market Derivatives (a) Eliminated in Consolidation Total Balance as of December 31, 2014 $ 605 $ 50 $ 1,050 $ 3 $ 1,708 $ (207 ) $ — $ 1,501 Total realized / unrealized gains (losses) Included in net income 4 — (87 ) (b) — (83 ) — — (83 ) Included in noncurrent payables to affiliates 17 — — — 17 — (17 ) — Included in payable for Zion Station decommissioning — 2 — — 2 — — 2 Included in regulatory assets — — — — — (36 ) 17 (19 ) Change in collateral — — 72 — 72 — — 72 Purchases, sales, issuances and settlements Purchases 122 1 107 29 259 — — 259 Sales (8 ) (24 ) (10 ) — (42 ) — — (42 ) Settlements (75 ) — — — (75 ) — — (75 ) Transfers into Level 3 4 — 80 — 84 — — 84 Transfers out of Level 3 — — (38 ) — (38 ) — — (38 ) Balance as of September 30, 2015 $ 669 $ 29 $ 1,174 $ 32 $ 1,904 $ (243 ) $ — $ 1,661 The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of September 30, 2015 $ 2 $ — $ 536 $ — $ 538 $ — $ — $ 538 _________ (a) Includes $19 million of decreases in fair value and a reduction for realized gains due to settlements of $1 million recorded in purchased power expense associated with floating-to-fixed energy swap contracts with unaffiliated suppliers for the three months ended September 30, 2015 . Includes $44 million of decreases in fair value and an increase for realized losses due to settlements of $8 million for the nine months ended September 30, 2015 . (b) Includes a reduction for the reclassification of $229 million and $623 million of realized gains due to the settlement of derivative contracts recorded in results of operations for the three and nine months ended September 30, 2015 , respectiv
Total realized and unrealized gains (losses) included in income for Level 3 assets and liabilities measured at fair value on a recurring basis
Fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis, valuation technique	isk. The table below discloses the significant inputs to the forward curve used to value these positions. Type of trade Fair Value at September 30, 2016 Valuation Technique Unobservable Input Range Mark-to-market derivatives — Economic Hedges (Exelon and Generation) (a)(c) $ 788 Discounted Forward power $6 - $130 Forward gas $1.24 - $9.53 Option Model Volatility 5% - 115% Mark-to-market derivatives — Proprietary trading (Exelon and Generation) (a)(c) $ (3 ) Discounted Forward power $15 - $68 Mark-to-market derivatives (Exelon and ComEd) $ (244 ) Discounted Forward heat (b) 8x - 9x Marketability 3% - 8% Renewable 86% - 121% _________ (a) The valuation techniques, unobservable inputs and ranges are the same for the asset and liability positions. (b) Quoted forward natural gas rates are utilized to project the forward power curve for the delivery of energy at specified future dates. The natural gas curve is extrapolated beyond its observable period to the end of the contract’s delivery. (c) The fair values do not include cash collateral posted on level three positions of $150 million as of September 30, 2016 . Type of trade Fair Value at December 31, 2015 Valuation Technique Unobservable Input Range Mark-to-market derivatives — Economic Hedges (Exelon and Generation) (a)(c) $ 857 Discounted Forward power price $11 - $88 Forward gas price $1.18 - $8.95 Option Model Volatility percentage 5% - 152% Mark-to-market derivatives — Proprietary trading (Exelon and Generation) (a)(c) $ (7 ) Discounted Forward power price $13 - $78 Mark-to-market derivatives (Exelon and ComEd) $ (247 ) Discounted Cash Flow Forward heat (b) 9x - 10x Marketability reserve 3.5% - 7% Renewable factor 87% - 128% _________ (a) The valuation techniques, unobservable inputs and ranges are the same for the asset and liability positions. (b) Quoted forward natural gas rates are utilized to project the forward power curve for the delivery of energy at specified future dates. The natural gas curve is extrapolated beyond its observable period to the end of the contract’s delivery. (c) The fair values do not include cash collateral posted on level three positions of $201 million as of
Exelon Generation Co L L C [Member]
Fair Value Tables [Line Items]
Fair value of financial liabilities recorded at the carrying amount	Generation September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 40 $ — $ 40 $ — $ 40 Long-term debt (including amounts due within one year) (a) 9,255 — 8,015 1,684 9,699 SNF obligation 1,023 — 856 — 856 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 29 $ — $ 29 $ — $ 29 Long-term debt (including amounts due within one year) (a) 8,959 — 7,767 1,349 9,116 SNF obligation 1,021 — 818 — 818
Commonwealth Edison Co [Member]
Fair Value Tables [Line Items]
Fair value of financial liabilities recorded at the carrying amount	ComEd September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 10 $ — $ 10 $ — $ 10 Long-term debt (including amounts due within one year) (a) 7,031 — 8,081 — 8,081 Long-term debt to financing trusts (b) 205 — — 218 218 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 294 $ — $ 294 $ — $ 294 Long-term debt (including amounts due within one year) (a) 6,509 — 7,069 — 7,069 Long-term debt to financing trusts (b) 205 — — 213 213
PECO Energy Co [Member]
Fair Value Tables [Line Items]
Fair value of financial liabilities recorded at the carrying amount	PECO September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 2,879 $ — $ 3,266 $ — $ 3,266 Long-term debt to financing trusts 184 — — 207 207 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 2,580 $ — $ 2,786 $ — $ 2,786 Long-term debt to financing trusts 184 — — 195 195
Baltimore Gas and Electric Company [Member]
Fair Value Tables [Line Items]
Fair value of financial liabilities recorded at the carrying amount	BGE September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 2,662 $ — $ 2,966 $ — $ 2,966 Long-term debt to financing trusts (b) 252 — — 267 267 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 213 $ 3 $ 210 $ — $ 213 Long-term debt (including amounts due within one year) (a) 1,858 — 2,044 — 2,044 Long-term debt to financing trusts (b) 252 — — 264 264
PEPCO Holdings Inc [Member]
Fair Value Tables [Line Items]
Fair value of financial liabilities recorded at the carrying amount	PHI September 30, 2016 Carrying Amount Fair Value Successor Level 1 Level 2 Level 3 Total Short-term liabilities $ 517 $ — $ 517 $ — $ 517 Long-term debt (including amounts due within one year) 6,044 — 5,698 594 6,292 December 31, 2015 Carrying Amount Fair Value Predecessor Level 1 Level 2 Level 3 Total Short-term liabilities $ 958 $ — $ 958 $ — $ 958 Long-term debt (including amounts due within one year) (a) 5,279 — 5,231 586 5,817 Preferred stock 183 — — 183 183
Potomac Electric Power Company [Member]
Fair Value Tables [Line Items]
Fair value of financial liabilities recorded at the carrying amount	Pepco September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 2,350 $ — $ 3,000 $ 2 $ 3,002 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 64 $ — $ 64 $ — $ 64 Long-term debt (including amounts due within one year) (a) 2,351 — 2,673 — 2,673
Delmarva Power and Light Company [Member]
Fair Value Tables [Line Items]
Fair value of financial liabilities recorded at the carrying amount	DPL September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 17 $ — $ 17 $ — $ 17 Long-term debt (including amounts due within one year) (a) 1,265 — 1,277 101 1,378 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 105 $ — $ 105 $ — $ 105 Long-term debt (including amounts due within one year) (a) 1,265 — 1,185 103 1,288
Atlantic City Electric Company [Member]
Fair Value Tables [Line Items]
Fair value of financial liabilities recorded at the carrying amount	ACE September 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 1,167 $ — $ 1,058 $ 299 $ 1,357 December 31, 2015 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 5 $ — $ 5 $ — $ 5 Long-term debt (including amounts due within one year) (a) 1,201 — 1,044 280 1,324

Derivative Financial Instrume34

Derivative Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of the derivative fair value	September 30, 2016 . Generation Exelon Corporate Exelon Description Derivatives Designated as Hedging Instruments Economic Hedges Proprietary Trading (a) Collateral and Netting (b) Subtotal Derivatives Designated as Hedging Instruments Total Mark-to-market derivative assets (current assets) $ — $ 15 $ 4 $ (10 ) $ 9 $ — $ 9 Mark-to-market derivative assets (noncurrent assets) — 13 4 (11 ) 6 39 45 Total mark-to-market derivative assets — 28 8 (21 ) 15 39 54 Mark-to-market derivative liabilities (current liabilities) (8 ) (10 ) (3 ) 12 (9 ) — (9 ) Mark-to-market derivative liabilities (noncurrent liabilities) (10 ) (9 ) (3 ) 12 (10 ) — (10 ) Total mark-to-market derivative liabilities (18 ) (19 ) (6 ) 24 (19 ) — (19 ) Total mark-to-market derivative net assets (liabilities) $ (18 ) $ 9 $ 2 $ 3 $ (4 ) $ 39 $ 35 _________ (a) Generation enters into interest rate derivative contracts to economically hedge risk associated with the interest rate component of commodity positions. The characterization of the interest rate derivative contracts between the proprietary trading activity in the above table is driven by the corresponding characterization of the underlying commodity position that gives rise to the interest rate exposure. Generation does not utilize proprietary trading interest rate derivatives with the objective of benefiting from shifts or changes in market interest rates. (b) Exelon and Generation net all available amounts allowed under the derivative accounting guidance on the balance sheet. These amounts include unrealized derivative transactions with the same counterparty under legally enforceable master netting agreements and cash collateral. In some cases Exelon and Generation may have other offsetting exposures, subject to a master netting or similar agreement, such as accrued interest, transactions that do not qualify as derivatives, letters of credit and other forms of non-cash collateral. These are not reflected in the table above. The following table provides a summary of the interest rate and foreign exchange hedge balances recorded by the Registrants as of December 31, 2015 : Generation Exelon Corporate Exelon Description Derivatives Designated as Hedging Instruments Economic Hedges Proprietary Trading (a) Collateral and Netting (b) Subtotal Derivatives Designated as Hedging Instruments Total Mark-to-market derivative assets (current assets) $ — $ 10 $ 10 $ (5 ) $ 15 $ — $ 15 Mark-to-market derivative assets (noncurrent assets) — 10 5 (1 ) 14 25 39 Total mark-to-market derivative assets — 20 15 (6 ) 29 25 54 Mark-to-market derivative liabilities (current liabilities) (8 ) (2 ) (9 ) 11 (8 ) — (8 ) Mark-to-market derivative liabilities (noncurrent liabilities) (8 ) (1 ) (3 ) 4 (8 ) — (8 ) Total mark-to-market derivative liabilities (16 ) (3 ) (12 ) 15 (16 ) — (16 ) Total mark-to-market derivative net assets (liabilities) $ (16 ) $ 17 $ 3 $ 9 $ 13 $ 25 $ 38 __________ (a) Generation enters into interest rate derivative contracts to economically hedge risk associated with the interest rate component of commodity positions. The characterization of the interest rate derivative contracts between the proprietary trading activity in the above table is driven by the corresponding characterization of the underlying commodity position that gives rise to the interest rate exposure. Generation does not utilize proprietary trading interest rate derivatives with the objective of benefiting from shifts or changes in market interest rates. (b) The following table provides a summary of the derivative fair value balances recorded by the Registrants as of September 30, 2016 : Successor Generation ComEd DPL PHI Exelon Derivatives Economic Hedges Proprietary Trading Collateral and Netting (a) Subtotal (b) Economic Hedges (c) Economic Hedges (d) Collateral and Netting (a) Subtotal Subtotal Total Derivatives Mark-to-market derivative assets (current assets) $ 3,482 $ 67 $ (2,804 ) $ 745 $ — $ 1 $ (1 ) $ — $ — $ 745 Mark-to-market derivative assets (noncurrent assets) 2,139 31 (1,546 ) 624 — — — — — 624 Total mark-to-market derivative assets 5,621 98 (4,350 ) 1,369 — 1 (1 ) — — 1,369 Mark-to-market derivative liabilities (current liabilities) (3,229 ) (61 ) 3,096 (194 ) (19 ) — — — — (213 ) Mark-to-market derivative liabilities (noncurrent liabilities) (1,885 ) (41 ) 1,739 (187 ) (225 ) — — — — (412 ) Total mark-to-market derivative liabilities (5,114 ) (102 ) 4,835 (381 ) (244 ) — — — — (625 ) Total mark-to-market derivative net assets (liabilities) $ 507 $ (4 ) $ 485 $ 988 $ (244 ) $ 1 $ (1 ) $ — $ — $ 744 ______ (a) Exelon, Generation, PHI and DPL net all available amounts allowed under the derivative accounting guidance on the balance sheet. These amounts include unrealized derivative transactions with the same counterparty under legally enforceable master netting agreements and cash collateral. In some cases Exelon and Generation may have other offsetting exposures, subject to a master netting or similar agreement, such as trade receivables and payables, transactions that do not qualify as derivatives, letters of credit and other forms of non-cash collateral. These are not reflected in the table above. (b) Current and noncurrent assets are shown net of collateral of $135 million and $84 million , respectively, and current and noncurrent liabilities are shown net of collateral of $156 million and $110 million , respectively. The total cash collateral posted, net of cash collateral received and offset against mark-to-market assets and liabilities was $485 million at September 30, 2016 . (c) Includes current and noncurrent liabilities relating to floating-to-fixed energy swap contracts with unaffiliated suppliers. (d) Represents natural gas futures purchased by DPL as part of a natural gas hedging program approved by the DPSC. The following table provides a summary of the derivative fair value balances recorded by the Registrants as of December 31, 2015 : Predecessor Generation ComEd Exelon DPL PHI Corporate PHI Description Economic Hedges Proprietary Trading Collateral and Netting (a) Subtotal (b) Economic Hedges (c) Total Economic Hedges (e) Collateral and Netting (a) Subtotal Other (d) Total Mark-to-market derivative assets (current assets) $ 5,236 $ 108 $ (3,994 ) $ 1,350 $ — $ 1,350 $ — $ — $ — $ 18 $ 18 Mark-to-market derivative assets (noncurrent assets) 1,860 22 (1,163 ) 719 — 719 — — — — — Total mark-to-market derivative assets 7,096 130 (5,157 ) 2,069 — 2,069 — — — 18 18 Mark-to-market derivative liabilities (current liabilities) (4,907 ) (94 ) 4,827 (174 ) (23 ) (197 ) (2 ) 2 — — — Mark-to-market derivative liabilities (noncurrent liabilities) (1,673 ) (33 ) 1,564 (142 ) (224 ) (366 ) — — — — — Total mark-to-market derivative liabilities (6,580 ) (127 ) 6,391 (316 ) (247 ) (563 ) (2 ) 2 — — — Total mark-to-market derivative net assets (liabilities) $ 516 $ 3 $ 1,234 $ 1,753 $ (247 ) $ 1,506 $ (2 ) $ 2 $ — $ 18 $ 18 ________ (a) Exelon, Generation, PHI and DPL net all available amounts allowed under the derivative accounting guidance on the balance sheet. These amounts include unrealized derivative transactions with the same counterparty under legally enforceable master netting agreements and cash collateral. In some cases Exelon and Generation may have other offsetting exposures, subject to a master netting or similar agreement, such as trade receivables and payables, transactions that do not qualify as derivatives, and letters of credit and other forms of non-cash collateral. These are not reflected in the table above. (b) Current and noncurrent assets are shown net of collateral of $352 million and $180 million , respectively, and current and noncurrent liabilities are shown net of collateral of $480 million and $222 million , respectively. The total cash collateral posted, net of cash collateral received and offset against mark-to-market assets and liabilities was $1,234 million at December 31, 2015 . (c) Includes current and noncurrent liabilities relating to floating-to-fixed energy swap contracts with unaffiliated suppliers. Exelon includes the gain or loss on the hedged items and the offsetting loss or gain on the related interest rate swaps in interest expense as follows: Three Months Ended September 30, Income Statement Location 2016 2015 2016 2015 Gain (loss) on Swaps Gain (loss) on Borrowings Exelon Interest expense $ (8 ) $ 16 $ 14 $ (13 ) Nine Months Ended September 30, Income Statement Location 2016 2015 2016 2015 Gain (loss) on Swaps Gain (loss) on Borrowings Generation Interest expense (a) $ — $ (1 ) $ — $ — Exelon Interest expense 15 15 (3 ) (4 ) __________ (a) For the nine months ended September 30, 2015 , the loss on Generation swaps included $1 million realized in earnings with an immaterial amount excluded from hedge effectiveness testing.
The activity of accumulated OCI related to cash flow hedges	amounts reclassified from AOCI, when combined with the impacts of the hedged transactions, result in the ultimate recognition of net revenues or expenses at the contractual price. Total Cash Flow Hedge OCI Activity, Net of Income Tax Generation Exelon Three Months Ended September 30, 2016 Income Statement Location Total Cash Total Cash Flow Hedges AOCI derivative loss at June 30, 2016 $ (25 ) $ (26 ) Effective portion of changes in fair value 1 3 AOCI derivative loss at September 30, 2016 $ (24 ) $ (23 ) Total Cash Flow Hedge OCI Activity, Net of Income Tax Generation Exelon Nine Months Ended September 30, 2016 Income Statement Location Total Cash Total Cash Accumulated OCI derivative loss at December 31, 2015 $ (21 ) $ (19 ) Effective portion of changes in fair value — (1 ) Reclassifications from AOCI to net income Interest Expense (3 ) (a) (3 ) (a) Accumulated OCI derivative loss at September 30, 2016 $ (24 ) $ (23 ) Total Cash Flow Hedge OCI Activity, Net of Income Tax Generation Exelon Three Months Ended September 30, 2015 Income Statement Location Total Cash Total Cash Flow Hedges AOCI derivative loss at June 30, 2015 (21 ) $ (19 ) Effective portion of changes in fair value (7 ) (8 ) Reclassifications from AOCI to net income Interest Expense 3 3 AOCI derivative loss at September 30, 2015 $ (25 ) $ (24 ) Total Cash Flow Hedge OCI Activity, Net of Income Tax Generation Exelon Nine Months Ended September 30, 2015 Income Statement Location Total Cash Total Cash Flow Hedges Accumulated OCI derivative loss at December 31, 2014 $ (18 ) $ (28 ) Effective portion of changes in fair value (13 ) (18 ) Reclassifications from AOCI to net income Other, net — 16 (b) Reclassifications from AOCI to net income Interest Expense 8 8 Reclassifications from AOCI to net income Operating Revenues (2 ) (2 ) Accumulated OCI derivative loss at September 30, 2015 $ (25 ) $ (24 ) __
Other Derivatives - Gain (loss) and reclassification	Generation Exelon Nine Months Ended September 30, 2016 Operating Revenues Purchased Power and Fuel Total Total Change in fair value of commodity positions $ 127 $ 36 $ 163 $ 163 Reclassification to realized at settlement of commodity positions (484 ) 217 (267 ) (267 ) Net commodity mark-to-market gains (losses) (357 ) 253 (104 ) (104 ) Change in fair value of treasury positions (3 ) — (3 ) (3 ) Reclassification to realized at settlement of treasury positions (6 ) — (6 ) (6 ) Net treasury mark-to-market gains (losses) (9 ) — (9 ) (9 ) Net mark-to-market gains (losses) $ (366 ) $ 253 $ (113 ) $ (113 ) Generation Exelon Corporate Exelon Three Months Ended September 30, 2015 Operating Revenues Purchased Power and Fuel Total Interest Total Change in fair value of commodity positions $ 136 $ (178 ) $ (42 ) $ — $ (42 ) Reclassification to realized at settlement of commodity positions (143 ) 46 (97 ) (97 ) Net commodity mark-to-market gains (losses) (7 ) (132 ) (139 ) — (139 ) Change in fair value of treasury positions 2 — 2 — 2 Reclassification to realized at settlement of treasury positions (2 ) — (2 ) — (2 ) Net treasury mark-to-market gains (losses) — — — — — Net mark-to-market gains (losses) $ (7 ) $ (132 ) $ (139 ) $ — $ (139 ) Generation Exelon Corporate Exelon Nine Months Ended September 30, 2015 Operating Revenues Purchased Power and Fuel Total Interest Total Change in fair value of commodity positions $ 513 $ (163 ) $ 350 $ — $ 350 Reclassification to realized at settlement of commodity positions (347 ) 249 (98 ) — (98 ) Net commodity mark-to-market gains (losses) 166 86 252 — 252 Change in fair value of treasury positions 12 — 12 36 48 Reclassification to realized at settlement of treasury positions (6 ) — (6 ) 64 58 Net treasury mark-to-market gains (losses) 6 — 6 100 106 Net mark-to-market gains (losses) $ 172 $ 86 $ 258 $ 100 $ 358 Prop the tables below, “Change in fair value” represents the change in fair value of the derivative contracts held at the reporting date. The “Reclassification to realized at settlement” represents the recognized change in fair value that was reclassified to realized due to settlement of the derivative during the period. Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 Change in fair value of commodity positions $ 4 $ (4 ) $ 18 $ 5 Reclassification to realized at settlement of commodity positions (6 ) (2 ) (17 ) (8 ) Net commodity mark-to-market gains (losses) (2 ) (6 ) 1 (3 ) Change in fair value of treasury positions — 3 (2 ) 7 Reclassification to realized at settlement of treasury positions 1 (3 ) 2 (9 ) Net treasury mark-to-market gains (losses) 1 — — (2 ) Total net mark-to-market gains (losses) $ (1 ) $ (6 ) $ 1 $ (5 ) Cr
Schedule of Derivative Instruments [Table Text Block]	e
Information on Generation's credit exposure for all derivative instruments, normal purchase normal sales, and applicable payables and receivables, net of collateral and instruments that are subject to master netting agreements	following tables provide information on Generation’s credit exposure for all derivative instruments, NPNS and applicable payables and receivables, net of collateral and instruments that are subject to master netting agreements, as of September 30, 2016 . The tables further delineate that exposure by credit rating of the counterparties and provide guidance on the concentration of credit risk to individual counterparties. The figures in the tables below exclude credit risk exposure from individual retail counterparties, Nuclear fuel procurement contracts and exposure through RTOs, ISOs, NYMEX, ICE and Nodal commodity exchanges, further discussed in ITEM 3. — QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK. Additionally, the figures in the tables below exclude exposures with affiliates, including net receivables with ComEd, PECO, BGE, Pepco, DPL and ACE of $24 million , $45 million , $22 million , $47 million , $12 million , and $10 million as of September 30, 2016 , respectively. Rating as of September 30, 2016 Total Exposure Before Credit Collateral Credit Collateral (a) Net Exposure Number of Counterparties Greater than 10% of Net Exposure Net Exposure of Counterparties Greater than 10% of Net Exposure Investment grade $ 1,017 $ 4 $ 1,013 1 $ 355 Non-investment grade 175 22 153 — — No external ratings Internally rated — investment grade 423 3 420 — — Internally rated — non-investment grade 61 3 58 — — Total $ 1,676 $ 32 $ 1,644 1 $ 355 Net Credit Exposure by Type of Counterparty As of September 30, 2016 Financial institutions $ 117 Investor-owned utilities, marketers, power producers 757 Energy cooperatives and municipalities 712 Other 58 Total $ 1,644 _____ (a) As of September 30, 2016 , credit collateral held from counterparties where Generation had credit exposure included $10 million of cash and $22 million of letters of credit. The credit collateral does not include non-liquid collateral. aggregate fair value of all derivative instruments with credit-risk-related contingent features in a liability position that are not fully collateralized (excluding transactions on the exchanges that are fully collateralized) is detailed in the table below: Credit-Risk Related Contingent Feature September 30, 2016 December 31, 2015 Gross Fair Value of Derivative Contracts Containing this Feature (a) $ (975 ) $ (932 ) Offsetting Fair Value of In-the-Money Contracts Under Master Netting Arrangements (b) 664 684 Net Fair Value of Derivative Contracts Containing This Feature (c) $ (311 ) $ (248 ) _______ (a) Amount represents the gross fair value of out-of-the-money derivative contracts containing credit-risk related contingent features ignoring the effects of master netting agreements. (b) Amount represents the offsetting fair value of in-the-money derivative contracts under legally enforceable master netting agreements with the same counterparty, which reduces the amount of any liability for which a Registrant could potentially be required to post collateral. (c) Amount represents the net fair value of out-of-the-money derivative contracts containing credit-risk related contingent features after considering the mitigating effects of offsetting positions under master netting arrangements and reflects the actual net liability upon which any potential contingent collateral obligations would be based. Ge

Debt and Credit Agreements (Tab

Debt and Credit Agreements (Tables)	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Schedule of Short-term Debt	Commercial Paper Borrowings September 30, 2016 December 31, 2015 ComEd $ 10 $ 294 BGE — 210 PHI Corporate — 484 Pepco — 64 DPL 17 105 ACE — 5
Schedule Of Issuance Of Long Term Debt	During the nine months ended September 30, 2016 , the following long-term debt was issued: Company Type Interest Rate Maturity Amount Use of Proceeds Exelon Corporate Senior Unsecured Notes 2.45 % April 15, 2021 $ 300 Repay commercial paper issued by PHI and for general corporate purposes Exelon Corporate Senior Unsecured Notes 3.40 % April 15, 2026 $ 750 Repay commercial paper issued by PHI and for general corporate purposes Exelon Corporate Senior Unsecured Notes 4.45 % April 15, 2046 $ 750 Repay commercial paper issued by PHI and for general corporate purposes Generation Renewable Power Generation Nonrecourse Debt 4.11 % March 31, 2035 $ 150 Paydown long term debt obligations at Sacramento PV Energy and Constellation Solar Horizons and for general corporate purposes Generation Albany Green Energy Project Financing LIBOR + 1.25% November 17, 2017 $ 86 Albany Green Energy biomass generation development Generation Energy Efficiency Project Financing 3.17 % December 31, 2017 $ 16 Funding to install energy conservation measures in Brooklyn, NY Generation Energy Efficiency Project Financing 3.42 % January 31, 2018 $ 13 Funding to install energy conservation measures for the Naval Station Great Lakes project ComEd First Mortgage Bonds, Series 120 2.55 % June 15, 2026 $ 500 Refinance maturing mortgage bonds, repay a portion of ComEd's outstanding commercial paper obligations and for general corporate purposes ComEd First Mortgage Bonds, Series 121 3.65 % June 15, 2046 $ 700 Refinance maturing mortgage bonds, repay a portion of ComEd's outstanding commercial paper obligations and for general corporate purposes Generation Energy Efficiency Project Financing 3.52 % April 30, 2018 $ 11 Funding to install energy conservation measures for the Smithsonian Zoo project Pepco Energy Efficiency Project Financing 3.30 % December 15, 2017 $ 2 Funding to install energy conservation measures for the DOE Germantown project BGE Notes 2.40 % August 15, 2026 $ 350 Redeem the $190M of outstanding preference shares and for general corporate purposes BGE Notes 3.50 % August 15, 2046 $ 500 Redeem the $190M of outstanding preference shares and for general corporate purposes PECO (a) First Mortgage Bonds 1.70 % September 15, 2021 $ 300 Refinance maturing mortgage bonds Generation SolGen Nonrecourse Debt 3.93 % September 30, 2036 $ 150 General corporate purposes Generation ExGen Texas Power Nonrecourse Debt LIBOR + 4.25% September 18, 2019 $ 4 General corporate purposes for EGTP
Retirement and Redemptions of Current and Long-Term Debt

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	Three Months Ended September 30, 2016 Successor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE U.S. Federal statutory rate 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% Increase (decrease) due to: State income taxes, net of Federal income tax benefit 3.8 2.6 7.3 2.4 5.2 5.6 5.6 5.2 6.1 Qualified nuclear decommissioning trust fund income 4.0 7.8 — — — — — — — Domestic production activities deduction — — — — — — — — — Health care reform legislation — — — — — — — — — Amortization of investment tax credit, net deferred taxes (0.9) (1.6) (0.6) (0.1) (0.2) (0.1) — (0.2) (0.1) Plant basis differences (3.0) — (1.9) (6.7) (0.5) (5.0) (6.7) (1.3) (4.6) Production tax credits and other credits (2.9) (5.7) (0.1) — — — — — — Noncontrolling interests 0.2 0.5 — — — — — — — Statute of limitations expiration (0.1) 0.3 — — — — — — — Penalties 4.3 — 27.2 — — — — — — Merger expenses (0.6) — — — — (5.7) (2.3) (8.6) (2.9) Other (0.8) (0.5) 0.1 0.1 (0.4) (0.7) (0.9) 0.1 (0.6) Effective income tax rate 39.0% 38.4% 67.0% 30.7% 39.1% 29.1% 30.7% 30.2% 32.9% Three Months Ended September 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE U.S. Federal statutory rate 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% Increase (decrease) due to: State income taxes, net of Federal income tax benefit 2.7 2.1 5.0 1.2 5.3 6.2 4.8 7.4 5.4 Qualified nuclear decommissioning trust fund income (5.4) (12.5) — — — — — — — Domestic production activities deduction (4.9) (11.6) — — — — — — — Health care reform legislation — — — — 0.2 — — — — Amortization of investment tax credit, net deferred taxes (2.3) (5.2) (0.3) (0.1) (0.2) (0.2) (0.1) (0.6) (0.3) Plant basis differences (1.4) — (0.1) (7.0) (0.6) (3.7) (3.5) (3.5) (3.1) Production tax credits and other credits (3.8) (9.0) — — — (1.2) — — — Noncontrolling interests 1.7 3.9 — — — — — — — Statute of limitations expiration (6.4) (15.2) — — — — — — — Other 1.2 0.4 0.3 — (0.4) (1.1) (1.4) (0.8) 1.9 Effective income tax rate 16.4% (12.1)% 39.9% 29.1% 39.3% 35.0% 34.8% 37.5% 38.9% Successor Predecessor Nine Months Ended September 30, 2016 March 24, 2016 to September 30, 2016 January 1, 2016 to March 23, 2016 Exelon Generation ComEd PECO BGE Pepco DPL (a) ACE (a) PHI (a) PHI U.S. Federal statutory rate 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% Increase (decrease) due to: State income taxes, net of Federal income tax benefit (b) 2.5 2.6 5.4 1.3 4.8 23.0 310.5 5.5 4.4 11.9 Qualified nuclear decommissioning trust fund income 4.8 8.8 — — — — — — — — Domestic production activities deduction — — — — — — — — — — Health care reform legislation — — — — — — — — — — Amortization of investment tax credit, including deferred taxes on basis difference (1.3) (2.0) (0.3) (0.1) (0.2) (0.2) (17.9) 0.5 0.5 (0.9) Plant basis differences (4.5) — (0.6) (8.8) (3.3) (29.0) (98.6) 7.8 17.5 (13.5) Production tax credits and other credits (4.1) (7.6) — — — — — — — — Noncontrolling interests 0.5 0.9 — — — — — — — — Statute of limitations expiration (0.5) (1.7) — — — — — — — Penalties 2.3 — 5.6 — — — — — — Merger expenses 6.2 — — — — 36.7 635.9 (35.4) (49.8) 11.1 Other (c) (1.8) (2.1) — (1.5) — (2.5) 35.1 0.4 1.4 3.6 Effective income tax rate 39.1% 33.9% 45.1% 25.9% 36.3% 63.0% 900.0% 13.8% 9.0% 47.2% Nine Months Ended September 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE U.S. Federal statutory rate 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% 35.0% Increase (decrease) due to: State income taxes, net of Federal income tax benefit 3.1 2.8 5.2 1.2 5.3 7.1 4.6 6.1 5.5 Qualified nuclear decommissioning trust fund income (0.9) (1.6) — — — — — — — Domestic production activities deduction (2.8) (4.9) — — — — — — — Health care reform legislation — — — — 0.2 — — — — Amortization of investment tax credit, including deferred taxes on basis difference (1.2) (1.9) (0.3) (0.1) (0.1) (0.3) (0.1) (0.4) (0.5) Plant basis differences (1.2) — (0.1) (7.3) (0.4) (5.0) (6.2) (2.0) (2.5) Production tax credits and other credits (2.2) (3.8) — — — (1.9) — — — Noncontrolling interests — 0.1 — — — — — — — Statute of limitations expiration (1.6) (2.9) — — — — — — — Other 0.9 0.6 0.2 0.2 (0.1) (0.1) (0.7) (0.5) 0.8 Effective income tax rate 29.1% 23.4% 40.0% 29.0% 39.9% 34.8% 32.6% 38.2% 38.3%

Nuclear Decommissioning (Tables

Nuclear Decommissioning (Tables) - Exelon Generation Co L L C [Member]	9 Months Ended
	Sep. 30, 2016
Schedule Of Nuclear Decommissioning [Line Items]
Nuclear decommissioning asset retirement obligation rollforward	The following table provides a rollforward of the nuclear decommissioning ARO reflected on Exelon’s and Generation’s Consolidated Balance Sheets from December 31, 2015 to September 30, 2016 : Nuclear decommissioning ARO at December 31, 2015 (a) $ 8,246 Accretion expense 325 Net increase due to changes in, and timing of, estimated cash flows 444 Costs incurred to decommission retired plants (6 ) Nuclear decommissioning ARO at September 30, 2016 (a) $ 9,009 _________ (a) Includes $44 million and $7 million for the current portion of the ARO at September 30, 2016 and December 31, 2015 , respectively, which is included in Other current liabilities on Exelon’s and Generation’s Consolidated Balance Sheets.
Unrealized Gains (Losses) on nuclear decommissioning trust funds	The following table provides unrealized gains on NDT funds for the three and nine months ended September 30, 2016 and 2015 : Exelon and Generation Exelon and Generation Three Months Ended September 30, Nine Months Ended 2016 2015 2016 2015 Net unrealized gains (losses) on decommissioning trust funds — Regulatory Agreement Units (a) $ 155 $ (301 ) $ 286 $ (385 ) Net unrealized gains (losses) on decommissioning trust funds — Non-Regulatory Agreement Units (b)(c) 116 (218 ) 216 (274 ) _________ (a) Net unrealized gains related to Generation’s NDT funds associated with Regulatory Agreement Units are included in Regulatory liabilities on Exelon’s Consolidated Balance Sheets and Noncurrent payables to affiliates on Generation’s Consolidated Balance Sheets. (b) Excludes $(5) million of net unrealized gain related to the Zion Station pledged assets for the three months ended September 30, 2016 . Excludes $(2) million and $9 million of net unrealized gain related to the Zion Station pledged assets for the nine months ended September 30, 2016 and 2015 , respectively. Net unrealized gains related to Zion Station pledged assets are included in the Payable for Zion Station decommissioning on Exelon’s and Generation’s Consolidated Balance Sheets. (c) Net unrealized gains related to Generation’s NDT funds with Non-Regulatory Agreement Units are included within Other, net in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income.
Zion Station pledged assets	September 30, 2016 and December 31, 2015 : Exelon and Generation September 30, 2016 December 31, 2015 Carrying value of Zion Station pledged assets $ 135 $ 206 Payable to Zion Solutions (a) 124 189 Current portion of payable to Zion Solutions (b) 91 99 Cumulative withdrawals by Zion Solutions to pay decommissioning costs (c) 855 786 _________ (a) Excludes a liability recorded within Exelon’s and Generation’s Consolidated Balance Sheets related to the tax obligation on the unrealized activity associated with the Zion Station NDT funds. The NDT funds will be utilized to satisfy the tax obligations as gains and losses are realized. (b) Included in Other current liabilities within Exelon’s and Generation’s Consolidated Balance Sheets. (c) Includes project expenses to decommission Zion Station and estimated tax payments on Zion Station NDT fund earnings.

Retirement Benefits (Tables)

Retirement Benefits (Tables)	9 Months Ended
	Sep. 30, 2016
Compensation and Retirement Disclosure [Abstract]
Schedule Of Pension And Other Postretirement Benefit Costs	The amounts below represent Exelon's, Generation's, ComEd's, PECO's, BGE's, PHI's, Pepco's, DPL's, ACE's, BSC's and PHISCO's allocated portion of the pension and postretirement benefit plan costs, which were included in Property, plant and equipment within the respective Consolidated Balance Sheets and Operating and maintenance expense within the Consolidated Statement of Operations and Comprehensive Income during the three and nine months ended September 30, 2016 and 2015 . Three Months Ended September 30, Nine Months Ended September 30, Pension and Other Postretirement Benefit Costs 2016 2015 2016 2015 Exelon $ 161 $ 159 $ 458 $ 476 Generation 54 67 163 200 ComEd 41 52 124 155 PECO 8 10 25 29 BGE 17 16 51 49 BSC (a) 13 14 37 43 Pepco (b) 8 7 24 22 DPL (b) 4 3 13 11 ACE (b) 4 3 11 11 PHISCO (a)(b) 12 12 33 29 Successor Predecessor Successor Predecessor Pension and Other Postretirement Benefit Costs Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 March 24, 2016 to September 30, 2016 January 1, 2016 to March 23, 2016 Nine Months Ended September 30, 2015 PHI $ 28 $ 25 $ 58 $ 23 $ 73 _________ (a) These amounts primarily represent amounts billed to Exelon’s subsidiaries through intercompany allocations. These amounts are not included in the Generation, ComEd, PECO, BGE, PHI, Pepco, DPL or ACE amounts above.
Schedule Of Defined Contributions	The following table presents the matching contributions to the savings plans during the three and nine months ended September 30, 2016 and 2015 : Three Months Ended September 30, Nine Months Ended September 30, Savings Plan Matching Contributions 2016 2015 2016 2015 Exelon $ 51 $ 51 $ 107 $ 111 Generation 31 27 56 60 ComEd 10 10 23 23 PECO 3 3 7 7 BGE 2 5 5 10 BSC (a) 2 6 9 11 Pepco (b) — — 2 2 DPL (b) 1 1 2 2 ACE (b) — — 1 1 PHISCO (a)(b) 2 2 5 5 Successor Predecessor Successor Predecessor Savings Plan Matching Contributions Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 March 24, 2016 to September 30, 2016 January 1, 2016 to March 23, 2016 Nine Months Ended September 30, 2015 PHI $ 3 $ 3 $ 7 $ 3 $ 10 _________ (a) These amounts primarily represent amounts billed to Exelon and PHI's subsidiaries through intercompany allocations. These costs are not included in the Generation, ComEd, PECO, BGE, Pepco and DPL amounts above. (b) Pepco's, DPL's and PHISCO's matching contributions for the nine months ended September 30, 2016 include $1 million , $1 million ,and $1 million , respectively, of costs incurred prior to the closing of Exelon’s merger with PHI on March 23, 2016 , which is not included in Exelon’s matching contributions for the nine months ended September 30, 2016 .
Schedule of Net Benefit Costs [Table Text Block]	Pension Benefits Other Postretirement Benefits Components of net periodic benefit cost: 2016 2015 2016 2015 Service cost $ 92 $ 82 $ 27 $ 30 Interest cost 215 178 47 42 Expected return on assets (293 ) (257 ) (42 ) (38 ) Amortization of: Prior service cost (benefit) 3 3 (48 ) (43 ) Actuarial loss 142 142 18 20 Net periodic benefit cost $ 159 $ 148 $ 2 $ 11 Pension Benefits Other Postretirement Benefits 2016 (a) 2015 2016 (a) 2015 Components of net periodic benefit cost: Service cost $ 262 $ 245 $ 80 $ 89 Interest cost 616 533 138 125 Expected return on assets (847 ) (770 ) (121 ) (113 ) Amortization of: Prior service cost (benefit) 10 10 (138 ) (130 ) Actuarial loss 411 427 47 60 Net periodic benefit cost $ 452 $ 445 $ 6 $ 31 _______ (a) PHI net periodic benefit costs for the period prior to the merger are not included in the table above. Predecessor PHI Pension Benefits Other Postretirement Benefits Components of net periodic benefit cost: January 1, 2016 to March 23, 2016 Three Months Ended September 30, 2015 Nine Months Ended September 30, 2015 January 1, 2016 to March 23, 2016 Three Months Ended September 30, 2015 Nine Months Ended September 30, 2015 Service cost $ 12 $ 15 $ 43 $ 1 $ 2 $ 5 Interest cost 26 28 82 6 6 18 Expected return on assets (30 ) (35 ) (105 ) (5 ) (6 ) (17 ) Amortization of: Prior service cost (benefit) — — 1 (3 ) (3 ) (9 ) Actuarial loss 14 16 49 2 2 6 Net periodic benefit cost $ 22 $ 24 $ 70 $ 1 $ 1 $ 3

Severance (Tables)

Severance (Tables)	9 Months Ended
	Sep. 30, 2016
Restructuring and Related Activities [Abstract]
Activity of severance obligations for the corporate restructuring (excluding obligations recorded in equity)	Amounts included in the table below represent the severance liability recorded for the severance plans above for employees of each Registrant and exclude amounts included at Exelon and billed through intercompany allocations: Successor Severance Liability Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance at December 31, 2015 $ 35 $ 23 $ 3 $ — $ 1 $ — $ — $ — $ — Severance charges (a)(b) 136 63 1 — — 53 1 1 — Payments (39 ) (7 ) (1 ) — (1 ) (25 ) (1 ) (1 ) — Balance at September 30, 2016 $ 132 $ 79 $ 3 $ — $ — $ 28 $ — $ — $ — ______________ (a) Includes salary continuance and health and welfare severance benefits. Amounts primarily represent benefits provided for the PHI post-merger integration, the Clinton and Quad Cities early plant retirements and the cost management program. (b) Represents activity from March 24, 2016 to September 30, 2016 for PHI, Pepco, DPL and ACE. Exelon Generation ComEd PECO BGE Nine Months Ended September 30, 2016 Severance benefits (a) $ 18 $ 13 $ 3 $ 1 $ 1 _______ (a) The amounts above for Generation, ComEd, PECO and BGE include $7 million , $3 million , $1 million and $1 million , respectively, for amounts billed by BSC through intercompany allocations for the nine months ended September 30, 2016 .
Restructuring and Related Costs	Three Months Ended September 30, Nine Months Ended September 30, Acquisition, Integration and Financing Costs (a) 2016 2015 2016 2015 Exelon (b) $ 20 $ 22 $ 123 $ 84 Generation 9 10 29 30 ComEd (c) — 3 (6 ) 9 PECO 1 1 3 4 BGE (c) 1 2 (3 ) 4 Pepco (c) 3 1 26 3 DPL (c) 2 — 18 2 ACE 2 — 17 1 Successor Predecessor Successor Predecessor Three Months Ended September 30, Three Months Ended September 30, March 24 to September 30, January 1 to March 23, Nine Months Ended September 30, Acquisition, Integration and Financing Costs (a) 2016 2015 2016 2016 2015 PHI (c) $ 7 $ 3 $ 63 $ 29 $ 16 ______________ (a) The costs incurred are classified primarily within Operating and maintenance expense in the Registrants’ respective Consolidated Statements of Operations and Comprehensive Income, with the exception of the financing costs, which are included within Interest expense. Costs do not include merger commitments discussed above. (b) Reflects costs (benefits) recorded at Exelon related to financing, including mark-to-market activity on forward-starting interest rate swaps. Successor Exelon Generation ComEd PECO BGE PHI Pepco (b) DPL (c) ACE Nine Months Ended September 30, 2016 Severance benefits (a) $ 55 $ 9 $ 2 $ 1 $ 1 $ 42 $ 20 $ 12 $ 10 ______________ (a) The amounts above for Generation, ComEd, PECO, BGE, Pepco, DPL and ACE include amounts billed by BSC and/or PHISCO through intercompany allocations of $8 million , $2 million , $1 million , $1 million , $19 million , $11 million and $10 million for the nine months ended September 30, 2016 . For the three and nine months ended September 30, 2016 , the Registrants recorded the following severance costs (benefits) related to the early plant retirements within Operating and maintenance expense in their Consolidated Statements of Operations and Comprehensive Income, pursuant to the authoritative guidance for ongoing severance plans: Exelon Generation (a) Three Months Ended September 30, 2016 $ (2 ) $ (2 ) Nine Months Ended September 30, 2016 $ 44 $ 44 (a) The amounts above for Generation include $2 million for amounts billed by BSC through intercompany allocations for the nine months ended September 30, 2016 . Successor Exelon Generation (a) ComEd (a) PHI Three Months Ended September 30, 2016 $ 8 $ 7 $ — $ 1 September 30, 2015 (3 ) (3 ) — — Nine Months Ended September 30, 2016 $ 12 $ 10 $ 1 $ 1 September 30, 2015 18 17 1 —
Schedule of Restructuring Reserve by Type of Cost [Table Text Block]	Amounts included in the table below represent the severance liability recorded for the severance plans above for employees of each Registrant and exclude amounts included at Exelon and billed through intercompany allocations: Successor Severance Liability Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Balance at December 31, 2015 $ 35 $ 23 $ 3 $ — $ 1 $ — $ — $ — $ — Severance charges (a)(b) 136 63 1 — — 53 1 1 — Payments (39 ) (7 ) (1 ) — (1 ) (25 ) (1 ) (1 ) — Balance at September 30, 2016 $ 132 $ 79 $ 3 $ — $ — $ 28 $ — $ — $ — ______________ (a) Includes salary continuance and health and welfare severance benefits. Amounts primarily represent benefits provided for the PHI post-merger integration, the Clinton and Quad Cities early plant retirements and the cost management program. (b) Represents activity from March 24, 2016 to September 30, 2016 for PHI, Pepco, DPL and ACE. Exelon Generation ComEd PECO BGE Nine Months Ended September 30, 2016 Severance benefits (a) $ 18 $ 13 $ 3 $ 1 $ 1 _______ (a) The amounts above for Generation, ComEd, PECO and BGE include $7 million , $3 million , $1 million and $1 million , respectively, for amounts billed by BSC through intercompany allocations for the nine months ended September 30, 2016 .

Mezzanine Equity Mezzanine Eq40

Mezzanine Equity Mezzanine Equity (Tables)	9 Months Ended
	Sep. 30, 2016
Noncontrolling Interest [Abstract]
Redeemable Noncontrolling Interest [Table Text Block]	The following table summarizes the changes in the contingently redeemable noncontrolling interests for the nine months ended September 30, 2016 : Balance at December 31, 2015 $ 28 Cash received from noncontrolling interests 105 Release of contingency (107 ) Balance at September 30, 2016 $ 26

Changes in Accumulated Other 41

Changes in Accumulated Other Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2016
Changes in Accumulated Other Comprehensive Income [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	nine months ended September 30, 2016 and 2015 : Nine Months Ended September 30, 2016 Gains and (losses) on Cash Flow Hedges Unrealized Gains and (losses) on Marketable Securities Pension and Non-Pension Postretirement Benefit Plan Items Foreign Currency Items AOCI of Equity Investments Total Exelon (a) Beginning balance $ (19 ) $ 3 $ (2,565 ) $ (40 ) $ (3 ) $ (2,624 ) OCI before reclassifications (1 ) — (2 ) 3 (5 ) (5 ) Amounts reclassified from AOCI (b) (3 ) — 104 5 — 106 Net current-period OCI (4 ) — 102 8 (5 ) 101 Ending balance $ (23 ) $ 3 $ (2,463 ) $ (32 ) $ (8 ) $ (2,523 ) Generation (a) Beginning balance $ (21 ) $ 1 $ — $ (40 ) $ (3 ) $ (63 ) OCI before reclassifications — 1 — 3 1 5 Amounts reclassified from AOCI (b) (3 ) — — 5 — 2 Net current-period OCI (3 ) 1 — 8 1 7 Ending balance $ (24 ) $ 2 $ — $ (32 ) $ (2 ) $ (56 ) PECO (a) Beginning balance $ — $ 1 $ — $ — $ — $ 1 OCI before reclassifications — — — — — — Amounts reclassified from AOCI (b) — — — — — — Net current-period OCI — — — — — — Ending balance $ — $ 1 $ — $ — $ — $ 1 PHI Predecessor (a) Beginning balance January 1, 2016 $ (8 ) $ — $ (28 ) $ — $ — $ (36 ) OCI before reclassifications — — — — — — Amounts reclassified from AOCI (b) — — 1 — — 1 Net current-period OCI — — 1 — — 1 Ending balance March 23, 2016 (c) $ (8 ) $ — $ (27 ) $ — $ — $ (35 ) Nine Months Ended September 30, 2015 Gains and (losses) on Hedging Activity Unrealized Gains and (losses) on Marketable Securities Pension and Non-Pension Postretirement Benefit Plan Items Foreign Currency Items AOCI of Equity Investments Total Exelon (a) Beginning balance $ (28 ) $ 3 $ (2,640 ) $ (19 ) $ — $ (2,684 ) OCI before reclassifications (18 ) — (29 ) (17 ) — (64 ) Amounts reclassified from AOCI (b) 22 — 130 — — 152 Net current-period OCI 4 — 101 (17 ) — 88 Ending balance $ (24 ) $ 3 $ (2,539 ) $ (36 ) $ — $ (2,596 ) Generation (a) Beginning balance $ (18 ) $ 1 $ — $ (19 ) $ — $ (36 ) OCI before reclassifications (13 ) — — (17 ) — (30 ) Amounts reclassified from AOCI (b) 6 — — — — 6 Net current-period OCI (7 ) — — (17 ) — (24 ) Ending balance $ (25 ) $ 1 $ — $ (36 ) $ — $ (60 ) PECO (a) Beginning balance $ — $ 1 $ — $ — $ — $ 1 OCI before reclassifications — — — — — — Amounts reclassified from AOCI (b) — — — — — — Net current-period OCI — — — — — — Ending balance $ — $ 1 $ — $ — $ — $ 1 PHI Predecessor (a) Beginning balance $ (9 ) $ — $ (37 ) $ — $ — $ (46 ) OCI before reclassifications — — — — — — Amounts reclassified from AOCI (b) 1 — 4 — — 5 Net current-period OCI 1 — 4 — — 5 Ending balance $ (8 ) $ — $ (33 ) $ — $ — $ (41 ) ________ (a) All amounts are net of tax and noncontrolling interest. Amounts in parenthesis represent a decrease in AOCI. (b) See next tables for details about these reclassifications.
Reclassification out of Accumulated Other Comprehensive Income	The following tables present amounts reclassified out of AOCI to Net income for Exelon, Generation and PHI during the three and nine months ended September 30, 2016 and 2015 . Three Months Ended September 30, 2016 Details about AOCI components Items reclassified out of AOCI (a) Affected line item in the Statement of Operations and Comprehensive Income Exelon Generation Amortization of pension and other postretirement benefit plan items Prior service costs (b) $ 19 $ — Actuarial losses (b) (76 ) — Total before tax (57 ) — Tax benefit 22 — Net of tax $ (35 ) $ — Gains (losses) on foreign currency translation Other $ (5 ) $ (5 ) Other income and (deductions) Total before tax (5 ) (5 ) Tax expense — — Net of tax $ (5 ) $ (5 ) Total Reclassifications for the period $ (40 ) $ (5 ) Comprehensive income Nine Months Ended September 30, 2016 Details about AOCI components Items reclassified out of AOCI (a) Affected line item in the Statement of Operations and Comprehensive Income Predecessor January 1, 2016 to March 23, 2016 Exelon Generation PHI Gains and (losses) on cash flow hedges Other cash flow hedges $ 5 $ 5 $ — Interest expense Total before tax 5 5 — Tax expense (2 ) (2 ) — Net of tax $ 3 $ 3 $ — Comprehensive income Amortization of pension and other postretirement benefit plan items Prior service costs (b) $ 57 $ — $ — Actuarial losses (b) (227 ) — (1 ) Total before tax (170 ) — (1 ) Tax benefit 66 — — Net of tax $ (104 ) $ — $ (1 ) Gains (losses) on foreign currency translation Other $ (5 ) $ (5 ) $ — Other income and (deductions) Total before tax (5 ) (5 ) — Tax expense — — — Net of tax $ (5 ) $ (5 ) $ — Total Reclassifications $ (106 ) $ (2 ) $ (1 ) Comprehensive income Three Months Ended September 30, 2015 Details about AOCI components Items reclassified out of AOCI (a) Affected line item in the Statement of Operations and Comprehensive Income Predecessor Exelon Generation PHI Gains and (losses) on cash flow hedges Other cash flow hedges $ (4 ) $ (4 ) $ (1 ) Interest expense Total before tax (4 ) (4 ) (1 ) Tax expense 1 1 — Net of tax $ (3 ) $ (3 ) $ (1 ) Comprehensive income Amortization of pension and other postretirement benefit plan items Prior service costs (b) $ 19 $ — $ — Actuarial losses (b) (90 ) — (2 ) Total before tax (71 ) — (2 ) Tax expense 28 — 2 Net of tax $ (43 ) $ — $ — Total Reclassifications for the period $ (46 ) $ (3 ) $ (1 ) Comprehensive income Nine Months Ended September 30, 2015 Details about AOCI components Items reclassified out of AOCI (a) Affected line item in the Statement of Operations and Comprehensive Income Predecessor Exelon Generation PHI Gains and (losses) on cash flow hedges Terminated interest rate swaps $ (26 ) $ — $ — Other, net Energy related hedges 2 2 — Operating revenues Other cash flow hedges (11 ) (11 ) (1 ) Interest expense Total before tax (35 ) (9 ) (1 ) Tax benefit 13 3 — Net of tax $ (22 ) $ (6 ) $ (1 ) Comprehensive income Amortization of pension and other postretirement benefit plan items Prior service costs (b) $ 57 $ — $ — Actuarial losses (b) (270 ) — (7 ) Total before tax (213 ) — (7 ) Tax benefit 83 — 3 Net of tax $ (130 ) $ — $ (4 ) Total Reclassifications $ (152 ) $ (6 ) $ (5 ) Comprehensive income _______ (a) Amounts in parenthesis represent a decrease in net income. (b) This AOCI component is included in the computation of net periodic pension and OPEB cost (see Note 13 — Retirement Benefits for additional details).
Schedule Of Other Comprehensive Income Loss Tax	The following table presents income tax expense (benefit) allocated to each component of other comprehensive income (loss) during the three and nine months ended September 30, 2016 and 2015 : Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 Exelon Pension and non-pension postretirement benefit plans: Prior service benefit reclassified to periodic benefit cost $ 7 $ 8 $ 22 $ 22 Actuarial loss reclassified to periodic cost (29 ) (35 ) (88 ) (105 ) Pension and non-pension postretirement benefit plans valuation adjustment 1 — 1 17 Change in unrealized gain/(loss) on cash flow hedges (1 ) 3 3 (3 ) Change in unrealized loss on equity investments — — 3 — Change in unrealized gain on marketable securities (1 ) — (1 ) — Total $ (23 ) $ (24 ) $ (60 ) $ (69 ) Generation Change in unrealized gain/(loss) on cash flow hedges $ (2 ) $ 3 $ 1 $ 4 Change in unrealized loss on equity investments — — 3 — Change in unrealized gain on marketable securities — — — — Total $ (2 ) $ 3 $ 4 $ 4

Earnings Per Share and Equity42

Earnings Per Share and Equity (Tables)	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Reconciliation of basic and diluted earnings per share	Three Months Ended September 30, Nine Months Ended September 30, Exelon 2016 2015 2016 2015 Net income attributable to common shareholders $ 490 $ 629 $ 930 $ 1,959 Weighted average common shares outstanding — basic 925 913 924 879 Assumed exercise and/or distributions of stock-based awards 2 2 2 4 Weighted average common shares outstanding — diluted 927 915 926 883

Commitments and Contingencies43

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2016
Commitments And Contingencies Tables Disclosure [Line Items]
Energy Commitments	s
Utility Energy Purchase Commitments	s
Fuel Purchase Commitments	s
Other Purchase Obligation	s
Commercial Commitments	The Registrants’ commercial commitments as of September 30, 2016 , representing commitments potentially triggered by future events were as follows: Successor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Letters of credit (non-debt) (a) $ 1,720 $ 1,650 $ 16 $ 23 $ 2 $ 1 $ — $ — $ 1 Surety bonds (b) 1,084 984 10 9 11 16 9 4 3 Financing trust guarantees 628 — 200 178 250 — — — — Nuclear insurance premiums (c) 3,045 3,045 — — — — — — — Guaranteed lease residual values (d) 20 — — — — 20 6 7 5 Total commercial commitments $ 6,497 $ 5,679 $ 226 $ 210 $ 263 $ 37 $ 15 $ 11 $ 9 ________ (a) Letters of credit (non-debt) - Exelon and certain subsidiaries maintain non-debt letters of credit to provide credit support for certain transactions as requested by third parties. (b) Surety bonds—Guarantees issued related to contract and commercial agreements, excluding bid bonds. (c)
Accrued environmental liabilities	of September 30, 2016 and December 31, 2015 , the Registrants had accrued the following undiscounted amounts for environmental liabilities in Other current liabilities and Other deferred credits and other liabilities within their respective Consolidated Balance Sheets: September 30, 2016 Total Environmental Investigation and Remediation Reserve Portion of Total Related to MGP Investigation and Remediation (a) Exelon $ 427 $ 318 Generation 76 — ComEd 283 281 PECO 36 34 BGE 2 2 PHI (Successor) 30 1 Pepco 27 — DPL 2 1 ACE 1 — December 31, 2015 Total Environmental Investigation and Remediation Reserve Portion of Total Related to MGP Investigation and Remediation (a) Exelon $ 369 $ 301 Generation 63 — ComEd 266 264 PECO 37 35 BGE 3 2 PHI (Predecessor) 33 1 Pepco 24 — DPL 3 1 ACE 1 — _____________________________ (a) For BGE, includes reserve for Riverside, a gas purification site. See discussion below for additional information.
Exelon Generation Co L L C [Member] | Equity Method Investments [Member]
Commitments And Contingencies Tables Disclosure [Line Items]
Other Commitments	, Generation’s estimated commitments relating to its equity purchase agreements, including the in-kind services contributions, is anticipated to be as follows: Total 2016 (a) $ 79 2017 25 2018 4 Total $ 108

Supplemental Financial Inform44

Supplemental Financial Information (Tables)	9 Months Ended
	Sep. 30, 2016
Supplemental Financial Information [Abstract]
Components of non-operating income and expenses	The following tables provide additional information about the Registrants’ Consolidated Statements of Operations and Comprehensive Income for the three and nine months ended September 30, 2016 and 2015 : Three Months Ended September 30, 2016 Successor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Other, Net Decommissioning-related activities: Net realized income on decommissioning trust funds (a) Regulatory agreement units $ 57 $ 57 $ — $ — $ — $ — $ — $ — $ — Non-regulatory agreement units 35 35 — — — — — — — Net unrealized gains on decommissioning trust funds Regulatory agreement units 155 155 — — — — — — — Non-regulatory agreement units 116 116 — — — — — — — Net unrealized losses on pledged assets Zion Station decommissioning (5 ) (5 ) — — — — — — — Regulatory offset to decommissioning trust fund-related activities (b) (168 ) (168 ) — — — — — — — Total decommissioning-related activities 190 190 — — — — — — — Investment income 2 1 — (1 ) — — — — — Interest income related to uncertain income tax positions 8 — — — — — — — — Penalty related to uncertain income tax positions (c) (106 ) — (86 ) — — — — — — AFUDC — Equity 19 — 5 2 5 7 5 1 1 Other 7 (6 ) 1 1 — 12 7 2 1 Other, net $ 120 $ 185 $ (80 ) $ 2 $ 5 $ 19 $ 12 $ 3 $ 2 Successor Predecessor Nine Months Ended September 30, 2016 March 24, 2016 to September 30, 2016 January 1, 2016 to March 23, 2016 Exelon Generation ComEd PECO BGE Pepco DPL ACE PHI PHI Other, Net Decommissioning-related activities: Net realized income on decommissioning trust funds (a) Regulatory agreement units $ 181 $ 181 $ — $ — $ — $ — $ — $ — $ — $ — Non-regulatory agreement units 95 95 — — — — — — — — Net unrealized gains on decommissioning trust funds Regulatory agreement units 286 286 — — — — — — — — Non-regulatory agreement units 216 216 — — — — — — — — Net unrealized losses on pledged assets Zion Station decommissioning (2 ) (2 ) — — — — — — — — Regulatory offset to decommissioning trust fund-related activities (b) (380 ) (380 ) — — — — — — — — Total decommissioning-related activities 396 396 — — — — — — — — Investment income (expense) 14 6 — (1 ) 2 (d) — — — 1 — Long-term lease income 4 — — — — — — — — — Interest income related to uncertain income tax positions 13 — — — — 1 — 1 — — Penalty income related to uncertain income tax positions (c) (106 ) — (86 ) — — — — — — — AFUDC — Equity 43 — 8 6 14 14 3 5 15 7 Loss on debt extinguishment (3 ) (2 ) — — — — — — — — Other 16 (5 ) 6 1 — 13 6 2 15 (11 ) Other, net $ 377 $ 395 $ (72 ) $ 6 $ 16 $ 28 $ 9 $ 8 $ 31 $ (4 ) Three Months Ended September 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Other, Net Decommissioning-related activities: Net realized income on decommissioning trust funds (a) Regulatory agreement units $ 39 $ 39 $ — $ — $ — $ — $ — $ — $ — Non-regulatory agreement units 18 18 — — — — — — — Net unrealized losses on decommissioning trust funds Regulatory agreement units (301 ) (301 ) — — — — — — — Non-regulatory agreement units (218 ) (218 ) — — — — — — — Regulatory offset to decommissioning trust fund-related activities (b) 207 207 — — — — — — — Total decommissioning-related activities (255 ) (255 ) — — — — — — — Investment income (expense) 4 1 — (1 ) 1 (d) — — — — Long-term lease income 4 — — — — — — — — AFUDC — Equity 6 — 1 1 4 2 3 — — Other (3 ) (3 ) 3 1 (1 ) 25 5 4 1 Other, net $ (244 ) $ (257 ) $ 4 $ 1 $ 4 $ 27 $ 8 $ 4 $ 1 Nine Months Ended September 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Other, Net Decommissioning-related activities: Net realized income on decommissioning trust funds (a) Regulatory agreement units $ 203 $ 203 $ — $ — $ — $ — $ — $ — $ — Non-regulatory agreement units 122 122 — — — — — — — Net unrealized losses on decommissioning trust funds Regulatory agreement units (385 ) (385 ) — — — — — — — Non-regulatory agreement units (274 ) (274 ) — — — — — — — Net unrealized gains on pledged assets Zion Station decommissioning 9 9 — — — — — — Regulatory offset to decommissioning trust fund-related activities (b) 129 129 — — — — — — — Total decommissioning-related activities (196 ) (196 ) — — — — — — — Investment income (expense) 6 1 — (1 ) 3 (d) — — — — Long-term lease income 12 — — — — — — — — Interest income related to uncertain income tax positions — 1 — — — — — — 1 AFUDC — Equity 16 — 2 4 10 11 9 1 1 Terminated interest rate swaps (e) (26 ) — — — — — — — — Other 9 1 12 — — 37 12 7 2 Other, net $ (179 ) $ (193 ) $ 14 $ 3 $ 13 $ 48 $ 21 $ 8 $ 4 ____ (a) Includes investment income and realized gains and losses on sales of investments of the trust funds. (b) Includes the elimination of NDT fund activity for the Regulatory Agreement Units, including the elimination of net income taxes related to all NDT fund activity for those units. See Note 16 — Asset Retirement Obligations of the Exelon 2015 Form 10-K for additional information regarding the accounting for nuclear decommissioning. (c) See Note 11 — Income Taxes for discussion of the penalty related to the Tax Court's decision on Exelon's like-kind exchange tax position. (d) Relates to the cash return on BGE’s rate stabilization deferral. See Note 3 — Regulatory Matters of the Exelon 2015 Form 10-K for additional information regarding the rate stabilization deferral. (e) In January 2015, in connection with Generation's $750 million issuance of five-year Senior Unsecured Notes, Exelon terminated certain floating-to-fixed interest rate swaps. As the original forecasted transactions were a series of future interest payments over a ten year period, a portion of the anticipated interest payments were probable not to occur. As a result, $26 million of anticipated payments were reclassified from AOCI to Other, net in Exelon's Consolidated Statement of Operations and Comprehensive Income.
Components of depreciation, amortization and accretion, and other, net	The following tables provide additional information regarding the Registrants’ Consolidated Statements of Cash Flows for the nine months ended September 30, 2016 and 2015 : Successor Predecessor Nine Months Ended September 30, 2016 March 24, 2016 to September 30, 2016 January 1, 2016 to March 23, 2016 Exelon Generation ComEd PECO BGE Pepco DPL ACE PHI PHI Depreciation, amortization, accretion and depletion Property, plant and equipment (a) $ 2,490 $ 1,297 $ 524 $ 181 $ 223 $ 128 $ 82 $ 61 $ 215 $ 94 Amortization of regulatory assets (a) 293 — 49 20 84 93 38 69 140 58 Amortization of intangible assets, net (a) 38 32 — — — — — — — — Amortization of energy contract assets and liabilities (b) (7 ) (7 ) — — — — — — — — Nuclear fuel (c) 862 862 — — — — — — — — ARO accretion (d) 333 332 1 — — — — — — — Total depreciation, amortization, accretion and depletion $ 4,009 $ 2,516 $ 574 $ 201 $ 307 $ 221 $ 120 $ 130 $ 355 $ 152 Nine Months Ended September 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Depreciation, amortization, accretion and depletion Property, plant and equipment (a) $ 1,648 $ 739 $ 471 $ 179 $ 216 $ 292 $ 122 $ 76 $ 57 Amortization of regulatory assets (a) 131 — 57 19 55 182 69 37 78 Amortization of intangible assets, net (a) 39 35 — — — — — — — Amortization of energy contract assets and liabilities (b) (20 ) (19 ) — — — — — — — Nuclear fuel (c) 841 841 — — — — — — — ARO accretion (d) 291 291 — — — — — — — Total depreciation, amortization, accretion and depletion $ 2,930 $ 1,887 $ 528 $ 198 $ 271 $ 474 $ 191 $ 113 $ 135 ________ (a) Included in Depreciation and amortization on the Registrants' Consolidated Statements of Operations and Comprehensive Income. (b) Included in Operating revenues or Purchased power and fuel expense on the Registrants’ Consolidated Statements of Operations and Comprehensive Income. (c) Included in Purchased power and fuel expense on the Registrants’ Consolidated Statements of Operations and Comprehensive Income. (d) Included in Operating and maintenance expense on the Registrants’ Consolidated Statements of Operations and Comprehensive Income.
Cash Flow Supplemental Disclosures	Successor Predecessor Nine Months Ended September 30, 2016 March 24, 2016 to September 30, 2016 January 1, 2016 to March 23, 2016 Exelon Generation ComEd PECO BGE Pepco DPL ACE PHI PHI Other non-cash operating activities: Pension and non-pension postretirement benefit costs $ 458 $ 163 $ 124 $ 25 $ 50 $ 24 $ 13 $ 11 $ 58 $ 23 Loss from equity method investments 15 16 — — — — — — — — Provision for uncollectible accounts 107 14 31 24 12 15 12 18 27 16 Stock-based compensation costs 88 — — — — — — — — 3 Other decommissioning-related activity (a) (237 ) (237 ) — — — — — — — — Energy-related options (b) (20 ) (20 ) — — — — — — — — Amortization of regulatory asset related to debt costs 7 — 3 1 — 2 — 1 2 1 Amortization of rate stabilization deferral 62 — — — 62 3 3 — — 5 Amortization of debt fair value adjustment (9 ) (9 ) — — — — — — — — Discrete impacts from EIMA (c) (36 ) — (36 ) — — — — — — — Amortization of debt costs 26 12 (3 ) 2 3 — — — — — Provision for excess and obsolete inventory 74 70 4 — — 1 1 1 — 1 Merger-related commitments (d)(e) 508 3 — — — 125 73 110 308 — Severance costs 130 57 — — — — — — 53 — Asset retirement costs — — — — — — 5 2 — — Lower of cost or market inventory adjustment 36 36 — — — — — — — — Other 15 24 (1 ) (3 ) (18 ) (2 ) (8 ) (5 ) (7 ) (3 ) Total other non-cash operating activities $ 1,224 $ 129 $ 122 $ 49 $ 109 $ 168 $ 99 $ 138 $ 441 $ 46 Non-cash investing and financing activities: Change in capital expenditures not paid $ (338 ) $ (289 ) $ (42 ) $ (4 ) $ 17 $ 15 $ (10 ) $ 2 $ (5 ) $ 11 Fair value of net assets contributed to Generation in connection with the PHI merger, net of cash (d)(f) — 119 — — — — — — — — Fair value of net assets distributed to Exelon in connection with the PHI Merger, net of cash (d)(f) — — — — — — — — 129 — Fair value of pension obligation transferred in connection with the PHI Merger — — — — — — — — 53 — Assumption of member purchase liability — — — — — — — — 29 — Assumption of merger commitment liability — — — — — 33 — — 33 — Change in PPE related to ARO update 476 476 — — — — — — — — Indemnification of like-kind exchange position (g) — — 157 — — — — — — — Non-cash financing of capital projects 84 84 — — — — — — — — Nine Months Ended September 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Other non-cash operating activities: Pension and non-pension postretirement benefit costs $ 476 $ 200 $ 155 $ 29 $ 49 $ 73 $ 22 $ 11 $ 11 Loss from equity method investments 3 4 — — — — — — — Provision for uncollectible accounts 114 15 46 37 15 49 15 18 15 Stock-based compensation costs 102 — — — — 9 — — — Other decommissioning-related activity (a) (31 ) (31 ) — — — — — — — Energy-related options (b) 18 18 — — — — — — — Amortization of regulatory asset related to debt costs — — — — — 4 2 — — Amortization of rate stabilization deferral 60 — — — 60 3 3 1 — Amortization of debt fair value adjustment (34 ) (9 ) — — — — — — — Discrete impacts from EIMA (c) 101 — 101 — — — — — — Amortization of debt costs 43 12 3 2 2 1 — — — Provision for excess and obsolete inventory 7 8 — — — 1 — — — Lower of cost or market inventory adjustment 15 15 — — — — — — — Other (18 ) (5 ) 7 1 (15 ) 3 — 1 1 Total other non-cash operating activities $ 856 $ 227 $ 312 $ 69 $ 111 $ 143 $ 42 $ 31 $ 27 Non-cash investing and financing activities: Change in capital expenditures not paid $ 59 $ 48 $ 62 $ (23 ) $ (14 ) $ (3 ) $ (1 ) $ 2 $ — Nuclear fuel procurement (d) — — — — — — — — — Change in PPE related to ARO update 811 811 — — — — — — — Indemnification of like-kind exchange position (g) — — 5 — — — — — — Non-cash financing of capital projects 52 52 — — — — — — — Long-term software licensing agreement (f) 95 — — — — — — — — ________ (a) Includes the elimination of NDT fund activity for the Regulatory Agreement Units, including the elimination of operating revenues, ARO accretion, ARC amortization, investment income and income taxes related to all NDT fund activity for these units. See Note 16 - Asset Retirement Obligations of the Exelon 2015 Form 10-K for additional information regarding the accounting for nuclear decommissioning. (b) Includes option premiums reclassified to realized at the settlement of the underlying contracts and recorded in Operating revenues. (c) Reflects the change in distribution rates pursuant to EIMA, which allows for the recovery of costs by a utility through a pre-established performance-based formula rate tariff. See Note 5 — Regulatory Matters for more information. (d) See Note 4 — Mergers, Acquisitions and Dispositions for additional information related to the merger with PHI. (e) Excludes $5 million of forgiveness of Accounts receivable related to merger commitments recorded in connection with the PHI Merger, the balance is included within Provision for uncollectible accounts. (f) Immediately following closing of the PHI Merger, the net assets associated with PHI's unregulated business interests were distributed by PHI to Exelon. Exelon contributed a portion of such net assets to Generation. (g) See Note 11 — Income Taxes for discussion of the like-kind exchange tax position.
Supplemental Balance Sheet Disclosures	The following tables provide additional information about assets and liabilities of the Registrants as of September 30, 2016 and December 31, 2015 : Successor September 30, 2016 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Property, plant and equipment: Accumulated depreciation and amortization $ 18,354 (a) $ 10,004 (a) $ 3,841 $ 3,213 $ 3,198 $ 146 $ 3,026 $ 1,171 $ 1,008 Accounts receivable: Allowance for uncollectible accounts $ 330 $ 85 $ 82 $ 78 $ 39 $ 46 $ 15 $ 14 $ 17 Predecessor December 31, 2015 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Property, plant and equipment: Accumulated depreciation and amortization $ 16,375 (b) $ 8,639 (b) $ 3,710 $ 3,101 $ 3,016 $ 5,341 $ 2,929 $ 1,139 $ 968 Accounts receivable: Allowance for uncollectible accounts $ 284 $ 77 $ 75 $ 83 $ 49 $ 56 $ 17 $ 17 $ 17 _______ (a) Includes accumulated amortization of nuclear fuel in the reactor core of $3,198 million . (b) Includes accumulated amortization of nuclear fuel in the reactor core of $2,861 million
Schedule Of Taxes Excluding Income And Excise Taxes [Text Block]	The following utility taxes are included in revenues and expenses for the three and nine months ended September 30, 2016 and 2015 . Generation’s utility tax expense represents gross receipts tax related to its retail operations and the utility registrants' utility tax expense represents municipal and state utility taxes and gross receipts taxes related to their operating revenues. The offsetting collection of utility taxes from customers is recorded in revenues on the Registrants’ Consolidated Statements of Operations and Comprehensive Income. Three Months Ended September 30, 2016 Successor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Utility taxes $ 255 $ 35 $ 67 $ 40 $ 21 $ 92 $ 87 $ 5 $ — Successor Predecessor Nine Months Ended September 30, 2016 March 24, 2016 to September 30, 2016 January 1, 2016 to March 23, 2016 Exelon Generation ComEd PECO BGE Pepco DPL ACE PHI PHI Utility taxes $ 624 $ 90 $ 186 $ 106 $ 66 $ 240 $ 14 $ — $ 176 $ 78 Three Months Ended September 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Utility taxes $ 151 $ 28 $ 63 $ 37 $ 23 $ 86 $ 82 $ 4 $ — Nine Months Ended September 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Utility taxes $ 430 $ 79 $ 180 $ 104 $ 67 $ 253 $ 239 $ 14 $ —

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2016
Segment Reporting Information [Line Items]
Analysis and reconciliation of reportable segment information	An analysis and reconciliation of the Registrants’ reportable segment information to the respective information in the consolidated financial statements for the three and nine months ended September 30, 2016 and 2015 is as follows: Three Months Ended September 30, 2016 and 2015 Successor Generation (a) ComEd PECO BGE PHI (b) Other (c) Intersegment Exelon Operating revenues (d) : 2016 Competitive businesses electric revenues $ 4,322 $ — $ — $ — $ — $ — $ (499 ) $ 3,823 Competitive businesses natural gas revenues 326 — — — — — — 326 Competitive businesses other revenues 387 — — — — — (1 ) 386 Rate-regulated electric revenues — 1,497 740 735 1,366 — (8 ) 4,330 Rate-regulated natural gas revenues — — 48 77 17 — (5 ) 137 Shared service and other revenues — — — — 11 362 (373 ) — 2015 Competitive businesses electric revenues $ 4,299 $ — $ — $ — $ — $ — $ (204 ) $ 4,095 Competitive businesses natural gas revenues 347 — — — — — — 347 Competitive businesses other revenues 122 — — — — — — 122 Rate-regulated electric revenues — 1,376 691 655 — — (1 ) 2,721 Rate-regulated natural gas revenues — — 49 70 — — (3 ) 116 Shared service and other revenues — — — — — 348 (348 ) — Intersegment revenues (e) : 2016 $ 500 $ 4 $ 2 $ 7 $ 11 $ 362 $ (885 ) $ 1 2015 205 1 1 3 — 347 (555 ) 2 Net income (loss): 2016 $ 271 $ 37 $ 122 $ 56 $ 166 $ (125 ) $ (1 ) $ 526 2015 332 149 90 54 — (36 ) (2 ) 587 Total assets: September 30, 2016 $ 47,568 $ 28,020 $ 11,041 $ 8,857 $ 21,063 $ 9,883 $ (11,897 ) $ 114,535 December 31, 2015 46,529 26,532 10,367 8,295 — 15,389 (11,728 ) 95,384
Analysis and reconciliation of reportable segment revenues for Generation	_________ (a) Generation includes the six power marketing reportable segments shown below: Mid-Atlantic, Midwest, New England, New York, ERCOT and Other Power Regions. Intersegment revenues for Generation for the nine months ended September 30, 2016 include revenue from sales to PECO of $234 million and sales to BGE of $489 million in the Mid-Atlantic region, and sales to ComEd of $38 million in the Midwest region. For the nine months ended September 30, 2015 , intersegment revenues for Generation include revenue from sales to PECO of $173 million and sales to BGE of $376 million in the Mid-Atlantic region, and sales to ComEd of $17 million in the Midwest region. For the Successor period of March 24, 2016 to September 30, 2016 , intersegment revenues for Generation include revenue from sales to Pepco of $223 million , sales to DPL of $109 million , and sales to ACE of $28 million in the Mid-Atlantic region. (b) Amounts included represent activity for PHI's successor period, March 24, 2016 through September 30, 2016 . PHI includes the three reportable segments: Pepco, DPL and ACE. See tables below for PHI's predecessor periods, including Pepco, DPL and ACE, for January 1, 2016 to March 23, 2016 and for the nine months ended September 30, 2015 . (c) Other primarily includes Exelon’s corporate operations, shared service entities and other financing and investment activities. (d) Includes gross utility tax receipts from customers. The offsetting remittance of utility taxes to the governing bodies is recorded in expenses on the Registrants’ Consolidated Statements of Operations and Comprehensive Income. See Note 19 — Supplemental Financial Information for total utility taxes for the nine months ended September 30, 2016 and 2015 . (e) Intersegment revenues exclude sales to unconsolidated affiliates. The intersegment profit associated with Generation’s sale of certain products and services by and between Exelon’s segments is not eliminated in consolidation due to the recognition of intersegment profit in accordance with regulatory accounting guidance. For Exelon, these amounts are included in Operating revenues in the Consolidated Statements of Operations and Comprehensive Income. Generation total revenues: Nine Months Ended September 30, 2016 Nine Months Ended September 30, 2015 Revenues (a) Intersegment Total Revenues (a)(c) Intersegment (c) Total (c) Mid-Atlantic $ 4,776 $ (40 ) $ 4,736 $ 4,560 $ (69 ) $ 4,491 Midwest 3,330 13 3,343 3,634 (1 ) 3,633 New England 1,278 (6 ) 1,272 1,752 (6 ) 1,746 New York 906 (33 ) 873 783 (5 ) 778 ERCOT 659 6 665 691 (4 ) 687 Other Power Regions 728 (42 ) 686 940 (60 ) 880 Total Revenues for Reportable Segments 11,677 (102 ) 11,575 12,360 (145 ) 12,215 Other (b) 1,686 102 1,788 2,481 145 2,626 Total Generation Consolidated Operating Revenues $ 13,363 $ — $ 13,363 $ 14,841 $ — $ 14,841 __________ (a) Includes all wholesale and retail electric sales to third parties and affiliated sales to the Utility Registrants. (b) Other represents activities not allocated to a region. See text above for a description of included activities. Includes a $10 million decrease to revenues and a $19 million increase to revenues for the amortization of intangible assets and liabilities related to commodity contracts recorded at fair value for the nine months ended September 30, 2016 and 2015 , respectively, unrealized mark-to-market losses of $366 million and gains of $171 million for the nine months ended September 30, 2016 and 2015 , respectively, and elimination of intersegment revenues. (c) Exelon corrected an error in the September 30, 2015 balances within Intersegment Revenue and Revenue from external customers for an overstatement of $144 million of Intersegment Revenue for Reportable Segments for the nine months ended September 30, 2015 , an understatement of Revenue from external customers for Reportable Segments of $144 million for the nine months ended September 30, 2015 , an understatement of $144 million of Intersegment Revenue for Other for the nine months ended September 30, 2015 , and an overstatement of Revenue from external customers for Other of $144 million for the nine months ended September 30, 2015 . This error is not considered material to any prior period, and there is no impact to Total Revenues. Generation total revenues net of purchased power and fuel expense: Nine Months Ended September 30, 2016 Nine Months Ended September 30, 2015 RNF from external customers (a) Intersegment RNF Total RNF RNF from external customers (a)(c) Intersegment RNF (c) Total RNF (c) Mid-Atlantic $ 2,541 $ 15 $ 2,556 $ 2,679 $ (2 ) $ 2,677 Midwest 2,225 4 2,229 2,220 (15 ) 2,205 New England 373 (23 ) 350 425 (46 ) 379 New York 607 (15 ) 592 462 40 502 ERCOT 335 (104 ) 231 344 (109 ) 235 Other Power Regions 357 (104 ) 253 341 (148 ) 193 Total Revenues net of purchased power and fuel expense for Reportable Segments 6,438 (227 ) 6,211 6,471 (280 ) 6,191 Other (b) 316 227 543 570 280 850 Total Generation Revenues net of purchased power and fuel expense $ 6,754 $ — $ 6,754 $ 7,041 $ — $ 7,041
Exelon Generation Co L L C [Member]
Segment Reporting Information [Line Items]
Analysis and reconciliation of reportable segment revenues for Generation	Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 RNF (a) Intersegment RNF Total RNF RNF (a)(c) Intersegment RNF (c) Total RNF (c) Mid-Atlantic $ 881 $ 6 $ 887 $ 979 $ 18 $ 997 Midwest 782 (1 ) 781 760 (4 ) 756 New England 170 (10 ) 160 148 (15 ) 133 New York 195 (1 ) 194 157 13 170 ERCOT 144 (51 ) 93 166 (55 ) 111 Other Power Regions 143 (66 ) 77 154 (71 ) 83 Total Revenues net of purchased power and fuel for Reportable Segments 2,315 (123 ) 2,192 2,364 (114 ) 2,250 Other (b) 131 123 254 (115 ) 114 (1 ) Total Generation Revenues net of purchased power and fuel expense $ 2,446 $ — $ 2,446 $ 2,249 $ — $ 2,249 __________ (a) Includes purchases and sales from/to third parties and affiliated sales to the Utility Registrants. (b) Other represents activities not allocated to a region. See text above for a description of included activities. Includes a $22 million decrease and a $4 million decrease to RNF for the amortization of intangible assets and liabilities related to commodity contracts for the three months ended September 30, 2016 and 2015 , respectively, unrealized mark-to-market gains of $88 million and losses of $139 million for the three months ended September 30, 2016 and 2015 , respectively, accelerated nuclear fuel amortization associated with nuclear decommissioning as discussed in Note 7 — Early Nuclear Plant Retirements of the Combined Notes to Consolidated Financial Statements of $28 million for the three months ended September 30, 2016 , and the elimination of intersegment revenue net of purchased power and fuel expense. (c) Exelon corrected an error in the September 30, 2015 balances within Intersegment RNF and RNF from external customers for an understatement of $12 million of Intersegment RNF for Reportable Segments for the three months ended September 30, 2015 , and an overstatement of $12 million of Intersegment RNF for Other for the three months ended September 30, 2015 . This also included an understatement of total RNF for Reportable Segments and an overstatement of total RNF for Other of $13 million for the three months ended September 30, 2015 . The error is not considered material to any prior period, and there is no net impact to Generation Total RNF for 2015. Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 Revenues (a) Intersegment Total Revenues (a)(c) Intersegment (c) Total (c) Mid-Atlantic $ 1,813 $ (13 ) $ 1,800 $ 1,640 $ (8 ) $ 1,632 Midwest 1,163 1 1,164 1,152 (1 ) 1,151 New England 455 (4 ) 451 520 — 520 New York 331 (8 ) 323 254 (4 ) 250 ERCOT 289 6 295 317 (1 ) 316 Other Power Regions 271 (33 ) 238 416 (40 ) 376 Total Revenues for Reportable Segments 4,322 (51 ) 4,271 4,299 (54 ) 4,245 Other (b) 713 51 764 469 54 523 Total Generation Consolidated Operating Revenues $ 5,035 $ — $ 5,035 $ 4,768 $ — $ 4,768 __________ (a) Includes all wholesale and retail electric sales to third parties and affiliated sales to the Utility Registrants. (b) Other represents activities not allocated to a region. See text above for a description of included activities. Includes a $21 million decrease and $3 million decrease to revenues for the amortization of intangible assets and liabilities related to commodity contracts recorded at fair value for the three months ended September 30, 2016 and 2015 , respectively, unrealized mark-to-market gains of $187 million and losses of $7 million for the three months ended September 30, 2016 and 2015 , respectively, and elimination of intersegment revenues. (c) Exelon corrected an error in the September 30, 2015 balances within Intersegment Revenue and Revenue from external customers for an overstatement of $54 million of Intersegment Revenue for Reportable Segments for the three months ended September 30, 2015 , an understatement of Revenue from external customers for Reportable Segments of $54 million for the three months ended September 30, 2015 , an understatement of $54 million of Intersegment Revenue for Other for the three months ended September 30, 2015 , and an overstatement of Revenue from external customers for Other of $54 million for the three months ended September 30, 2015 . This error is not considered material to any prior period, and there is no impact to Total Revenues.

Significant Accounting Polici46

Significant Accounting Policies - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended	9 Months Ended
	Mar. 23, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015	Jan. 01, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net Cash Provided by (Used in) Financing Activities				$ 1,251,000,000	$ 5,402,000,000
Net Cash Provided by (Used in) Operating Activities				7,363,000,000	5,674,000,000
Pepco Holdings LLC [Member] | Predecessor [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results		$ 1,000,000			1,000,000
Net Cash Provided by (Used in) Financing Activities	$ 372,000,000				491,000,000
Net Cash Provided by (Used in) Operating Activities	$ 264,000,000				601,000,000
Pepco Holdings LLC [Member] | Successor [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net Cash Provided by (Used in) Financing Activities			$ 65,000,000
Net Cash Provided by (Used in) Operating Activities			$ 546,000,000
Delmarva Power and Light Company [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results		1,000,000
Net Cash Provided by (Used in) Financing Activities				(14,000,000)	53,000,000
Net Cash Provided by (Used in) Operating Activities				267,000,000	188,000,000
Atlantic City Electric Company [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results					1,000,000
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets						$ 12,000,000
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income		8,000,000			9,000,000
Net Cash Provided by (Used in) Financing Activities				74,000,000	40,000,000
Net Cash Provided by (Used in) Operating Activities				315,000,000	178,000,000
Potomac Electric Power Company [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Interest		$ 1,000,000
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results					1,000,000
Net Cash Provided by (Used in) Financing Activities				28,000,000	148,000,000
Net Cash Provided by (Used in) Operating Activities				$ 504,000,000	$ 213,000,000

Variable Interest Entities - Na

Variable Interest Entities - Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2016USD ($)VIE	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)VIE	Sep. 30, 2015USD ($)	Aug. 31, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2015USD ($)VIE	Jul. 31, 2014USD ($)	Apr. 01, 2014USD ($)
Variable Interest Entity [Line Items]
Other Commitment	$ 6,497,000,000		$ 6,497,000,000		$ 513,000,000	$ 508,000,000
Variable Interest Entity, Financial or Other Support, Amount			$ 16,000,000
Number of Variable Interest Entities not consolidated by equity holders | VIE	9		9				8
Number Of Variable Interest Entities Consolidated | VIE	9		9				7
Guarantor Obligations, Current Carrying Value	$ 75,000,000		$ 75,000,000
Guarantor Obligations, Maximum Exposure, Undiscounted	50,000,000		50,000,000
Payments for Restructuring			39,000,000
Note Receivable				$ 27,000,000
Equity Method Investment Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Summarized Financial Information, Equity Excluding Noncontrolling Interests	250,000,000		250,000,000				$ 172,000,000
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Guarantor Obligations, Current Carrying Value	275,000,000		275,000,000
Exelon Generation Co L L C [Member]
Variable Interest Entity [Line Items]
Other Commitment	$ 5,679,000,000		$ 5,679,000,000					$ 91,000,000
Equity Method Investment, Ownership Percentage	50.01%		50.01%
Related Party Purchase Of Nuclear Output By Third Party Percentage			49.99%
Payments for Restructuring			$ 7,000,000
Exelon Generation Co L L C [Member] | Equity Method Investment Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Guarantor Obligations, Current Carrying Value	$ 275,000,000		275,000,000
Equity Method Investment, Summarized Financial Information, Equity Excluding Noncontrolling Interests							$ 78,000,000
Exelon Generation Co L L C [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Guarantor Obligations, Current Carrying Value	8,000,000		8,000,000
Baltimore Gas and Electric Company [Member]
Variable Interest Entity [Line Items]
Other Commitment	263,000,000		263,000,000
Payments for Restructuring			1,000,000
Baltimore Gas and Electric Company [Member] | RSB Bond Co LLC [Member]
Variable Interest Entity [Line Items]
Cash Remitted To VIE	27,000,000	$ 21,000,000	64,000,000	63,000,000
Atlantic City Electric Company [Member]
Variable Interest Entity [Line Items]
Other Commitment	9,000,000		9,000,000
Number Of Variable Interest Entities Consolidated | VIE							1
Due from Affiliates	2,000,000		2,000,000				$ 0
Guarantor Obligations, Maximum Exposure, Undiscounted	13,000,000		13,000,000
Payments for Restructuring			0
Atlantic City Electric Company [Member] | ATF [Member]
Variable Interest Entity [Line Items]
Cash Remitted To VIE	20,000,000	$ 18,000,000	47,000,000	$ 45,000,000
Constellation Energy Nuclear Group [Member] | Exelon Generation Co L L C [Member]
Variable Interest Entity [Line Items]
Due from Affiliates	312,000,000		312,000,000						$ 400,000,000
Severance Benefits Obligations Balance									6,000,000
Financial Guarantee [Member] | Constellation Energy Nuclear Group [Member]
Variable Interest Entity [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted									165,000,000
Payment Guarantee [Member] | Constellation Energy Nuclear Group [Member]
Variable Interest Entity [Line Items]
Payables to affiliates									$ 245,000,000
Equity Method Investment Variable Interest Entities [Member] | Exelon Generation Co L L C [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Guarantor Obligations, Current Carrying Value	$ 637,000,000		$ 637,000,000

Variable Interest Entities - Ca

Variable Interest Entities - Carrying Amounts and Classification of Consolidated VIE Assets and Liabilities (Details) - USD ($) $ in Millions		Sep. 30, 2016		Dec. 31, 2015
Variable Interest Entity [Line Items]
Current Assets	[2]	$ 914	[1]	$ 909
Non Current Assets	[2]	8,235	[1]	8,009
Total Assets	[2]	9,149	[1]	8,918
Current Liabilities	[2]	569	[1]	473
Non Current Liabilities	[2]	3,090	[1]	2,927
Total Liabilities	[2]	3,659	[1]	3,400
Assets		114,535		95,384
Total liabilities	[3]	87,049		68,062
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets		8,514		8,268
Total liabilities		3,438		3,264
Exelon Generation Co L L C [Member]
Variable Interest Entity [Line Items]
Current Assets		849	[1]	881
Non Current Assets		8,201	[1]	8,004
Total Assets		9,050	[1]	8,885
Current Liabilities		439	[1]	387
Non Current Liabilities		2,979	[1]	2,884
Total Liabilities		3,418	[1]	3,271
Assets		47,568		46,529
Total liabilities	[4]	33,829		33,559
Exelon Generation Co L L C [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets		8,415		8,235
Total liabilities		3,196		3,135
Baltimore Gas and Electric Company [Member]
Variable Interest Entity [Line Items]
Current Assets		44		23
Non Current Assets		3		3
Total Assets		47		26
Current Liabilities		84		81
Non Current Liabilities		0		41
Total Liabilities		84		122
Assets	[5]	8,857		8,295
Total liabilities	[5]	6,100		5,418
Baltimore Gas and Electric Company [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets		47		26
Total liabilities		83		122
Pepco Holdings LLC [Member] | Predecessor [Member]
Variable Interest Entity [Line Items]
Current Assets				12
Non Current Assets				18
Total Assets				30
Current Liabilities				48
Non Current Liabilities				124
Total Liabilities				172
Assets				16,188
Total liabilities				11,592
Pepco Holdings LLC [Member] | Successor [Member]
Variable Interest Entity [Line Items]
Current Assets		20
Non Current Assets		31
Total Assets		51
Current Liabilities		45
Non Current Liabilities		111
Total Liabilities		156
Assets		21,063
Total liabilities		13,176
Pepco Holdings LLC [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Predecessor [Member]
Variable Interest Entity [Line Items]
Assets				30
Total liabilities				172
Pepco Holdings LLC [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Successor [Member]
Variable Interest Entity [Line Items]
Assets		51
Total liabilities		156
Atlantic City Electric Company [Member]
Variable Interest Entity [Line Items]
Current Assets		15		12
Non Current Assets		19		18
Total Assets		34		30
Current Liabilities		40		48
Non Current Liabilities		99		124
Total Liabilities		139		172
Assets		3,507		3,387
Total liabilities		2,442		2,387
Atlantic City Electric Company [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets		34		30
Total liabilities		$ 139		$ 172
[1]	.
[2]	Includes certain purchase accounting adjustments not pushed down to the BGE standalone entity.
[3]	Exelon’s consolidated assets include $8,514 million and $8,268 million at September 30, 2016 and December 31, 2015, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Exelon’s consolidated liabilities include $3,438 million and $3,264 million at September 30, 2016 and December 31, 2015, respectively, of certain VIEs for which the VIE creditors do not have recourse to Exelon. See Note 3 - Variable Interest Entities.
[4]	Generation’s consolidated assets include $8,415 million and $8,235 million at September 30, 2016 and December 31, 2015, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Generation’s consolidated liabilities include $3,196 million and $3,135 million at September 30, 2016 and December 31, 2015, respectively, of certain VIEs for which the VIE creditors do not have recourse to Generation. See Note 3 - Variable Interest Entities.
[5]	BGE’s consolidated assets include $47 million and $26 million at September 30, 2016 and December 31, 2015, respectively, of BGE’s consolidated VIE that can only be used to settle the liabilities of the VIE. BGE’s consolidated liabilities include $83 million and $122 million at September 30, 2016 and December 31, 2015, respectively, of BGE’s consolidated VIE for which the VIE creditors do not have recourse to BGE. See Note 3 - Variable Interest Entities.

Variable Interest Entities - As

Variable Interest Entities - Assets and Liabilities of VIES which Creditors or Beneficiaries have no Recourse (Details) - USD ($) $ in Millions		Sep. 30, 2016	Mar. 23, 2016	Dec. 31, 2015		Sep. 30, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Cash and cash equivalents		$ 1,897		$ 6,502		$ 7,265	$ 1,878
Restricted cash		321		205
Accounts receivable, net
Customer		4,061		3,187
Other		1,013		912
Derivative Asset, Current		754		1,365
Inventory
Materials and supplies		1,188		1,104
Other current assets		1,064		752
Total current assets		12,208		15,334
Property, plant and equipment, net		71,214		57,439
Nuclear decommissioning trust funds		11,076		10,342
Goodwill		6,672		2,672
Derivative Asset, Noncurrent		669		758
Other noncurrent assets		1,474		1,445
Total assets		114,535		95,384
Short-term borrowings		567		533
Long-term debt due within one year		2,512		1,500
Accounts payable		3,044		2,883
Accrued expenses		3,236		2,376
Mark-to-market derivative liabilities (current liabilities)		222		205
Other current liabilities		452		100
Other		1,068		842
Total current liabilities		12,158		9,118
Long-term debt		32,330		23,645
Asset retirement obligations		9,348		8,585
Pension obligation(c)		3,765		3,385
Energy Marketing Contract Liabilities, Noncurrent		927		117
Other noncurrent liabilities		1,928		1,491
Total liabilities	[1]	87,049		68,062
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		160		164
Restricted cash		101		100
Accounts receivable, net
Customer		264		219
Other		42		43
Derivative Asset, Current		49		140
Inventory
Materials and supplies		192		181
Other current assets		58		35
Total current assets		866		882
Property, plant and equipment, net		5,139		5,160
Nuclear decommissioning trust funds		2,173		2,036
Goodwill		47		47
Derivative Asset, Noncurrent		32		53
Other noncurrent assets		257		90
Total noncurrent assets		7,648		7,386
Total assets		8,514		8,268
Long-term debt due within one year		191		111
Accounts payable		201		216
Accrued expenses		102		115
Mark-to-market derivative liabilities (current liabilities)		24		5
Other current liabilities		14		12
Other		34		13
Total current liabilities		566		472
Long-term debt		661		666
Asset retirement obligations	[2]	2,070		1,999
Pension obligation(c)		9		9
Energy Marketing Contract Liabilities, Noncurrent		26		39
Other noncurrent liabilities		106		79
Total deferred credits and other liabilities		2,872		2,792
Total liabilities		3,438		3,264
Exelon Generation Co L L C [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		375		431		545	780
Restricted cash		162		123
Accounts receivable, net
Customer		2,318		2,095
Other		301		360
Derivative Asset, Current		754		1,365
Inventory
Materials and supplies		849		880
Other current assets		788		535
Total current assets		6,135		6,342
Property, plant and equipment, net		26,374		25,843
Nuclear decommissioning trust funds		11,076		10,342
Goodwill		47		47
Derivative Asset, Noncurrent		630		733
Other noncurrent assets		692		627
Total assets		47,568		46,529
Short-term borrowings		40		29
Long-term debt due within one year		254		90
Accounts payable		1,465		1,583
Accrued expenses		942		935
Mark-to-market derivative liabilities (current liabilities)		203		182
Other current liabilities		76		100
Other		392		356
Total current liabilities		4,307		4,933
Long-term debt		8,077		7,936
Asset retirement obligations		9,160		8,431
Energy Marketing Contract Liabilities, Noncurrent		97		117
Other noncurrent liabilities		691		602
Total liabilities	[3]	33,829		33,559
Exelon Generation Co L L C [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		160		164
Restricted cash		43		77
Accounts receivable, net
Customer		264		219
Other		42		43
Derivative Asset, Current		49		140
Inventory
Materials and supplies		192		181
Other current assets		51		30
Total current assets		801		854
Property, plant and equipment, net		5,139		5,160
Nuclear decommissioning trust funds		2,173		2,036
Goodwill		47		47
Derivative Asset, Noncurrent		32		53
Other noncurrent assets		223		85
Total noncurrent assets		7,614		7,381
Total assets		8,415		8,235
Long-term debt due within one year		64		27
Accounts payable		201		216
Accrued expenses		98		113
Mark-to-market derivative liabilities (current liabilities)		24		5
Other current liabilities		14		12
Other		34		13
Total current liabilities		435		386
Long-term debt		550		623
Asset retirement obligations		2,070		1,999	[2]
Pension obligation(c)		9		9
Energy Marketing Contract Liabilities, Noncurrent		26		39
Other noncurrent liabilities		106		79
Total deferred credits and other liabilities		2,761		2,749
Total liabilities		3,196		3,135
Baltimore Gas and Electric Company [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		341		9		27	64
Restricted cash		46		24
Accounts receivable, net
Customer		332		300
Other		100		112
Inventory
Materials and supplies		39		33
Other current assets		5		3
Total current assets		1,114		845
Property, plant and equipment, net		6,904		6,597
Other noncurrent assets		9		8
Total assets	[4]	8,857		8,295
Short-term borrowings		0		210
Long-term debt due within one year		381		378
Accounts payable		239		209
Accrued expenses		144		110
Other		35		35
Total current liabilities		1,003		1,134
Long-term debt		2,281		1,480
Asset retirement obligations		21		17
Other noncurrent liabilities		72		61
Total liabilities	[4]	6,100		5,418
Baltimore Gas and Electric Company [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		0		0
Restricted cash		44		23
Accounts receivable, net
Customer		0		0
Other		0		0
Derivative Asset, Current		0		0
Inventory
Materials and supplies		0		0
Other current assets		0		0
Total current assets		44		23
Property, plant and equipment, net		0		0
Nuclear decommissioning trust funds		0		0
Goodwill		0		0
Derivative Asset, Noncurrent		0		0
Other noncurrent assets		3		3
Total noncurrent assets		3		3
Total assets		47		26
Long-term debt due within one year		81		79
Accounts payable		0		0
Accrued expenses		2		2
Mark-to-market derivative liabilities (current liabilities)		0		0
Other current liabilities		0		0
Other		0		0
Total current liabilities		83		81
Long-term debt				41
Asset retirement obligations		0		0
Pension obligation(c)	[2]	0		0
Energy Marketing Contract Liabilities, Noncurrent		0		0
Other noncurrent liabilities		0		0
Total deferred credits and other liabilities		0		41
Total liabilities		83		122
Pepco Holdings LLC [Member]
Inventory
Goodwill		4,000		0
Pepco Holdings LLC [Member] | Predecessor [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents			$ 319	26		272	15
Restricted cash				14
Accounts receivable, net
Customer				581
Other				319
Derivative Asset, Current				18
Inventory
Materials and supplies				122
Other current assets				80
Total current assets				1,474
Property, plant and equipment, net				10,864
Goodwill				1,406
Derivative Asset, Noncurrent				0
Other noncurrent assets				69
Total assets				16,188
Short-term borrowings				958
Long-term debt due within one year				456
Accounts payable				404
Accrued expenses				266
Mark-to-market derivative liabilities (current liabilities)				0
Other current liabilities				0
Other				70
Total current liabilities				2,327
Long-term debt				4,823
Asset retirement obligations				8
Pension obligation(c)				466
Energy Marketing Contract Liabilities, Noncurrent				0
Other noncurrent liabilities				200
Total liabilities				11,592
Pepco Holdings LLC [Member] | Successor [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		299	$ 319
Restricted cash		49
Accounts receivable, net
Customer		595
Other		345
Derivative Asset, Current		0
Inventory
Materials and supplies		118
Other current assets		54
Total current assets		2,118
Property, plant and equipment, net		11,311
Goodwill		4,000
Derivative Asset, Noncurrent		0
Other noncurrent assets		76
Total assets		21,063
Short-term borrowings		517
Long-term debt due within one year		545
Accounts payable		335
Accrued expenses		325
Mark-to-market derivative liabilities (current liabilities)		0
Other current liabilities		376
Other		36
Total current liabilities		2,547
Long-term debt		5,499
Asset retirement obligations		14
Pension obligation(c)		0
Energy Marketing Contract Liabilities, Noncurrent		830
Other noncurrent liabilities		234
Total liabilities		13,176
Pepco Holdings LLC [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Predecessor [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents				0
Restricted cash				12
Accounts receivable, net
Customer				0
Other				0
Derivative Asset, Current				0
Inventory
Materials and supplies				0
Other current assets				0
Total current assets				12
Property, plant and equipment, net				0
Nuclear decommissioning trust funds				0
Goodwill				0
Derivative Asset, Noncurrent				0
Other noncurrent assets				18
Total noncurrent assets				18
Total assets				30
Long-term debt due within one year				46
Accounts payable				0
Accrued expenses				2
Mark-to-market derivative liabilities (current liabilities)				0
Other current liabilities				0
Other				0
Total current liabilities				48
Long-term debt				124
Asset retirement obligations				0
Pension obligation(c)	[2]			0
Energy Marketing Contract Liabilities, Noncurrent				0
Other noncurrent liabilities				0
Total deferred credits and other liabilities				124
Total liabilities				172
Pepco Holdings LLC [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Successor [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		0
Restricted cash		15
Accounts receivable, net
Customer		0
Other		0
Derivative Asset, Current		0
Inventory
Materials and supplies		0
Other current assets		5
Total current assets		20
Property, plant and equipment, net		0
Nuclear decommissioning trust funds		0
Goodwill		0
Derivative Asset, Noncurrent		0
Other noncurrent assets		31
Total noncurrent assets		31
Total assets		51
Long-term debt due within one year		43
Accounts payable		0
Accrued expenses		2
Mark-to-market derivative liabilities (current liabilities)		0
Other current liabilities		0
Other		0
Total current liabilities		45
Long-term debt		111
Asset retirement obligations		0
Pension obligation(c)	[2]	0
Energy Marketing Contract Liabilities, Noncurrent		0
Other noncurrent liabilities		0
Total deferred credits and other liabilities		111
Total liabilities		156
Atlantic City Electric Company [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		165		3		$ 4	$ 2
Restricted cash		15		12
Accounts receivable, net
Customer		168		156
Other		46		242
Inventory
Materials and supplies		22		23
Other current assets		3		12
Total current assets		520		546
Property, plant and equipment, net		2,456		2,322
Other noncurrent assets		42		19
Total assets		3,507		3,387
Short-term borrowings		0		5
Long-term debt due within one year		38		48
Accounts payable		110		96
Accrued expenses		72		70
Other		7		14
Total current liabilities		338		297
Long-term debt		1,129		1,153
Other noncurrent liabilities		31		12
Total liabilities		2,442		2,387
Atlantic City Electric Company [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		0		0
Restricted cash		15		12
Accounts receivable, net
Customer		0		0
Other		0		0
Derivative Asset, Current		0		0
Inventory
Materials and supplies		0		0
Other current assets		0		0
Total current assets		15		12
Property, plant and equipment, net		0		0
Nuclear decommissioning trust funds		0		0
Goodwill		0		0
Derivative Asset, Noncurrent		0		0
Other noncurrent assets		19		18
Total noncurrent assets		19		18
Total assets		34		30
Long-term debt due within one year		38		46
Accounts payable		0		0
Accrued expenses		2		2
Mark-to-market derivative liabilities (current liabilities)		0		0
Other current liabilities		0		0
Other		0		0
Total current liabilities		40		48
Long-term debt		99		124
Asset retirement obligations		0		0
Pension obligation(c)	[2]	0		0
Energy Marketing Contract Liabilities, Noncurrent		0		0
Other noncurrent liabilities		0		0
Total deferred credits and other liabilities		99		124
Total liabilities		$ 139		$ 172
[1]	Exelon’s consolidated assets include $8,514 million and $8,268 million at September 30, 2016 and December 31, 2015, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Exelon’s consolidated liabilities include $3,438 million and $3,264 million at September 30, 2016 and December 31, 2015, respectively, of certain VIEs for which the VIE creditors do not have recourse to Exelon. See Note 3 - Variable Interest Entities.
[2]	Includes the CNEG retail gas pension obligation, which is presented as a net asset balance within the Prepaid pension asset line item on Generation’s balance sheet. See Note 13 - Retirement Benefits for additional details.
[3]	Generation’s consolidated assets include $8,415 million and $8,235 million at September 30, 2016 and December 31, 2015, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Generation’s consolidated liabilities include $3,196 million and $3,135 million at September 30, 2016 and December 31, 2015, respectively, of certain VIEs for which the VIE creditors do not have recourse to Generation. See Note 3 - Variable Interest Entities.
[4]	BGE’s consolidated assets include $47 million and $26 million at September 30, 2016 and December 31, 2015, respectively, of BGE’s consolidated VIE that can only be used to settle the liabilities of the VIE. BGE’s consolidated liabilities include $83 million and $122 million at September 30, 2016 and December 31, 2015, respectively, of BGE’s consolidated VIE for which the VIE creditors do not have recourse to BGE. See Note 3 - Variable Interest Entities.

Variable Interest Entities - Su

Variable Interest Entities - Summary of Significant Unconsolidated VIEs (Details) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Total assets	[1]	$ 1,117	$ 427
Total liabilities	[1]	489	147
Exelon's ownership interest in VIE	[1]	193	11
Other ownership interests in VIE	[1]	439	269
Assets Held-in-trust, Noncurrent		135	206
Commercial Agreement Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Total assets	[1]	586	263
Total liabilities	[1]	181	22
Exelon's ownership interest in VIE	[1]	0	0
Other ownership interests in VIE	[1]	405	241
Equity Method Investment Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Total assets	[1]	531	164
Total liabilities	[1]	308	125
Exelon's ownership interest in VIE	[1]	193	11
Other ownership interests in VIE	[1]	34	28
Investments [Member]
Variable Interest Entity [Line Items]
Registrants' maximum exposure to loss		225
Investments [Member] | Maximum [Member]
Variable Interest Entity [Line Items]
Registrants' maximum exposure to loss			21
Investments [Member] | Maximum [Member] | Commercial Agreement Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Registrants' maximum exposure to loss		0	0
Investments [Member] | Maximum [Member] | Equity Method Investment Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Registrants' maximum exposure to loss		225	21
Contract Intangible Asset [Member] | Maximum [Member]
Variable Interest Entity [Line Items]
Registrants' maximum exposure to loss		9	9
Contract Intangible Asset [Member] | Maximum [Member] | Commercial Agreement Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Registrants' maximum exposure to loss		9	9
Contract Intangible Asset [Member] | Maximum [Member] | Equity Method Investment Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Registrants' maximum exposure to loss		0
Payment Guarantee [Member]
Variable Interest Entity [Line Items]
Registrants' maximum exposure to loss		3
Payment Guarantee [Member] | Maximum [Member]
Variable Interest Entity [Line Items]
Registrants' maximum exposure to loss			3
Payment Guarantee [Member] | Maximum [Member] | Commercial Agreement Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Registrants' maximum exposure to loss		0
Payment Guarantee [Member] | Maximum [Member] | Equity Method Investment Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Registrants' maximum exposure to loss		3	3
Asset Held In Trust Noncurrent [Member] | Maximum [Member]
Variable Interest Entity [Line Items]
Registrants' maximum exposure to loss	[2]	11	17
Asset Held In Trust Noncurrent [Member] | Maximum [Member] | Commercial Agreement Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Registrants' maximum exposure to loss	[2]	11	17
Asset Held In Trust Noncurrent [Member] | Maximum [Member] | Equity Method Investment Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Registrants' maximum exposure to loss	[2]	0
Exelon Generation Co L L C [Member]
Variable Interest Entity [Line Items]
Assets Held-in-trust, Noncurrent		135	206
Payable to Zion Solutions	[3]	124	$ 189
Exelon Generation Co L L C [Member] | Investments [Member] | Maximum [Member]
Variable Interest Entity [Line Items]
Registrants' maximum exposure to loss		$ 20
[1]	These items represent amounts on the unconsolidated VIE balance sheets, not on Exelon’s or Generation’s Consolidated Balance Sheets. These items are included to provide information regarding the relative size of the unconsolidated VIEs.
[2]	These items represent amounts on Exelon’s and Generation’s Consolidated Balance Sheets related to the asset sale agreement with ZionSolutions, LLC. The net assets pledged for Zion Station decommissioning includes gross pledged assets of $135 million and $206 million as of September 30, 2016 and December 31, 2015, respectively; offset by payables to ZionSolutions LLC of $124 million and $189 million as of September 30, 2016 and December 31, 2015, respectively. These items are included to provide information regarding the relative size of the ZionSolutions LLC unconsolidated VIE.
[3]	Excludes a liability recorded within Exelon’s and Generation’s Consolidated Balance Sheets related to the tax obligation on the unrealized activity associated with the Zion Station NDT funds. The NDT funds will be utilized to satisfy the tax obligations as gains and losses are realized.

Mergers, Acquisitions, and Di51

Mergers, Acquisitions, and Dispositions - Narrative (Details) - USD ($)	Mar. 31, 2016	Jul. 31, 2016	Mar. 31, 2017	Sep. 30, 2016	Jun. 30, 2016	Mar. 23, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Aug. 31, 2016	Mar. 24, 2016	Jul. 31, 2014
Business Acquisition [Line Items]
Revenues				$ 9,002,000,000			$ 7,401,000,000		$ 23,486,000,000	$ 22,746,000,000
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Payments to Acquire Businesses, Gross									(6,896,000,000)	(28,000,000)
Business Combination, Integration Related Costs				20,000,000			22,000,000		123,000,000	84,000,000
Investments				$ 592,000,000				$ 592,000,000	$ 592,000,000		$ 639,000,000
Cash offered in exchange for each share of PHI stock				$ 27.25				$ 27.25	$ 27.25
Other noncurrent assets				$ 1,474,000,000				$ 1,474,000,000	$ 1,474,000,000		1,445,000,000
Other Commitment	$ 508,000,000			6,497,000,000				6,497,000,000	6,497,000,000			$ 513,000,000
Business Combination, Contingent Consideration, Asset				235,000,000				235,000,000	235,000,000
Net income				526,000,000			587,000,000		956,000,000	1,959,000,000
Goodwill, Acquired During Period						$ (4,016,000,000)			16,000,000
Net Working Capital									96,000,000
Other Intangible Assets [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Finite-lived Intangible Assets Acquired									1,500,000,000
Common Stock [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Payments to Acquire Businesses, Gross											(180,000,000)
Other Investments [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Other Commitment				137,000,000				137,000,000	137,000,000
Other Investments [Member] | Scenario, Adjustment [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Other Commitment				55,000,000				55,000,000	55,000,000
Pepco Holdings LLC [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent				3,442,000,000				3,442,000,000	3,442,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets				1,441,000,000				1,441,000,000	1,441,000,000
Revenues				1,437,000,000					2,656,000,000
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Other Commitment				513,000,000				513,000,000	513,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets				4,000,000,000				4,000,000,000	4,000,000,000
Net income				169,000,000					(92,000,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Assets				248,000,000				248,000,000	248,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities				2,752,000,000				2,752,000,000	2,752,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt				5,636,000,000				5,636,000,000	5,636,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other				187,000,000				187,000,000	187,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment				11,088,000,000				11,088,000,000	11,088,000,000
Pepco Holdings LLC [Member] | Common Stock [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Payments to Acquire Businesses, Gross									(6,933,000,000)
Pepco Holdings LLC [Member] | Common Stock [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Payments to Acquire Businesses, Gross									(180,000,000)
Pepco Holdings LLC [Member] | Successor [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Payments to Acquire Businesses, Gross					$ (33,000,000)			(62,000,000)
PEPCO Holdings Inc [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Payments to Acquire Businesses, Gross									(7,142,000,000)
PEPCO Holdings Inc [Member] | Other Investments [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Other Commitment				444,000,000				444,000,000	444,000,000
ConEdision [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Business Combination, Consideration Transferred, Liabilities Incurred									22,000,000
Fitzpatrick [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Payments to Acquire Businesses, Gross				(110,000,000)
Fitzpatrick [Member] | Maximum [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Business Combination, Integration Related Costs			$ 250,000,000
Exelon Generation Co L L C [Member]
Business Acquisition [Line Items]
Revenues				5,035,000,000			4,768,000,000		13,363,000,000	14,841,000,000
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Payments to Acquire Businesses, Gross									(255,000,000)	(28,000,000)
Business Combination, Integration Related Costs				9,000,000			10,000,000		29,000,000	30,000,000
Investments				$ 381,000,000				$ 381,000,000	$ 381,000,000		210,000,000
Equity Method Investment, Ownership Percentage				50.01%				50.01%	50.01%
Other noncurrent assets				$ 692,000,000				$ 692,000,000	$ 692,000,000		627,000,000
Gain (Loss) on Disposition of Property Plant Equipment									32,000,000
Other Commitment				5,679,000,000				5,679,000,000	5,679,000,000					$ 91,000,000
Business Combination, Contingent Consideration, Asset				163,000,000				163,000,000	163,000,000
Net income				271,000,000			332,000,000		556,000,000	1,208,000,000
Members' Capital				9,265,000,000				9,265,000,000	9,265,000,000		8,997,000,000
Exelon Generation Co L L C [Member] | ConEdision [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Payments to Acquire Businesses, Gross				(257,000,000)					(235,000,000)
Net Working Capital				204,000,000
Atlantic City Electric Company [Member]
Business Acquisition [Line Items]
Revenues				421,000,000			386,000,000		982,000,000	1,003,000,000
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Business Combination, Integration Related Costs				2,000,000			0		17,000,000	1,000,000
Other noncurrent assets				42,000,000				42,000,000	42,000,000		19,000,000
Other Commitment				9,000,000				9,000,000	9,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets				1,158,000,000				1,158,000,000	1,158,000,000
Net income				47,000,000			22,000,000		(50,000,000)	37,000,000
Atlantic City Electric Company [Member] | Other Investments [Member] | Scenario, Adjustment [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Other Commitment				10,000,000				10,000,000	10,000,000
Atlantic City Electric Company [Member] | Pepco Holdings LLC [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Other Commitment				111,000,000				111,000,000	111,000,000
Equity Contribution									49,000,000
Potomac Electric Power Company [Member]
Business Acquisition [Line Items]
Revenues				635,000,000			592,000,000		1,695,000,000	1,641,000,000
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Investments				100,000,000				100,000,000	100,000,000		68,000,000
Other noncurrent assets				4,000,000				4,000,000	4,000,000		4,000,000
Gain (Loss) on Disposition of Property Plant Equipment									8,000,000
Other Commitment				15,000,000				15,000,000	15,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets				1,683,000,000				1,683,000,000	1,683,000,000
Net income				79,000,000			60,000,000		20,000,000	128,000,000
Potomac Electric Power Company [Member] | Successor [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Payments to Acquire Businesses, Gross									(33,000,000)
Potomac Electric Power Company [Member] | Other Investments [Member] | Scenario, Adjustment [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Other Commitment				13,000,000				13,000,000	13,000,000
Potomac Electric Power Company [Member] | Pepco Holdings LLC [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Other Commitment				126,000,000				126,000,000	126,000,000
Equity Contribution									73,000,000
Delmarva Power and Light Company [Member]
Business Acquisition [Line Items]
Revenues				331,000,000			314,000,000		974,000,000	1,004,000,000
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Business Combination, Integration Related Costs				2,000,000			0		18,000,000	2,000,000
Other noncurrent assets				7,000,000				7,000,000	7,000,000		$ 2,000,000
Gain (Loss) on Disposition of Property Plant Equipment		$ 4,000,000
Other Commitment				11,000,000				11,000,000	11,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets				1,128,000,000				1,128,000,000	1,128,000,000
Net income				44,000,000			15,000,000		(16,000,000)	55,000,000
Delmarva Power and Light Company [Member] | Other Investments [Member] | Scenario, Adjustment [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Other Commitment				27,000,000				27,000,000	27,000,000
Delmarva Power and Light Company [Member] | Pepco Holdings LLC [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Other Commitment				77,000,000				77,000,000	77,000,000
Equity Contribution									46,000,000
Pepco Holdings LLC [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Business Combination, Integration Related Costs				3,000,000			$ 1,000,000		26,000,000	$ 3,000,000
Goodwill, Acquired During Period						$ (4,016,000,000)
Pepco Holdings LLC [Member] | Scenario, Adjustment [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Fresh-Start Adjustment, Increase (Decrease), Deferred Income Tax Liabilities, Noncurrent													$ 59,000,000
Pepco Holdings LLC [Member] | Successor [Member]
Business Acquisition [Line Items]
Revenues				1,394,000,000				2,565,000,000
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Business Combination, Integration Related Costs	$ 63,000,000			7,000,000
Investments				132,000,000				132,000,000	132,000,000
Other noncurrent assets				76,000,000				76,000,000	76,000,000
Business Combination, Contingent Consideration, Asset													301,000,000
Net income				166,000,000				(91,000,000)
Members' Capital				7,978,000,000				7,978,000,000	7,978,000,000				$ 7,200,000,000
Pepco Holdings LLC [Member] | Other Investments [Member] | Scenario, Adjustment [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Other Commitment				50,000,000				50,000,000	50,000,000
Pepco Holdings LLC [Member] | Pepco Holdings LLC [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Other Commitment				314,000,000				314,000,000	314,000,000
Constellation Energy Group LLC [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Total liabilities held for sale (b)				5,000,000				5,000,000	5,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment				$ 46,000,000				$ 46,000,000	$ 46,000,000
Subsequent Event [Member] | Fitzpatrick [Member] | Minimum [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Business Combination, Integration Related Costs			$ 200,000,000

Mergers, Acquisitions, and Di52

Mergers, Acquisitions, and Dispositions Merger Commitments Table (Details) - USD ($)	Sep. 30, 2016	Aug. 31, 2016	Mar. 31, 2016
Other Commitments [Line Items]
Other Commitment	$ 6,497,000,000	$ 513,000,000	$ 508,000,000
Potomac Electric Power Company [Member]
Other Commitments [Line Items]
Other Commitment	15,000,000
Delmarva Power and Light Company [Member]
Other Commitments [Line Items]
Other Commitment	11,000,000
Atlantic City Electric Company [Member]
Other Commitments [Line Items]
Other Commitment	9,000,000
Pepco Holdings LLC [Member]
Other Commitments [Line Items]
Other Commitment	513,000,000
Pepco Holdings LLC [Member] | Pepco Holdings LLC [Member]
Other Commitments [Line Items]
Other Commitment	314,000,000
Pepco Holdings LLC [Member] | Potomac Electric Power Company [Member]
Other Commitments [Line Items]
Other Commitment	126,000,000
Pepco Holdings LLC [Member] | Delmarva Power and Light Company [Member]
Other Commitments [Line Items]
Other Commitment	77,000,000
Pepco Holdings LLC [Member] | Atlantic City Electric Company [Member]
Other Commitments [Line Items]
Other Commitment	111,000,000
Pepco Holdings LLC [Member] | Rate Bill Credits [Member]
Other Commitments [Line Items]
Other Commitment	250,000,000
Pepco Holdings LLC [Member] | Rate Bill Credits [Member] | Pepco Holdings LLC [Member]
Other Commitments [Line Items]
Other Commitment	250,000,000
Pepco Holdings LLC [Member] | Rate Bill Credits [Member] | Potomac Electric Power Company [Member]
Other Commitments [Line Items]
Other Commitment	91,000,000
Pepco Holdings LLC [Member] | Rate Bill Credits [Member] | Delmarva Power and Light Company [Member]
Other Commitments [Line Items]
Other Commitment	58,000,000
Pepco Holdings LLC [Member] | Rate Bill Credits [Member] | Atlantic City Electric Company [Member]
Other Commitments [Line Items]
Other Commitment	101,000,000
Pepco Holdings LLC [Member] | Energy Efficiency Program [Member]
Other Commitments [Line Items]
Other Commitment	120,000,000
Pepco Holdings LLC [Member] | Energy Efficiency Program [Member] | Pepco Holdings LLC [Member]
Other Commitments [Line Items]
Other Commitment	0
Pepco Holdings LLC [Member] | Energy Efficiency Program [Member] | Potomac Electric Power Company [Member]
Other Commitments [Line Items]
Other Commitment	0
Pepco Holdings LLC [Member] | Energy Efficiency Program [Member] | Delmarva Power and Light Company [Member]
Other Commitments [Line Items]
Other Commitment	0
Pepco Holdings LLC [Member] | Energy Efficiency Program [Member] | Atlantic City Electric Company [Member]
Other Commitments [Line Items]
Other Commitment	0
Pepco Holdings LLC [Member] | Charitable Contributions [Member]
Other Commitments [Line Items]
Other Commitment	50,000,000
Pepco Holdings LLC [Member] | Charitable Contributions [Member] | Pepco Holdings LLC [Member]
Other Commitments [Line Items]
Other Commitment	50,000,000
Pepco Holdings LLC [Member] | Charitable Contributions [Member] | Potomac Electric Power Company [Member]
Other Commitments [Line Items]
Other Commitment	28,000,000
Pepco Holdings LLC [Member] | Charitable Contributions [Member] | Delmarva Power and Light Company [Member]
Other Commitments [Line Items]
Other Commitment	12,000,000
Pepco Holdings LLC [Member] | Charitable Contributions [Member] | Atlantic City Electric Company [Member]
Other Commitments [Line Items]
Other Commitment	10,000,000
Pepco Holdings LLC [Member] | Delivery System Modernization [Member]
Other Commitments [Line Items]
Other Commitment	22,000,000
Pepco Holdings LLC [Member] | Delivery System Modernization [Member] | Pepco Holdings LLC [Member]
Other Commitments [Line Items]
Other Commitment	0
Pepco Holdings LLC [Member] | Delivery System Modernization [Member] | Potomac Electric Power Company [Member]
Other Commitments [Line Items]
Other Commitment	0
Pepco Holdings LLC [Member] | Delivery System Modernization [Member] | Delmarva Power and Light Company [Member]
Other Commitments [Line Items]
Other Commitment	0
Pepco Holdings LLC [Member] | Delivery System Modernization [Member] | Atlantic City Electric Company [Member]
Other Commitments [Line Items]
Other Commitment	0
Pepco Holdings LLC [Member] | Green Sustainability Fund [Member]
Other Commitments [Line Items]
Other Commitment	14,000,000
Pepco Holdings LLC [Member] | Green Sustainability Fund [Member] | Pepco Holdings LLC [Member]
Other Commitments [Line Items]
Other Commitment	0
Pepco Holdings LLC [Member] | Green Sustainability Fund [Member] | Potomac Electric Power Company [Member]
Other Commitments [Line Items]
Other Commitment	0
Pepco Holdings LLC [Member] | Green Sustainability Fund [Member] | Delmarva Power and Light Company [Member]
Other Commitments [Line Items]
Other Commitment	0
Pepco Holdings LLC [Member] | Green Sustainability Fund [Member] | Atlantic City Electric Company [Member]
Other Commitments [Line Items]
Other Commitment	0
Pepco Holdings LLC [Member] | Workforce Development [Member]
Other Commitments [Line Items]
Other Commitment	24,000,000
Pepco Holdings LLC [Member] | Workforce Development [Member] | Pepco Holdings LLC [Member]
Other Commitments [Line Items]
Other Commitment	0
Pepco Holdings LLC [Member] | Workforce Development [Member] | Potomac Electric Power Company [Member]
Other Commitments [Line Items]
Other Commitment	0
Pepco Holdings LLC [Member] | Workforce Development [Member] | Delmarva Power and Light Company [Member]
Other Commitments [Line Items]
Other Commitment	0
Pepco Holdings LLC [Member] | Workforce Development [Member] | Atlantic City Electric Company [Member]
Other Commitments [Line Items]
Other Commitment	0
Pepco Holdings LLC [Member] | Other1 [Member]
Other Commitments [Line Items]
Other Commitment	33,000,000
Pepco Holdings LLC [Member] | Other1 [Member] | Pepco Holdings LLC [Member]
Other Commitments [Line Items]
Other Commitment	14,000,000
Pepco Holdings LLC [Member] | Other1 [Member] | Potomac Electric Power Company [Member]
Other Commitments [Line Items]
Other Commitment	7,000,000
Pepco Holdings LLC [Member] | Other1 [Member] | Delmarva Power and Light Company [Member]
Other Commitments [Line Items]
Other Commitment	7,000,000
Pepco Holdings LLC [Member] | Other1 [Member] | Atlantic City Electric Company [Member]
Other Commitments [Line Items]
Other Commitment	$ 0

Mergers, Acquisitions, and Di53

Mergers, Acquisitions, and Dispositions Merger Transaction Table (Details) - USD ($) $ / shares in Units, shares in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Business Acquisition, Share Price	$ 27.25
Investments	$ 592,000,000		$ 639,000,000
Shares, Issued	958,014		954,668
Payments to Acquire Businesses, Gross	$ 6,896,000,000	$ 28,000,000
Preferred Stock [Member]
Payments to Acquire Businesses, Gross			$ 180,000,000
Pepco Holdings LLC [Member] | Common Stock [Member]
Payments to Acquire Businesses, Gross	6,933,000,000
Pepco Holdings LLC [Member] | Preferred Stock [Member]
Payments to Acquire Businesses, Gross	180,000,000
Pepco Holdings LLC [Member] | Deferred Compensation, Share-based Payments [Member]
Payments to Acquire Businesses, Gross	$ 29,000,000

Mergers, Acquisitions, and Di54

Mergers, Acquisitions, and Dispositions Purchase Price Allocation Table (Details) $ in Millions	9 Months Ended
	Sep. 30, 2016USD ($)
Pepco Holdings LLC [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets	$ 1,441
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	11,088
BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRegulatedAssets	5,015
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Assets	248
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	21,792
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities	2,752
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Financial Liabilities	(1,515)
BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRegulatedLiabilities	297
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	5,636
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other	187
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	(14,650)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	7,142
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets	4,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent	3,442
_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRetirmentObligations	821
ConEdison Solutions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets	204
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	322
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Financial Liabilities	(65)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	(65)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	257
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets	100
Business Combination, Consideration Transferred	257
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Derivative Assets	6
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other	1
Potomac Electric Power Company [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets	1,683
Delmarva Power and Light Company [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets	$ 1,128

Mergers, Acquisitions, and Di55

Mergers, Acquisitions, and Dispositions Goodwill Amortization Schedule (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 23, 2016	Sep. 30, 2016	Dec. 31, 2015
Goodwill [Line Items]
Goodwill		$ 6,672	$ 2,672
Goodwill, Acquired During Period	$ 4,016	(16)
Goodwill, Other Increase (Decrease)		(16)
Exelon Generation Co L L C [Member]
Goodwill [Line Items]
Goodwill		47	47
Pepco Holdings LLC [Member]
Goodwill [Line Items]
Goodwill		4,000	$ 0
Goodwill, Acquired During Period	$ 4,016
Goodwill, Other Increase (Decrease)		$ (16)

Mergers, Acquisitions, and Di56

Mergers, Acquisitions, and Dispositions ProForma Impact of Merger (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Business Acquisition, Pro Forma Revenue		$ 9,002	$ 8,545	$ 24,468	$ 26,129	$ 33,823
Business Acquisition, Pro Forma Net Income (Loss)		$ 501	$ 746	$ 1,346	$ 2,169	$ 2,618
Business Acquisition, Pro Forma Earnings Per Share, Basic		$ 0.5416	$ 0.8118	$ 1.4567	$ 2.3602	$ 2.8487
Business Acquisition, Pro Forma Earnings Per Share, Diluted		$ 0.5405	$ 0.8074	$ 1.4536	$ 2.3499	$ 2.8364
Noncash Merger Related Costs	[1],[2]			$ 508
Consolidation, Eliminations [Member]
Business Acquisition, Pro Forma Revenue	[3]		$ 192	171	$ 426	$ 559
Noncash Merger Related Costs	[3]	$ 20	$ 25	$ 660	$ 100	$ 92
[1]	(e)Excludes $5 million of forgiveness of Accounts receivable related to merger commitments recorded in connection with the PHI Merger, the balance is included within Provision for uncollectible accounts.
[2]	See Note 4 — Mergers, Acquisitions and Dispositions for additional information related to the merger with PHI.
[3]	(a)The amounts above include adjustments for non-recurring costs directly related to the merger of $20 million and $660 million for the three and nine months ended September 30, 2016, respectively, and intercompany revenue of $171 million for the nine months ended September 30, 2016.

Mergers, Acquisitions, and Di57

Mergers, Acquisitions, and Dispositions Merger Integration Related Costs Table (Details) - USD ($) $ in Millions	Mar. 31, 2016	Sep. 30, 2016	Mar. 23, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Business Combination, Integration Related Costs		$ 20		$ 22	$ 123	$ 84
Exelon Generation Co L L C [Member]
Business Combination, Integration Related Costs		9		10	29	30
Commonwealth Edison Co [Member]
Business Combination, Integration Related Costs		0		3	(6)	9
PECO Energy Co [Member]
Business Combination, Integration Related Costs		1		1	3	4
Baltimore Gas and Electric Company [Member]
Business Combination, Integration Related Costs		1		2	(3)	4
Pepco Holdings LLC [Member]
Business Combination, Integration Related Costs		3		1	26	3
Delmarva Power and Light Company [Member]
Business Combination, Integration Related Costs		2		0	18	2
Atlantic City Electric Company [Member]
Business Combination, Integration Related Costs		2		0	17	1
Successor [Member] | Pepco Holdings LLC [Member]
Business Combination, Integration Related Costs	$ 63	$ 7
Predecessor [Member] | Pepco Holdings LLC [Member]
Business Combination, Integration Related Costs			$ 29	$ 3		$ 16
Regulatory Assets [Member] | Commonwealth Edison Co [Member]
Business Combination, Integration Related Costs					8
Regulatory Assets [Member] | Baltimore Gas and Electric Company [Member]
Business Combination, Integration Related Costs					6
Regulatory Assets [Member] | Pepco Holdings LLC [Member]
Business Combination, Integration Related Costs					13
Regulatory Assets [Member] | Potomac Electric Power Company [Member]
Business Combination, Integration Related Costs					10
Regulatory Assets [Member] | Delmarva Power and Light Company [Member]
Business Combination, Integration Related Costs					$ 3

Regulatory Matters - Narrative

Regulatory Matters - Narrative (Details)		Jun. 03, 2016USD ($)	Apr. 30, 2012MW	May 31, 2014USD ($)	Sep. 30, 2016USD ($)		Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Sep. 30, 2015USD ($)	Jun. 30, 2016USD ($)	Sep. 30, 2016USD ($)		Sep. 30, 2015USD ($)	Aug. 31, 2016USD ($)	Dec. 31, 2015USD ($)		Jul. 31, 2014USD ($)	Aug. 31, 2010USD ($)
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					$ 11,432,000,000						$ 11,432,000,000				$ 6,824,000,000
Business Combination, Integration Related Costs					20,000,000				$ 22,000,000		123,000,000		$ 84,000,000
Capital Expenditures Incurred but Not yet Paid											338,000,000		59,000,000
Regulatory Liabilities					4,985,000,000						4,985,000,000				4,570,000,000
Regulatory assets					10,022,000,000						10,022,000,000				6,065,000,000
Regulatory Liability, Current					548,000,000						548,000,000				369,000,000
Other Commitment					6,497,000,000			$ 508,000,000			6,497,000,000			$ 513,000,000
Fair Value, Net Asset (Liability)					2,400,000,000						2,400,000,000
Commonwealth Edison Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					1,192,000,000						1,192,000,000				1,113,000,000
Business Combination, Integration Related Costs					0				3,000,000		(6,000,000)		9,000,000
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount											94,000,000
Capital Expenditures Incurred but Not yet Paid											42,000,000		$ 62,000,000
Regulatory Liabilities					3,781,000,000						3,781,000,000				3,614,000,000
Public Utilities, Requested Rate Increase (Decrease), Amount											$ 90,000,000
Approved ROE											11.50%
Public Utilities, Requested Rate Increase (Decrease), Percentage											8.64%		8.59%
Regulatory assets					987,000,000						$ 987,000,000				895,000,000
Regulatory Liability, Current					204,000,000						204,000,000				155,000,000
Other Commitment					226,000,000						226,000,000
Commonwealth Edison Co [Member] | Electric Distribution [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount											138,000,000
Public Utilities, Requested Rate Increase (Decrease), Amount											139,000,000
Public Utilities, Approved Rate Increase (Decrease), Amount											$ 1,000,000
Requested Debt and Equity Return on Distribution											6.71%		6.69%
ICC Approved Rate Increase (Decrease), Amount											$ 1,000,000
PECO Energy Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					1,688,000,000						1,688,000,000				1,617,000,000
Business Combination, Integration Related Costs					1,000,000				1,000,000		3,000,000		$ 4,000,000
Capital Expenditures Incurred but Not yet Paid											4,000,000		(23,000,000)
Regulatory Liabilities					679,000,000						679,000,000				639,000,000
Regulatory assets					1,651,000,000						1,651,000,000				1,583,000,000
Regulatory Liability, Current					128,000,000						128,000,000				112,000,000
Other Commitment					210,000,000						210,000,000
Baltimore Gas and Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					722,000,000						722,000,000				781,000,000
Business Combination, Integration Related Costs					1,000,000				2,000,000		(3,000,000)		4,000,000
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount											28,000,000
Customer Refund Liability, Noncurrent					30,000,000						30,000,000
Capital Expenditures Incurred but Not yet Paid											(17,000,000)		14,000,000
Regulatory Liabilities					172,000,000						172,000,000				222,000,000
Public Utilities, Requested Rate Increase (Decrease), Amount											12,000,000
Estimated number of smart meters to be installed																		2,000,000
Total smart grid and smart meter investment grant amount																		$ 480,000,000
Reimbursements received from the DOE																		$ 200,000,000
Regulatory assets					508,000,000						508,000,000				514,000,000
Customer Refund					30,000,000						$ 30,000,000
Rate Of Return On Common Equity In Federal Energy Regulatory Committee Complaint											10.50%
Regulatory Liability, Current					54,000,000						$ 54,000,000				38,000,000
Other Commitment					263,000,000						263,000,000
Proposed Capital Expenditure											13,000,000
Baltimore Gas and Electric Company [Member] | Gas Distribution [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount		$ 48,000,000									78,000,000
Approved ROE		9.65%
Baltimore Gas and Electric Company [Member] | Electric Distribution [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount											116,000,000
Public Utilities, Approved Rate Increase (Decrease), Amount		$ 44,000,000
Approved ROE		9.75%
ICC Approved Rate Increase (Decrease), Amount		$ 44,000,000
Exelon Generation Co L L C [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Business Combination, Integration Related Costs					9,000,000				10,000,000		29,000,000		30,000,000
Unregulated Operating Revenue											101,000,000
Customer Refund Liability, Noncurrent					20,000,000						20,000,000
Capital Expenditures Incurred but Not yet Paid											289,000,000		48,000,000
Customer Refund					20,000,000						20,000,000
License Costs											27,000,000
Other Commitment					5,679,000,000						5,679,000,000						$ 91,000,000
Exelon Generation Co L L C [Member] | Minimum [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Purchase Obligation					3,000,000						3,000,000
Exelon Generation Co L L C [Member] | Maximum [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Purchase Obligation					7,000,000						7,000,000
PEPCO Holdings Inc [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Other Commitment					37,000,000						37,000,000
PEPCO Holdings Inc [Member] | Predecessor [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets															2,582,000,000
Regulatory Liabilities															213,000,000
Regulatory assets															2,277,000,000
Regulatory Liability, Current															66,000,000
PEPCO Holdings Inc [Member] | Successor [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					3,595,000,000						3,595,000,000
Regulatory Liabilities					268,000,000						268,000,000
Regulatory assets					2,945,000,000						2,945,000,000
Regulatory Liability, Current					101,000,000						101,000,000
Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					798,000,000						798,000,000				801,000,000
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount											(23,000,000)
Capital Expenditures Incurred but Not yet Paid											(15,000,000)		(1,000,000)
Regulatory Liabilities					44,000,000						44,000,000				44,000,000
Public Utilities, Requested Rate Increase (Decrease), Amount											2,000,000
Approved ROE							10.60%
Regulatory assets					676,000,000						$ 676,000,000				661,000,000
Public Utilities, Requested Return on Equity, Percentage							10.60%
Power Plant Output | MW			661,000,000
Rate Of Return On Common Equity In Federal Energy Regulatory Committee Complaint											10.50%
CapitalProjectFundedByEntity				$ 500,000,000
Capital ProjectFundedByBonds				375,000,000
CapitalProjectFundedByAgency				$ 125,000,000
Regulatory Liability, Current					20,000,000						$ 20,000,000				15,000,000
Other Commitment					15,000,000						15,000,000
Current Year Revenue Adjustment											(15,000,000)
Requested ROE							10.60%
Potomac Electric Power Company [Member] | Electric Distribution [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount					82,000,000		$ 103,000,000
Public Utilities, Requested Rate Increase (Decrease), Amount							127,000,000			$ 86,000,000
Potomac Electric Power Company [Member] | Minimum [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Power Plant Output | MW			650,000,000
Proposed Capital Expenditure							16,000,000
Potomac Electric Power Company [Member] | Maximum [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Power Plant Output | MW			700,000,000
Projected Capital Expenditures							32,000,000
Delmarva Power and Light Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					359,000,000						359,000,000				371,000,000
Business Combination, Integration Related Costs					2,000,000				0		18,000,000		2,000,000
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount											(14,000,000)
Capital Expenditures Incurred but Not yet Paid											10,000,000		2,000,000
Regulatory Liabilities					$ 146,000,000						146,000,000				160,000,000
Public Utilities, Requested Rate Increase (Decrease), Amount											8,000,000
Requested Debt and Equity Return on Distribution					10.60%
Public Utilities, Interim Rate Increase (Decrease), Amount							$ 2,500,000
Regulatory assets					$ 297,000,000						$ 297,000,000				299,000,000
Public Utilities, Requested Return on Equity, Percentage							10.60%
Rate Of Return On Common Equity In Federal Energy Regulatory Committee Complaint											10.50%
Regulatory Liability, Current					46,000,000						$ 46,000,000				49,000,000
Other Commitment					11,000,000						11,000,000
Current Year Revenue Adjustment											(12,000,000)
Requested ROE							10.60%
Delmarva Power and Light Company [Member] | Gas Distribution [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount							$ 21,500,000
Delmarva Power and Light Company [Member] | Electric Distribution [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount							57,000,000
Public Utilities, Requested Rate Increase (Decrease), Amount					66,000,000		62,800,000
Delmarva Power and Light Company [Member] | Minimum [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Projected Capital Expenditures					5,000,000
Delmarva Power and Light Company [Member] | Maximum [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Projected Capital Expenditures					9,000,000
Atlantic City Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					501,000,000						501,000,000				512,000,000
Business Combination, Integration Related Costs					2,000,000				$ 0		17,000,000		1,000,000
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount											(6,000,000)
Capital Expenditures Incurred but Not yet Paid											(2,000,000)		0
Regulatory Liabilities					36,000,000						36,000,000				25,000,000
Public Utilities, Requested Rate Increase (Decrease), Amount											8,000,000
Public Utilities, Interim Rate Increase (Decrease), Amount							$ 19,000,000	$ 9,000,000
Regulatory assets					412,000,000						$ 412,000,000				414,000,000
Rate Of Return On Common Equity In Federal Energy Regulatory Committee Complaint											10.50%
Regulatory Liability, Current					35,000,000						$ 35,000,000				18,000,000
Other Commitment					9,000,000						9,000,000
Current Year Revenue Adjustment											0
Atlantic City Electric Company [Member] | Electric Distribution [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount					45,000,000
ICC Approved Rate Increase (Decrease), Amount					45,000,000
Under Recovered Energy And Transmission Costs [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					74,000,000						74,000,000				84,000,000
Under Recovered Energy And Transmission Costs [Member] | Commonwealth Edison Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets	[1]				31,000,000						31,000,000				43,000,000
Business Combination, Integration Related Costs													7,000,000
Under Recovered Energy And Transmission Costs [Member] | PECO Energy Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					0						0				1,000,000	[2]
Under Recovered Energy And Transmission Costs [Member] | Baltimore Gas and Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets	[3]				25,000,000						25,000,000				40,000,000
Under Recovered Energy And Transmission Costs [Member] | PEPCO Holdings Inc [Member] | Predecessor [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets															33,000,000
Under Recovered Energy And Transmission Costs [Member] | PEPCO Holdings Inc [Member] | Successor [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					18,000,000						18,000,000
Under Recovered Energy And Transmission Costs [Member] | Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					1,000,000						1,000,000				9,000,000	[4]
Under Recovered Energy And Transmission Costs [Member] | Delmarva Power and Light Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets	[5]				8,000,000						8,000,000				11,000,000
Under Recovered Energy And Transmission Costs [Member] | Atlantic City Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets	[6]				9,000,000						9,000,000				13,000,000
Merger Integration Costs [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					23,000,000						23,000,000				6,000,000
Merger Integration Costs [Member] | Commonwealth Edison Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets															0
Merger Integration Costs [Member] | PECO Energy Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					0						0				0
Merger Integration Costs [Member] | Baltimore Gas and Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets	[7]				10,000,000						10,000,000				6,000,000
Merger Integration Costs [Member] | PEPCO Holdings Inc [Member] | Predecessor [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets															0
Merger Integration Costs [Member] | PEPCO Holdings Inc [Member] | Successor [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					13,000,000						13,000,000
Merger Integration Costs [Member] | Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					10,000,000	[8]					10,000,000	[8]			0
Merger Integration Costs [Member] | Delmarva Power and Light Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					3,000,000	[9]					3,000,000	[9]			0
Merger Integration Costs [Member] | Atlantic City Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					0						0				0
Under Recovered Distribution Service Costs [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					232,000,000						232,000,000				189,000,000
Under Recovered Distribution Service Costs [Member] | Commonwealth Edison Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets	[10]				232,000,000						232,000,000				189,000,000
Business Combination, Integration Related Costs											11,000,000		$ 11,000,000
Under Recovered Distribution Service Costs [Member] | PECO Energy Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					0						0				0
Under Recovered Distribution Service Costs [Member] | Baltimore Gas and Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					0						0				0
Under Recovered Distribution Service Costs [Member] | PEPCO Holdings Inc [Member] | Predecessor [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets															0
Under Recovered Distribution Service Costs [Member] | PEPCO Holdings Inc [Member] | Successor [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					0						0
Under Recovered Distribution Service Costs [Member] | Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					0						0				0
Under Recovered Distribution Service Costs [Member] | Delmarva Power and Light Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					0						0				0
Under Recovered Distribution Service Costs [Member] | Atlantic City Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					0						0				0
AMI Expenses [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					704,000,000						704,000,000				399,000,000
AMI Expenses [Member] | Commonwealth Edison Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					160,000,000						160,000,000				140,000,000
AMI Expenses [Member] | PECO Energy Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					53,000,000						53,000,000				63,000,000
AMI Expenses [Member] | Baltimore Gas and Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					235,000,000						235,000,000				196,000,000	[11]
Regulatory assets					235,000,000						235,000,000				196,000,000
Amount of Impairment to Carrying Amount of Regulatory Assets					52,000,000						52,000,000
AMI Expenses [Member] | Baltimore Gas and Electric Company [Member] | Gas Distribution [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount											37,000,000
AMI Expenses [Member] | Baltimore Gas and Electric Company [Member] | Electric Distribution [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount											104,000,000
AMI Expenses [Member] | PEPCO Holdings Inc [Member] | Predecessor [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets															267,000,000
AMI Expenses [Member] | PEPCO Holdings Inc [Member] | Successor [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					256,000,000						256,000,000
AMI Expenses [Member] | Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					171,000,000	[11]					171,000,000	[11]			180,000,000
AMI Expenses [Member] | Delmarva Power and Light Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					85,000,000	[11]					85,000,000	[11]			87,000,000
AMI Expenses [Member] | Atlantic City Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					0						0				0
Energy Efficiency And Demand Response Programs [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					642,000,000						642,000,000				279,000,000
Energy Efficiency And Demand Response Programs [Member] | Commonwealth Edison Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					0						0				0
Energy Efficiency And Demand Response Programs [Member] | PECO Energy Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					1,000,000						1,000,000				1,000,000
Energy Efficiency And Demand Response Programs [Member] | Baltimore Gas and Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					289,000,000						289,000,000				278,000,000
Energy Efficiency And Demand Response Programs [Member] | PEPCO Holdings Inc [Member] | Predecessor [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets															401,000,000
Energy Efficiency And Demand Response Programs [Member] | PEPCO Holdings Inc [Member] | Successor [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					352,000,000						352,000,000
Energy Efficiency And Demand Response Programs [Member] | Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					254,000,000						254,000,000				289,000,000
Energy Efficiency And Demand Response Programs [Member] | Delmarva Power and Light Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					98,000,000						98,000,000				111,000,000
Energy Efficiency And Demand Response Programs [Member] | Atlantic City Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					0						0				$ 1,000,000
Legacy AMI [Member] | Baltimore Gas and Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					55,000,000						55,000,000
Legacy AMI [Member] | Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					75,000,000						75,000,000
Legacy AMI [Member] | Delmarva Power and Light Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets					$ 14,000,000						$ 14,000,000
[1]	As of September 30, 2016, ComEd’s regulatory asset of $31 million included $24 million associated with transmission costs recoverable through its FERC approved formula rate and $7 million of Constellation merger and integration costs to be recovered upon FERC approval. As of September 30, 2016, ComEd’s regulatory liability of $72 million included $43 million related to over-recovered energy costs and $29 million associated with revenues received for renewable energy requirements. As of December 31, 2015, ComEd’s regulatory asset of $43 million included $5 million related to under-recovered energy costs, $31 million associated with transmission costs recoverable through its FERC approved formula rate, and $7 million of Constellation merger and integration costs to be recovered upon FERC approval. As of December 31, 2015, ComEd’s regulatory liability of $53 million included $29 million related to over-recovered energy costs and $24 million associated with revenues received for renewable energy requirements.
[2]	As of September 30, 2016, PECO's regulatory liability of $59 million included $30 million related to over-recovered costs under the DSP program, $13 million related to the over-recovered natural gas costs under the PGC, $10 million related to over-recovered non-bypassable transmission service charges and $6 million related to over-recovered electric transmission costs. As of December 31, 2015, PECO's regulatory asset of $1 million related to under-recovered non-bypassable transmission service charges. As of December 31, 2015, PECO's regulatory liability of $60 million included $35 million related to over-recovered costs under the DSP program, $22 million related to the over-recovered natural gas costs under the PGC and $3 million related to the over-recovered electric transmission costs.
[3]	As of September 30, 2016, BGE's regulatory asset of $25 million included $3 million of costs associated with transmission costs recoverable through its FERC approved formula rate, $19 million related to under-recovered electric energy costs, $3 million of abandonment costs to be recovered upon FERC approval, and $1 million related to under-recovered natural gas costs. As of December 31, 2015, BGE’s regulatory asset of $40 million included $12 million of costs associated with transmission costs recoverable through its FERC approved formula rate and $28 million related to under-recovered electric energy costs. As of December 31, 2015, BGE’s regulatory liability of $18 million related to $14 million of over-recovered transmission costs and $5 million of over-recovered natural gas costs, offset by $1 million of abandonment costs to be recovered upon FERC approval.
[4]	As of September 30, 2016, Pepco's regulatory liability of $17 million included $9 million of over-recovered transmission costs and $8 million of over-recovered electric energy costs. As of December 31, 2015, Pepco's regulatory asset of $9 million included $5 million of transmission costs recoverable through its FERC approved formula rate and $4 million of recoverable abandonment costs. As of December 31, 2015, Pepco's regulatory liability of $16 million included $14 million of over-recovered transmission costs and $2 million of over-recovered electric energy costs.
[5]	As of September 30, 2016, DPL's regulatory asset of $8 million included $1 million of transmission costs recoverable through its FERC approved formula rate and $7 million of under-recovered electric energy costs. As of September 30, 2016, DPL's regulatory liability of $11 million included $6 million of over-recovered electric energy costs and $5 million of over-recovered transmission costs. As of December 31, 2015, DPL's regulatory asset of $11 million included $7 million of transmission costs recoverable through its FERC approved formula rate, $3 million of recoverable abandonment costs, and $1 million of under-recovered electric energy costs. As of December 31, 2015, DPL's regulatory liability of $19 million included $4 million related to the over-recovered natural gas costs under the GCR mechanism, $4 million of over-recovered electric energy costs, and $11 million of over-recovered transmission costs.
[6]	As of September 30, 2016, ACE's regulatory asset of $9 million included $4 million of transmission costs recoverable through its FERC approved formula rate and $5 million of under-recovered electric energy costs. As of September 30, 2016, ACE's regulatory liability of $12 million included $7 million of over-recovered transmission costs and $5 million of over-recovered electric energy costs. As of December 31, 2015, ACE's regulatory asset of $13 million included $2 million of transmission costs recoverable through its FERC approved formula rate and $11 million of under-recovered electric energy costs. As of December 31, 2015, ACE's regulatory liability of $8 million related to over-recovered transmission costs.
[7]	As of September 30, 2016, BGE's regulatory asset of $10 million included $6 million of previously incurred PHI acquisition costs as authorized by the June 2016 rate case order.
[8]	epresents previously incurred PHI acquisition costs expected to be recovered in distribution rates
[9]	.
[10]	As of September 30, 2016, ComEd’s regulatory asset of $232 million was comprised of $178 million for the 2014 - 2016 annual reconciliations and $54 million related to significant one-time events including $24 million of deferred storm costs, $11 million of Constellation and PHI merger and integration related costs and $19 million of smart meter related costs. As of December 31, 2015, ComEd’s regulatory asset of $189 million was comprised of $142 million for the 2014 and 2015 annual reconciliations and $47 million related to significant one-time events, including $36 million of deferred storm costs and $11 million of Constellation merger and integration related costs. See Note 4— Merger, Acquisitions, and Dispositions of the Exelon 2015 Form 10-K for further information.
[11]	$134 million for Pepco and $40 million for DPL, of which $75 million for Pepco and $14 million for DPL relates to retired legacy meters which are not earning a return

Regulatory Matters Regulatory M

Regulatory Matters Regulatory Matters - Schedule of Regulatory Assets (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2016		Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015	Dec. 31, 2015
Regulatory Assets [Line Items]
Current		$ 1,410			$ 1,410			$ 759
Noncurrent		10,022			10,022			6,065
Regulatory Assets		11,432			11,432			6,824
Regulatory Liabilities		4,985			4,985			4,570
Business Combination, Integration Related Costs		20		$ 22	123		$ 84
Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets		4,096	[1]		4,096	[1]		3,156
Deferred Income Tax Charge [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1,973			1,973			1,616
AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets		704			704			399
Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		232			232			189
Loss on Reacquired Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		126			126			47
Fair Value Of Long Term Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		828			828			162	[2]
Fair Value Of Supply Contract [Member]
Regulatory Assets [Line Items]
Current		1,206			1,206
Employee Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets		6			6			9
Asset Retirement Obligation Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		108			108			108
Environmental Restoration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		295			295			286
Under Recovered Uncollectible Accounts Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets		58			58			52
Renewable Energy And Associated REC [Member]
Regulatory Assets [Line Items]
Regulatory Assets		246			246			247
Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		74			74			84
Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		39			39			2
Electric Generation Related Regulatory Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets		13			13			20
Rate Stabilization Deferral [Member]
Regulatory Assets [Line Items]
Regulatory Assets		25			25			87
Energy Efficiency And Demand Response Programs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		642			642			279
Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		23			23			6
ConservativeVoltageReductionProgram [Member]
Regulatory Assets [Line Items]
Regulatory Assets								3
Regulatory Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets		45			45			29
Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Regulatory Assets		9			9			30
Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		9			9			0
Workers Compensation and Long-Term Disability [Member]
Regulatory Assets [Line Items]
Regulatory Assets		30			30			0
Recoverable Vacation Pay [Member]
Regulatory Assets [Line Items]
Regulatory Assets		37			37			6
Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		153			153			0
CAP Arrearage [Member]
Regulatory Assets [Line Items]
Regulatory Assets		7			7			7
AssetRemovalCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets		448			448
Under funded Benefit Post Retirement Obligation [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1,087			1,087
Commonwealth Edison Co [Member]
Regulatory Assets [Line Items]
Current		205			205			218
Noncurrent		987			987			895
Regulatory Assets		1,192			1,192			1,113
Regulatory Liabilities		3,781			3,781			3,614
Business Combination, Integration Related Costs		0		3	(6)		9
Commonwealth Edison Co [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets		19			19			15
Commonwealth Edison Co [Member] | Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Commonwealth Edison Co [Member] | Deferred Income Tax Charge [Member]
Regulatory Assets [Line Items]
Regulatory Assets		73	[3]		73	[3]		64
Commonwealth Edison Co [Member] | Recoverable Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		54			54			47
Commonwealth Edison Co [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets		160			160			140
Commonwealth Edison Co [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[4]	232			232			189
Business Combination, Integration Related Costs					11		11
Commonwealth Edison Co [Member] | Loss on Reacquired Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		43			43			46
Commonwealth Edison Co [Member] | Fair Value Of Long Term Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Commonwealth Edison Co [Member] | Employee Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Commonwealth Edison Co [Member] | Asset Retirement Obligation Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		74			74			67
Commonwealth Edison Co [Member] | Environmental Restoration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		267			267			255
Commonwealth Edison Co [Member] | Under Recovered Uncollectible Accounts Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets		58			58			52
Commonwealth Edison Co [Member] | Renewable Energy And Associated REC [Member]
Regulatory Assets [Line Items]
Regulatory Assets		244			244			247
Commonwealth Edison Co [Member] | Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[5]	31			31			43
Business Combination, Integration Related Costs							7
Commonwealth Edison Co [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		24			24			36
Commonwealth Edison Co [Member] | Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Commonwealth Edison Co [Member] | Electric Generation Related Regulatory Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Commonwealth Edison Co [Member] | Rate Stabilization Deferral [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Commonwealth Edison Co [Member] | Energy Efficiency And Demand Response Programs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Commonwealth Edison Co [Member] | Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
Commonwealth Edison Co [Member] | ConservativeVoltageReductionProgram [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
Commonwealth Edison Co [Member] | Regulatory Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets		10			10			10
Business Combination, Integration Related Costs					8
Commonwealth Edison Co [Member] | Advanced Metering Infrastructure Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		19			19
Commonwealth Edison Co [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
Commonwealth Edison Co [Member] | Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Commonwealth Edison Co [Member] | Workers Compensation and Long-Term Disability [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Commonwealth Edison Co [Member] | Recoverable Vacation Pay [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Commonwealth Edison Co [Member] | Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Commonwealth Edison Co [Member] | Annual Reconciliations [Member]
Regulatory Assets [Line Items]
Regulatory Assets		178			178			142
Commonwealth Edison Co [Member] | Under-Recovered Electric Supply Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets								5
Commonwealth Edison Co [Member] | ElectricTransmissionCostsUnderRecovery [Member]
Regulatory Assets [Line Items]
Regulatory Assets		24			24			31
PECO Energy Co [Member]
Regulatory Assets [Line Items]
Current		37			37			34
Noncurrent		1,651			1,651			1,583
Regulatory Assets		1,688			1,688			1,617
Regulatory Liabilities		679			679			639
Business Combination, Integration Related Costs		1		1	3		4
PECO Energy Co [Member] | Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
PECO Energy Co [Member] | Deferred Income Tax Charge [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1,555			1,555			1,473
PECO Energy Co [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets		53			53			63
PECO Energy Co [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
PECO Energy Co [Member] | Loss on Reacquired Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1			1			1
PECO Energy Co [Member] | Fair Value Of Long Term Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
PECO Energy Co [Member] | Fair Value Of Supply Contract [Member]
Regulatory Assets [Line Items]
Current		0			0
PECO Energy Co [Member] | Employee Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
PECO Energy Co [Member] | Asset Retirement Obligation Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		22			22			22
PECO Energy Co [Member] | Environmental Restoration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		27			27			30
PECO Energy Co [Member] | Under Recovered Uncollectible Accounts Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
PECO Energy Co [Member] | Renewable Energy And Associated REC [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
PECO Energy Co [Member] | Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			1	[6]
PECO Energy Co [Member] | Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
PECO Energy Co [Member] | Electric Generation Related Regulatory Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0
PECO Energy Co [Member] | Rate Stabilization Deferral [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
PECO Energy Co [Member] | Energy Efficiency And Demand Response Programs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1			1			1
PECO Energy Co [Member] | Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
PECO Energy Co [Member] | ConservativeVoltageReductionProgram [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PECO Energy Co [Member] | Regulatory Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets		9			9			13
PECO Energy Co [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PECO Energy Co [Member] | Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
PECO Energy Co [Member] | Workers Compensation and Long-Term Disability [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
PECO Energy Co [Member] | Recoverable Vacation Pay [Member]
Regulatory Assets [Line Items]
Regulatory Assets		13			13			6
PECO Energy Co [Member] | Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
PECO Energy Co [Member] | CAP Arrearage [Member]
Regulatory Assets [Line Items]
Regulatory Assets		7			7			7
Baltimore Gas and Electric Company [Member]
Regulatory Assets [Line Items]
Current		214			214			267
Noncurrent		508			508			514
Regulatory Assets		722			722			781
Regulatory Liabilities		172			172			222
Business Combination, Integration Related Costs		1		2	(3)		4
Baltimore Gas and Electric Company [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets		32			32			16
Baltimore Gas and Electric Company [Member] | TransmissionCost [Member]
Regulatory Assets [Line Items]
Regulatory Assets		3			3			12
Baltimore Gas and Electric Company [Member] | UnderRecoveredElectricEnergyCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets		19			19			28
Baltimore Gas and Electric Company [Member] | Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Baltimore Gas and Electric Company [Member] | Deferred Income Tax Charge [Member]
Regulatory Assets [Line Items]
Regulatory Assets		94	[3]		94	[3]		79
Baltimore Gas and Electric Company [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Noncurrent		235			235			196
Regulatory Assets		235			235			196	[7]
Baltimore Gas and Electric Company [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Baltimore Gas and Electric Company [Member] | Loss on Reacquired Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		7			7			8
Baltimore Gas and Electric Company [Member] | Fair Value Of Long Term Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Baltimore Gas and Electric Company [Member] | Employee Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets		6			6			9
Baltimore Gas and Electric Company [Member] | Asset Retirement Obligation Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		11			11			19
Baltimore Gas and Electric Company [Member] | Environmental Restoration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1			1			1
Baltimore Gas and Electric Company [Member] | Under Recovered Uncollectible Accounts Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Baltimore Gas and Electric Company [Member] | Renewable Energy And Associated REC [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Baltimore Gas and Electric Company [Member] | Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[8]	25			25			40
Baltimore Gas and Electric Company [Member] | Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1			1			2
Baltimore Gas and Electric Company [Member] | Electric Generation Related Regulatory Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets		13			13			20
Baltimore Gas and Electric Company [Member] | Rate Stabilization Deferral [Member]
Regulatory Assets [Line Items]
Regulatory Assets		25			25			87
Baltimore Gas and Electric Company [Member] | Energy Efficiency And Demand Response Programs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		289			289			278
Baltimore Gas and Electric Company [Member] | Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[9]	10			10			6
Baltimore Gas and Electric Company [Member] | ConservativeVoltageReductionProgram [Member]
Regulatory Assets [Line Items]
Regulatory Assets								3
Baltimore Gas and Electric Company [Member] | Regulatory Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets		5			5			3
Business Combination, Integration Related Costs					6
Baltimore Gas and Electric Company [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[10]	0			0			30
Baltimore Gas and Electric Company [Member] | Under-Recovered Electric Revenue Decoupling [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			30
Baltimore Gas and Electric Company [Member] | Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Baltimore Gas and Electric Company [Member] | Workers Compensation and Long-Term Disability [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Baltimore Gas and Electric Company [Member] | Recoverable Vacation Pay [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Baltimore Gas and Electric Company [Member] | Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Baltimore Gas and Electric Company [Member] | Legacy AMI [Member]
Regulatory Assets [Line Items]
Regulatory Assets		55			55
Baltimore Gas and Electric Company [Member] | Recoverable Smart Meter Related Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		32			32
PEPCO Holdings Inc [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Current								305
Noncurrent								2,277
Regulatory Assets								2,582
Regulatory Liabilities								213
PEPCO Holdings Inc [Member] | Successor [Member]
Regulatory Assets [Line Items]
Current		650			650
Noncurrent		2,945			2,945
Regulatory Assets		3,595			3,595
Regulatory Liabilities		268			268
PEPCO Holdings Inc [Member] | Other Postretirement Benefits [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								910
PEPCO Holdings Inc [Member] | Other Postretirement Benefits [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[1]	0			0
PEPCO Holdings Inc [Member] | Deferred Income Tax Charge [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								214
PEPCO Holdings Inc [Member] | Deferred Income Tax Charge [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		251			251
PEPCO Holdings Inc [Member] | AMI Expenses [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								267
PEPCO Holdings Inc [Member] | AMI Expenses [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		256			256
PEPCO Holdings Inc [Member] | Under Recovered Distribution Service Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Under Recovered Distribution Service Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0
PEPCO Holdings Inc [Member] | Loss on Reacquired Debt [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								36
PEPCO Holdings Inc [Member] | Loss on Reacquired Debt [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[11]	82			82
PEPCO Holdings Inc [Member] | Fair Value Of Long Term Debt [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Fair Value Of Long Term Debt [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[2]	684			684
PEPCO Holdings Inc [Member] | Fair Value Of Supply Contract [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[12]	1,206			1,206
PEPCO Holdings Inc [Member] | Employee Severance [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Employee Severance [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0
PEPCO Holdings Inc [Member] | Asset Retirement Obligation Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								1
PEPCO Holdings Inc [Member] | Asset Retirement Obligation Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1			1
PEPCO Holdings Inc [Member] | Environmental Restoration Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Environmental Restoration Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0
PEPCO Holdings Inc [Member] | Under Recovered Uncollectible Accounts Expense [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Under Recovered Uncollectible Accounts Expense [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0
PEPCO Holdings Inc [Member] | Renewable Energy And Associated REC [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								6
PEPCO Holdings Inc [Member] | Renewable Energy And Associated REC [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		2			2
PEPCO Holdings Inc [Member] | Under Recovered Energy And Transmission Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								33
PEPCO Holdings Inc [Member] | Under Recovered Energy And Transmission Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		18			18
PEPCO Holdings Inc [Member] | Deferred Storm Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								43
PEPCO Holdings Inc [Member] | Deferred Storm Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		38			38
PEPCO Holdings Inc [Member] | Electric Generation Related Regulatory Asset [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Electric Generation Related Regulatory Asset [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0
PEPCO Holdings Inc [Member] | Rate Stabilization Deferral [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Rate Stabilization Deferral [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0
PEPCO Holdings Inc [Member] | Energy Efficiency And Demand Response Programs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								401
PEPCO Holdings Inc [Member] | Energy Efficiency And Demand Response Programs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		352			352
PEPCO Holdings Inc [Member] | Merger Integration Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Merger Integration Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		13			13
PEPCO Holdings Inc [Member] | ConservativeVoltageReductionProgram [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Regulatory Assets [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								32
PEPCO Holdings Inc [Member] | Regulatory Assets [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		19			19
PEPCO Holdings Inc [Member] | Under Recovered Decoupling Revenue [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								14
PEPCO Holdings Inc [Member] | Under Recovered Decoupling Revenue [Member] | Successor [Member]
Regulatory Assets [Line Items]
Current		9			9
PEPCO Holdings Inc [Member] | Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		9			9
PEPCO Holdings Inc [Member] | Deferred Project Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
PEPCO Holdings Inc [Member] | Workers Compensation and Long-Term Disability [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								31
PEPCO Holdings Inc [Member] | Workers Compensation and Long-Term Disability [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		30			30
PEPCO Holdings Inc [Member] | Recoverable Vacation Pay [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								23
PEPCO Holdings Inc [Member] | Recoverable Vacation Pay [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		24			24
PEPCO Holdings Inc [Member] | Stranded Costs [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								202
PEPCO Holdings Inc [Member] | Stranded Costs [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		153			153
PEPCO Holdings Inc [Member] | AssetRemovalCosts [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Assets								369
PEPCO Holdings Inc [Member] | AssetRemovalCosts [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets		448			448
Potomac Electric Power Company [Member]
Regulatory Assets [Line Items]
Current		122			122			140
Noncurrent		676			676			661
Regulatory Assets		798			798			801
Regulatory Liabilities		44			44			44
Potomac Electric Power Company [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets		29			29			36
Potomac Electric Power Company [Member] | TransmissionCost [Member]
Regulatory Assets [Line Items]
Regulatory Assets								5
Potomac Electric Power Company [Member] | UnderRecoveredElectricEnergyCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1			1
Potomac Electric Power Company [Member] | Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0	[1]		0	[1]		0
Potomac Electric Power Company [Member] | Deferred Income Tax Charge [Member]
Regulatory Assets [Line Items]
Regulatory Assets		162	[3]		162	[3]		137
Potomac Electric Power Company [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets		171	[7]		171	[7]		180
Potomac Electric Power Company [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Potomac Electric Power Company [Member] | Loss on Reacquired Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		18			18			19
Potomac Electric Power Company [Member] | Fair Value Of Long Term Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Potomac Electric Power Company [Member] | Employee Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Potomac Electric Power Company [Member] | Asset Retirement Obligation Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1			1			1
Potomac Electric Power Company [Member] | Environmental Restoration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Potomac Electric Power Company [Member] | Under Recovered Uncollectible Accounts Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Potomac Electric Power Company [Member] | Renewable Energy And Associated REC [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Potomac Electric Power Company [Member] | Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1			1			9	[13]
Potomac Electric Power Company [Member] | Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		14			14			19
Potomac Electric Power Company [Member] | Electric Generation Related Regulatory Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Potomac Electric Power Company [Member] | Rate Stabilization Deferral [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Potomac Electric Power Company [Member] | Energy Efficiency And Demand Response Programs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		254			254			289
Potomac Electric Power Company [Member] | Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		10	[14]		10	[14]		0
Potomac Electric Power Company [Member] | ConservativeVoltageReductionProgram [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
Potomac Electric Power Company [Member] | Regulatory Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets		11			11			14
Business Combination, Integration Related Costs					10
Potomac Electric Power Company [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Regulatory Assets		7			7			10
Potomac Electric Power Company [Member] | Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Potomac Electric Power Company [Member] | Workers Compensation and Long-Term Disability [Member]
Regulatory Assets [Line Items]
Regulatory Assets		30			30			31
Potomac Electric Power Company [Member] | Recoverable Vacation Pay [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Potomac Electric Power Company [Member] | Abandonment costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets								4
Potomac Electric Power Company [Member] | Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Potomac Electric Power Company [Member] | AssetRemovalCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets		119			119			92
Potomac Electric Power Company [Member] | Legacy AMI [Member]
Regulatory Assets [Line Items]
Regulatory Assets		75			75
Potomac Electric Power Company [Member] | Recoverable Smart Meter Related Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		134			134
Potomac Electric Power Company [Member] | AMI Post Test Year [Member]
Regulatory Assets [Line Items]
Regulatory Assets		3			3
Delmarva Power and Light Company [Member]
Regulatory Assets [Line Items]
Current		62			62			72
Noncurrent		297			297			299
Regulatory Assets		359			359			371
Regulatory Liabilities		146			146			160
Business Combination, Integration Related Costs		2		0	18		2
Delmarva Power and Light Company [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets		20			20			18
Delmarva Power and Light Company [Member] | TransmissionCost [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1			1			7
Delmarva Power and Light Company [Member] | UnderRecoveredElectricEnergyCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets		7			7			1
Delmarva Power and Light Company [Member] | Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0	[1]		0	[1]		0
Delmarva Power and Light Company [Member] | Deferred Income Tax Charge [Member]
Regulatory Assets [Line Items]
Regulatory Assets		38	[3]		38	[3]		36
Delmarva Power and Light Company [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets		85	[7]		85	[7]		87
Delmarva Power and Light Company [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Delmarva Power and Light Company [Member] | Loss on Reacquired Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		9			9			10
Delmarva Power and Light Company [Member] | Fair Value Of Long Term Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Delmarva Power and Light Company [Member] | Employee Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Delmarva Power and Light Company [Member] | Asset Retirement Obligation Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Delmarva Power and Light Company [Member] | Environmental Restoration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Delmarva Power and Light Company [Member] | Under Recovered Uncollectible Accounts Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Delmarva Power and Light Company [Member] | Renewable Energy And Associated REC [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			1
Delmarva Power and Light Company [Member] | Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[15]	8			8			11
Delmarva Power and Light Company [Member] | Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		5			5			6
Delmarva Power and Light Company [Member] | Electric Generation Related Regulatory Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Delmarva Power and Light Company [Member] | Rate Stabilization Deferral [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Delmarva Power and Light Company [Member] | Energy Efficiency And Demand Response Programs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		98			98			111
Delmarva Power and Light Company [Member] | Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		3	[16]		3	[16]		0
Delmarva Power and Light Company [Member] | ConservativeVoltageReductionProgram [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
Delmarva Power and Light Company [Member] | Regulatory Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets		4			4			9
Business Combination, Integration Related Costs					3
Delmarva Power and Light Company [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Current		2			2
Regulatory Assets								4
Delmarva Power and Light Company [Member] | Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		9			9			13
Delmarva Power and Light Company [Member] | Workers Compensation and Long-Term Disability [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Delmarva Power and Light Company [Member] | Recoverable Vacation Pay [Member]
Regulatory Assets [Line Items]
Regulatory Assets		14			14			14
Delmarva Power and Light Company [Member] | Abandonment costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets								3
Delmarva Power and Light Company [Member] | Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Delmarva Power and Light Company [Member] | AssetRemovalCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets		84			84			69
Delmarva Power and Light Company [Member] | Legacy AMI [Member]
Regulatory Assets [Line Items]
Regulatory Assets		14			14
Delmarva Power and Light Company [Member] | Recoverable Smart Meter Related Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		40			40
Atlantic City Electric Company [Member]
Regulatory Assets [Line Items]
Current		89			89			98
Noncurrent		412			412			414
Regulatory Assets		501			501			512
Regulatory Liabilities		36			36			25
Business Combination, Integration Related Costs		2		$ 0	17		$ 1
Atlantic City Electric Company [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets		18			18			15
Atlantic City Electric Company [Member] | TransmissionCost [Member]
Regulatory Assets [Line Items]
Regulatory Assets		4			4			2
Atlantic City Electric Company [Member] | UnderRecoveredElectricEnergyCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets		5			5			11
Atlantic City Electric Company [Member] | Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0	[1]		0	[1]		0
Atlantic City Electric Company [Member] | Deferred Income Tax Charge [Member]
Regulatory Assets [Line Items]
Regulatory Assets		51	[3]		51	[3]		41
Atlantic City Electric Company [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Atlantic City Electric Company [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Atlantic City Electric Company [Member] | Loss on Reacquired Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		6			6			7
Atlantic City Electric Company [Member] | Fair Value Of Long Term Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Atlantic City Electric Company [Member] | Fair Value Of Supply Contract [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0
Atlantic City Electric Company [Member] | Employee Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Atlantic City Electric Company [Member] | Asset Retirement Obligation Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Atlantic City Electric Company [Member] | Environmental Restoration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Atlantic City Electric Company [Member] | Under Recovered Uncollectible Accounts Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Atlantic City Electric Company [Member] | Renewable Energy And Associated REC [Member]
Regulatory Assets [Line Items]
Regulatory Assets		2			2			5
Atlantic City Electric Company [Member] | Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[17]	9			9			13
Atlantic City Electric Company [Member] | Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		19			19			18
Atlantic City Electric Company [Member] | Electric Generation Related Regulatory Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0
Atlantic City Electric Company [Member] | Rate Stabilization Deferral [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Atlantic City Electric Company [Member] | Energy Efficiency And Demand Response Programs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			1
Atlantic City Electric Company [Member] | Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Atlantic City Electric Company [Member] | ConservativeVoltageReductionProgram [Member]
Regulatory Assets [Line Items]
Regulatory Assets								0
Atlantic City Electric Company [Member] | Regulatory Assets [Member]
Regulatory Assets [Line Items]
Regulatory Assets		5			5			8
Atlantic City Electric Company [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Atlantic City Electric Company [Member] | Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Atlantic City Electric Company [Member] | Workers Compensation and Long-Term Disability [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
Atlantic City Electric Company [Member] | Recoverable Vacation Pay [Member]
Regulatory Assets [Line Items]
Regulatory Assets		10			10			9
Atlantic City Electric Company [Member] | Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		153			153			202
Atlantic City Electric Company [Member] | AssetRemovalCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets		$ 246			$ 246			$ 208
[1]	As of September 30, 2016, the pension and other postretirement benefits regulatory asset at Exelon includes regulatory assets of $1,087 million established at the date of the PHI Merger related to unrecognized costs that are probable of regulatory recovery. The regulatory assets are amortized over periods from 3 to 15 years, depending on the underlying component. Pepco, DPL and ACE are currently recovering these costs through base rates. Pepco, DPL and ACE are not earning a return on the recovery of these costs in base rates.
[2]	ncludes the unamortized regulatory assets recorded for the difference between carrying value and fair value of long-term debt of BGE as of the Constellation merger date and at Exelon and PHI for the difference between carrying value and fair value of long-term debt of Pepco, DPL and ACE as of the PHI Merger date.
[3]	As of September 30, 2016, includes transmission-related regulatory assets that require FERC approval separate from the transmission formula rate of $19 million, $32 million, $29 million, $20 million and $18 million for ComEd, BGE, Pepco, DPL and ACE, respectively. As of December 31, 2015, includes transmission-related regulatory assets that require FERC approval separate from the transmission formula rate of $15 million, $16 million, $36 million, $18 million and $15 million for ComEd, BGE, Pepco, DPL and ACE, respectively.
[4]	As of September 30, 2016, ComEd’s regulatory asset of $232 million was comprised of $178 million for the 2014 - 2016 annual reconciliations and $54 million related to significant one-time events including $24 million of deferred storm costs, $11 million of Constellation and PHI merger and integration related costs and $19 million of smart meter related costs. As of December 31, 2015, ComEd’s regulatory asset of $189 million was comprised of $142 million for the 2014 and 2015 annual reconciliations and $47 million related to significant one-time events, including $36 million of deferred storm costs and $11 million of Constellation merger and integration related costs. See Note 4— Merger, Acquisitions, and Dispositions of the Exelon 2015 Form 10-K for further information.
[5]	As of September 30, 2016, ComEd’s regulatory asset of $31 million included $24 million associated with transmission costs recoverable through its FERC approved formula rate and $7 million of Constellation merger and integration costs to be recovered upon FERC approval. As of September 30, 2016, ComEd’s regulatory liability of $72 million included $43 million related to over-recovered energy costs and $29 million associated with revenues received for renewable energy requirements. As of December 31, 2015, ComEd’s regulatory asset of $43 million included $5 million related to under-recovered energy costs, $31 million associated with transmission costs recoverable through its FERC approved formula rate, and $7 million of Constellation merger and integration costs to be recovered upon FERC approval. As of December 31, 2015, ComEd’s regulatory liability of $53 million included $29 million related to over-recovered energy costs and $24 million associated with revenues received for renewable energy requirements.
[6]	As of September 30, 2016, PECO's regulatory liability of $59 million included $30 million related to over-recovered costs under the DSP program, $13 million related to the over-recovered natural gas costs under the PGC, $10 million related to over-recovered non-bypassable transmission service charges and $6 million related to over-recovered electric transmission costs. As of December 31, 2015, PECO's regulatory asset of $1 million related to under-recovered non-bypassable transmission service charges. As of December 31, 2015, PECO's regulatory liability of $60 million included $35 million related to over-recovered costs under the DSP program, $22 million related to the over-recovered natural gas costs under the PGC and $3 million related to the over-recovered electric transmission costs.
[7]	$134 million for Pepco and $40 million for DPL, of which $75 million for Pepco and $14 million for DPL relates to retired legacy meters which are not earning a return
[8]	As of September 30, 2016, BGE's regulatory asset of $25 million included $3 million of costs associated with transmission costs recoverable through its FERC approved formula rate, $19 million related to under-recovered electric energy costs, $3 million of abandonment costs to be recovered upon FERC approval, and $1 million related to under-recovered natural gas costs. As of December 31, 2015, BGE’s regulatory asset of $40 million included $12 million of costs associated with transmission costs recoverable through its FERC approved formula rate and $28 million related to under-recovered electric energy costs. As of December 31, 2015, BGE’s regulatory liability of $18 million related to $14 million of over-recovered transmission costs and $5 million of over-recovered natural gas costs, offset by $1 million of abandonment costs to be recovered upon FERC approval.
[9]	As of September 30, 2016, BGE's regulatory asset of $10 million included $6 million of previously incurred PHI acquisition costs as authorized by the June 2016 rate case order.
[10]	Represents the electric and natural gas distribution costs recoverable from customers under BGE’s decoupling mechanism. As of September 30, 2016, BGE had a regulatory liability of $5 million related to over-recovered natural gas revenue decoupling and $0 million related to over-recovered electric revenue decoupling. As of December 31, 2015, BGE had a regulatory asset of $30 million related to under-recovered electric revenue decoupling and a regulatory liability of $1 million related to over-recovered natural gas revenue decoupling.
[11]	Includes at Exelon and PHI the regulatory asset recorded at PHI for debt costs that are recoverable through the ratemaking process at Pepco, DPL, and ACE which were eliminated at Exelon and PHI as part of acquisition accounting.
[12]	Represents the regulatory asset recorded at Exelon and PHI offsetting the fair value adjustments related to Pepco's, DPL's and ACE's electricity and natural gas energy supply contracts recorded at PHI as of the PHI Merger date. Pepco, DPL and ACE are allowed full recovery of the costs of these contracts through their respective rate making processes.
[13]	As of September 30, 2016, Pepco's regulatory liability of $17 million included $9 million of over-recovered transmission costs and $8 million of over-recovered electric energy costs. As of December 31, 2015, Pepco's regulatory asset of $9 million included $5 million of transmission costs recoverable through its FERC approved formula rate and $4 million of recoverable abandonment costs. As of December 31, 2015, Pepco's regulatory liability of $16 million included $14 million of over-recovered transmission costs and $2 million of over-recovered electric energy costs.
[14]	epresents previously incurred PHI acquisition costs expected to be recovered in distribution rates
[15]	As of September 30, 2016, DPL's regulatory asset of $8 million included $1 million of transmission costs recoverable through its FERC approved formula rate and $7 million of under-recovered electric energy costs. As of September 30, 2016, DPL's regulatory liability of $11 million included $6 million of over-recovered electric energy costs and $5 million of over-recovered transmission costs. As of December 31, 2015, DPL's regulatory asset of $11 million included $7 million of transmission costs recoverable through its FERC approved formula rate, $3 million of recoverable abandonment costs, and $1 million of under-recovered electric energy costs. As of December 31, 2015, DPL's regulatory liability of $19 million included $4 million related to the over-recovered natural gas costs under the GCR mechanism, $4 million of over-recovered electric energy costs, and $11 million of over-recovered transmission costs.
[16]	.
[17]	As of September 30, 2016, ACE's regulatory asset of $9 million included $4 million of transmission costs recoverable through its FERC approved formula rate and $5 million of under-recovered electric energy costs. As of September 30, 2016, ACE's regulatory liability of $12 million included $7 million of over-recovered transmission costs and $5 million of over-recovered electric energy costs. As of December 31, 2015, ACE's regulatory asset of $13 million included $2 million of transmission costs recoverable through its FERC approved formula rate and $11 million of under-recovered electric energy costs. As of December 31, 2015, ACE's regulatory liability of $8 million related to over-recovered transmission costs.

Regulatory Matters Regulatory60

Regulatory Matters Regulatory Matters - Schedule of Regulatory Liabilities (Details) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		$ 548	$ 369
Noncurrent		4,437	4,201
Regulatory Liabilities		4,985	4,570
Regulatory Assets		11,432	6,824
Electric Transmission And Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		79	95
Other Postretirement Benefits [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		85	94
Nuclear Decommissioning [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		2,704	2,577
Removal Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		1,627	1,527
Deferred Lease Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		40
Energy Efficiency Demand Response Programs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		175	92
Dlc Program Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		8	9
Gas Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		21	28
Over Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		171	131
Over Recovered Decoupling Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		5	1
Regulatory Liabilities Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		70	16
Baltimore Gas and Electric Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		54	38
Noncurrent		118	184
Regulatory Liabilities		172	222
Regulatory Assets		722	781
Baltimore Gas and Electric Company [Member] | Over Recovered Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			14
Baltimore Gas and Electric Company [Member] | Electric Transmission And Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Baltimore Gas and Electric Company [Member] | Abandonment costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		3	1
Baltimore Gas and Electric Company [Member] | Over Recovered Decoupling Gas Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		5	1
Baltimore Gas and Electric Company [Member] | Other Postretirement Benefits [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Baltimore Gas and Electric Company [Member] | Nuclear Decommissioning [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Baltimore Gas and Electric Company [Member] | Removal Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		151	195
Baltimore Gas and Electric Company [Member] | Energy Efficiency Demand Response Programs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Baltimore Gas and Electric Company [Member] | Dlc Program Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Baltimore Gas and Electric Company [Member] | Gas Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Baltimore Gas and Electric Company [Member] | Over Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[1]	0	18
Baltimore Gas and Electric Company [Member] | Over Recovered Decoupling Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[2]	5	1
Baltimore Gas and Electric Company [Member] | Regulatory Liabilities Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		16	8
Baltimore Gas and Electric Company [Member] | Over-Recovered Natural Gas Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		1	5
PECO Energy Co [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		128	112
Noncurrent		551	527
Regulatory Liabilities		679	639
Regulatory Assets		1,688	1,617
PECO Energy Co [Member] | Over Recovered NonBypassable Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		10
PECO Energy Co [Member] | Over Recovered Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		6	3
PECO Energy Co [Member] | Electric Transmission And Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		79	95
PECO Energy Co [Member] | Other Postretirement Benefits [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
PECO Energy Co [Member] | Nuclear Decommissioning [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		466	405
PECO Energy Co [Member] | Removal Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
PECO Energy Co [Member] | Energy Efficiency Demand Response Programs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		40	40
PECO Energy Co [Member] | Dlc Program Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		8	9
PECO Energy Co [Member] | Gas Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		21	28
PECO Energy Co [Member] | Over Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[3]	59	60
PECO Energy Co [Member] | Over Recovered Decoupling Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
PECO Energy Co [Member] | Regulatory Liabilities Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		6	2
PECO Energy Co [Member] | Over-Recovered Natural Gas Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		13	22
PECO Energy Co [Member] | Default Service Provider Program [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		30	35
Commonwealth Edison Co [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		204	155
Noncurrent		3,577	3,459
Regulatory Liabilities		3,781	3,614
Regulatory Assets		1,192	1,113
Commonwealth Edison Co [Member] | Electric Transmission And Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Commonwealth Edison Co [Member] | Other Postretirement Benefits [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Commonwealth Edison Co [Member] | Nuclear Decommissioning [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		2,238	2,172
Commonwealth Edison Co [Member] | Removal Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		1,333	1,332
Commonwealth Edison Co [Member] | Energy Efficiency Demand Response Programs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		135	52
Commonwealth Edison Co [Member] | Dlc Program Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			0
Commonwealth Edison Co [Member] | Gas Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Commonwealth Edison Co [Member] | Over Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[4]	72	53
Commonwealth Edison Co [Member] | Over Recovered Decoupling Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Commonwealth Edison Co [Member] | Regulatory Liabilities Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		3	5
Commonwealth Edison Co [Member] | Renewable energy Requirements [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		29	24
Commonwealth Edison Co [Member] | Over Recovered Electric Supply Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		43	29
PEPCO Holdings Inc [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current			66
Noncurrent			147
Regulatory Liabilities			213
Regulatory Assets			2,582
PEPCO Holdings Inc [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		101
Noncurrent		167
Regulatory Liabilities		268
Regulatory Assets		3,595
PEPCO Holdings Inc [Member] | Electric Transmission And Distribution Tax Repairs [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			0
PEPCO Holdings Inc [Member] | Electric Transmission And Distribution Tax Repairs [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0
PEPCO Holdings Inc [Member] | Other Postretirement Benefits [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			0
PEPCO Holdings Inc [Member] | Other Postretirement Benefits [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0
PEPCO Holdings Inc [Member] | Nuclear Decommissioning [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			0
PEPCO Holdings Inc [Member] | Nuclear Decommissioning [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0
PEPCO Holdings Inc [Member] | Removal Costs [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			150
PEPCO Holdings Inc [Member] | Removal Costs [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		143
PEPCO Holdings Inc [Member] | Deferred Lease Revenue [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[5]	40
PEPCO Holdings Inc [Member] | Energy Efficiency Demand Response Programs [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			1
PEPCO Holdings Inc [Member] | Energy Efficiency Demand Response Programs [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0
PEPCO Holdings Inc [Member] | Dlc Program Cost [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			0
PEPCO Holdings Inc [Member] | Dlc Program Cost [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0
PEPCO Holdings Inc [Member] | Gas Distribution Tax Repairs [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			0
PEPCO Holdings Inc [Member] | Gas Distribution Tax Repairs [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0
PEPCO Holdings Inc [Member] | Over Recovered Energy And Transmission Costs [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			27
PEPCO Holdings Inc [Member] | Over Recovered Energy And Transmission Costs [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		40
PEPCO Holdings Inc [Member] | Over Recovered Decoupling Revenue [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			0
PEPCO Holdings Inc [Member] | Over Recovered Decoupling Revenue [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0
PEPCO Holdings Inc [Member] | Regulatory Liabilities Other [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			35
PEPCO Holdings Inc [Member] | Regulatory Liabilities Other [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		45
Potomac Electric Power Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		20	15
Noncurrent		24	29
Regulatory Liabilities		44	44
Regulatory Assets		798	801
Potomac Electric Power Company [Member] | Over Recovered Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		9	14
Potomac Electric Power Company [Member] | Electric Transmission And Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Potomac Electric Power Company [Member] | Other Postretirement Benefits [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Potomac Electric Power Company [Member] | Nuclear Decommissioning [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Potomac Electric Power Company [Member] | Removal Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		20	21
Potomac Electric Power Company [Member] | Energy Efficiency Demand Response Programs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Potomac Electric Power Company [Member] | Dlc Program Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Potomac Electric Power Company [Member] | Gas Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Potomac Electric Power Company [Member] | Over Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[6]	17	16
Potomac Electric Power Company [Member] | Over Recovered Decoupling Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Potomac Electric Power Company [Member] | Regulatory Liabilities Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		7	7
Potomac Electric Power Company [Member] | Over Recovered Electric Supply Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		8	2
Delmarva Power and Light Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		46	49
Noncurrent		100	111
Regulatory Liabilities		146	160
Regulatory Assets		359	371
Delmarva Power and Light Company [Member] | Over Recovered Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		5	11
Delmarva Power and Light Company [Member] | Electric Transmission And Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Delmarva Power and Light Company [Member] | Other Postretirement Benefits [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Delmarva Power and Light Company [Member] | Nuclear Decommissioning [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Delmarva Power and Light Company [Member] | Removal Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		123	129
Delmarva Power and Light Company [Member] | Energy Efficiency Demand Response Programs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Delmarva Power and Light Company [Member] | Dlc Program Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Delmarva Power and Light Company [Member] | Gas Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Delmarva Power and Light Company [Member] | Over Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[7]	11	19
Delmarva Power and Light Company [Member] | Over Recovered Decoupling Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Delmarva Power and Light Company [Member] | Regulatory Liabilities Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		12	12
Delmarva Power and Light Company [Member] | Over-Recovered Natural Gas Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			4
Delmarva Power and Light Company [Member] | Over Recovered Electric Supply Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		6	4
Atlantic City Electric Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		35	18
Noncurrent		1	7
Regulatory Liabilities		36	25
Regulatory Assets		501	512
Atlantic City Electric Company [Member] | Over Recovered Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		7
Atlantic City Electric Company [Member] | Electric Transmission And Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Atlantic City Electric Company [Member] | Other Postretirement Benefits [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Atlantic City Electric Company [Member] | Nuclear Decommissioning [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Atlantic City Electric Company [Member] | Removal Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Atlantic City Electric Company [Member] | Energy Efficiency Demand Response Programs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	1
Atlantic City Electric Company [Member] | Dlc Program Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Atlantic City Electric Company [Member] | Gas Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Atlantic City Electric Company [Member] | Over Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[8]	12	8
Atlantic City Electric Company [Member] | Over Recovered Decoupling Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		0	0
Atlantic City Electric Company [Member] | Regulatory Liabilities Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		24	16
Atlantic City Electric Company [Member] | Over Recovered Electric Supply Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		5
Under-Recovered Electric Revenue Decoupling [Member] | Baltimore Gas and Electric Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets		0	30
Under Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets		74	84
Under Recovered Energy And Transmission Costs [Member] | Baltimore Gas and Electric Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets	[1]	25	40
Under Recovered Energy And Transmission Costs [Member] | PECO Energy Co [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets		0	1	[3]
Under Recovered Energy And Transmission Costs [Member] | Commonwealth Edison Co [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets	[4]	31	43
Under Recovered Energy And Transmission Costs [Member] | PEPCO Holdings Inc [Member] | Predecessor [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets			33
Under Recovered Energy And Transmission Costs [Member] | PEPCO Holdings Inc [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets		18
Under Recovered Energy And Transmission Costs [Member] | Potomac Electric Power Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets		1	9	[6]
Under Recovered Energy And Transmission Costs [Member] | Delmarva Power and Light Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets	[7]	8	11
Under Recovered Energy And Transmission Costs [Member] | Atlantic City Electric Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets	[8]	$ 9	$ 13
[1]	As of September 30, 2016, BGE's regulatory asset of $25 million included $3 million of costs associated with transmission costs recoverable through its FERC approved formula rate, $19 million related to under-recovered electric energy costs, $3 million of abandonment costs to be recovered upon FERC approval, and $1 million related to under-recovered natural gas costs. As of December 31, 2015, BGE’s regulatory asset of $40 million included $12 million of costs associated with transmission costs recoverable through its FERC approved formula rate and $28 million related to under-recovered electric energy costs. As of December 31, 2015, BGE’s regulatory liability of $18 million related to $14 million of over-recovered transmission costs and $5 million of over-recovered natural gas costs, offset by $1 million of abandonment costs to be recovered upon FERC approval.
[2]	Represents the electric and natural gas distribution costs recoverable from customers under BGE’s decoupling mechanism. As of September 30, 2016, BGE had a regulatory liability of $5 million related to over-recovered natural gas revenue decoupling and $0 million related to over-recovered electric revenue decoupling. As of December 31, 2015, BGE had a regulatory asset of $30 million related to under-recovered electric revenue decoupling and a regulatory liability of $1 million related to over-recovered natural gas revenue decoupling.
[3]	As of September 30, 2016, PECO's regulatory liability of $59 million included $30 million related to over-recovered costs under the DSP program, $13 million related to the over-recovered natural gas costs under the PGC, $10 million related to over-recovered non-bypassable transmission service charges and $6 million related to over-recovered electric transmission costs. As of December 31, 2015, PECO's regulatory asset of $1 million related to under-recovered non-bypassable transmission service charges. As of December 31, 2015, PECO's regulatory liability of $60 million included $35 million related to over-recovered costs under the DSP program, $22 million related to the over-recovered natural gas costs under the PGC and $3 million related to the over-recovered electric transmission costs.
[4]	As of September 30, 2016, ComEd’s regulatory asset of $31 million included $24 million associated with transmission costs recoverable through its FERC approved formula rate and $7 million of Constellation merger and integration costs to be recovered upon FERC approval. As of September 30, 2016, ComEd’s regulatory liability of $72 million included $43 million related to over-recovered energy costs and $29 million associated with revenues received for renewable energy requirements. As of December 31, 2015, ComEd’s regulatory asset of $43 million included $5 million related to under-recovered energy costs, $31 million associated with transmission costs recoverable through its FERC approved formula rate, and $7 million of Constellation merger and integration costs to be recovered upon FERC approval. As of December 31, 2015, ComEd’s regulatory liability of $53 million included $29 million related to over-recovered energy costs and $24 million associated with revenues received for renewable energy requirements.
[5]	Represents the regulatory liability recorded at Exelon and PHI for deferred rent related to a lease that is recoverable through the ratemaking process at Pepco, DPL and ACE.
[6]	As of September 30, 2016, Pepco's regulatory liability of $17 million included $9 million of over-recovered transmission costs and $8 million of over-recovered electric energy costs. As of December 31, 2015, Pepco's regulatory asset of $9 million included $5 million of transmission costs recoverable through its FERC approved formula rate and $4 million of recoverable abandonment costs. As of December 31, 2015, Pepco's regulatory liability of $16 million included $14 million of over-recovered transmission costs and $2 million of over-recovered electric energy costs.
[7]	As of September 30, 2016, DPL's regulatory asset of $8 million included $1 million of transmission costs recoverable through its FERC approved formula rate and $7 million of under-recovered electric energy costs. As of September 30, 2016, DPL's regulatory liability of $11 million included $6 million of over-recovered electric energy costs and $5 million of over-recovered transmission costs. As of December 31, 2015, DPL's regulatory asset of $11 million included $7 million of transmission costs recoverable through its FERC approved formula rate, $3 million of recoverable abandonment costs, and $1 million of under-recovered electric energy costs. As of December 31, 2015, DPL's regulatory liability of $19 million included $4 million related to the over-recovered natural gas costs under the GCR mechanism, $4 million of over-recovered electric energy costs, and $11 million of over-recovered transmission costs.
[8]	As of September 30, 2016, ACE's regulatory asset of $9 million included $4 million of transmission costs recoverable through its FERC approved formula rate and $5 million of under-recovered electric energy costs. As of September 30, 2016, ACE's regulatory liability of $12 million included $7 million of over-recovered transmission costs and $5 million of over-recovered electric energy costs. As of December 31, 2015, ACE's regulatory asset of $13 million included $2 million of transmission costs recoverable through its FERC approved formula rate and $11 million of under-recovered electric energy costs. As of December 31, 2015, ACE's regulatory liability of $8 million related to over-recovered transmission costs.

Regulatory Matters Regulatory61

Regulatory Matters Regulatory Matters - Purchase of Receivables Programs (Details) - USD ($) $ in Millions		9 Months Ended		12 Months Ended
		Sep. 30, 2016		Dec. 31, 2015
Purchase Of Receivables [Line Items]
Payments to Acquire Other Receivables		$ 396		$ 229
Allowance for Doubtful Accounts Receivable		36	[1]	31
Payments to Acquire Other Receivables, Net		$ 360		198
Discount rate		1.00%
Commonwealth Edison Co [Member]
Purchase Of Receivables [Line Items]
Payments to Acquire Other Receivables		$ 123		103
Allowance for Doubtful Accounts Receivable		17	[1]	16
Payments to Acquire Other Receivables, Net		106		87
PECO Energy Co [Member]
Purchase Of Receivables [Line Items]
Payments to Acquire Other Receivables		90		67
Allowance for Doubtful Accounts Receivable	[2]	7		7
Payments to Acquire Other Receivables, Net		83		60
Baltimore Gas and Electric Company [Member]
Purchase Of Receivables [Line Items]
Payments to Acquire Other Receivables		66		59
Allowance for Doubtful Accounts Receivable	[1]	6		8
Payments to Acquire Other Receivables, Net		60		51	[3]
PEPCO Holdings Inc [Member] | Predecessor [Member]
Purchase Of Receivables [Line Items]
Payments to Acquire Other Receivables				100
Allowance for Doubtful Accounts Receivable	[1]			6
Payments to Acquire Other Receivables, Net				94
PEPCO Holdings Inc [Member] | Successor [Member]
Purchase Of Receivables [Line Items]
Payments to Acquire Other Receivables		117
Allowance for Doubtful Accounts Receivable	[1]	6
Payments to Acquire Other Receivables, Net		$ 111
Potomac Electric Power Company [Member] | Maryland Service Territory [Member] | Minimum [Member]
Purchase Of Receivables [Line Items]
Weighted Average Discount Rate, Percent		0.00%
Potomac Electric Power Company [Member] | Maryland Service Territory [Member] | Maximum [Member]
Purchase Of Receivables [Line Items]
Weighted Average Discount Rate, Percent		2.00%
Potomac Electric Power Company [Member] | District of Columbia Service Territory [Member] | Minimum [Member]
Purchase Of Receivables [Line Items]
Weighted Average Discount Rate, Percent		0.00%
Potomac Electric Power Company [Member] | District of Columbia Service Territory [Member] | Maximum [Member]
Purchase Of Receivables [Line Items]
Weighted Average Discount Rate, Percent		6.00%
Potomac Electric Power Company [Member] | Predecessor [Member]
Purchase Of Receivables [Line Items]
Payments to Acquire Other Receivables				70
Allowance for Doubtful Accounts Receivable	[4]			4
Payments to Acquire Other Receivables, Net				66
Potomac Electric Power Company [Member] | Successor [Member]
Purchase Of Receivables [Line Items]
Payments to Acquire Other Receivables		$ 79
Allowance for Doubtful Accounts Receivable	[4]	4
Payments to Acquire Other Receivables, Net		$ 75
Delmarva Power and Light Company [Member] | Maryland Service Territory [Member] | Minimum [Member]
Purchase Of Receivables [Line Items]
Weighted Average Discount Rate, Percent		0.00%
Delmarva Power and Light Company [Member] | Maryland Service Territory [Member] | Maximum [Member]
Purchase Of Receivables [Line Items]
Weighted Average Discount Rate, Percent		1.00%
Delmarva Power and Light Company [Member] | Predecessor [Member]
Purchase Of Receivables [Line Items]
Payments to Acquire Other Receivables				11
Allowance for Doubtful Accounts Receivable	[1]			0
Payments to Acquire Other Receivables, Net				11
Delmarva Power and Light Company [Member] | Successor [Member]
Purchase Of Receivables [Line Items]
Payments to Acquire Other Receivables		$ 12
Allowance for Doubtful Accounts Receivable	[1]	0
Payments to Acquire Other Receivables, Net		12
Atlantic City Electric Company [Member] | Predecessor [Member]
Purchase Of Receivables [Line Items]
Payments to Acquire Other Receivables				19
Allowance for Doubtful Accounts Receivable	[1]			2
Payments to Acquire Other Receivables, Net				$ 17
Atlantic City Electric Company [Member] | Successor [Member]
Purchase Of Receivables [Line Items]
Payments to Acquire Other Receivables		26
Allowance for Doubtful Accounts Receivable	[1]	2
Payments to Acquire Other Receivables, Net		$ 24
[1]	For ComEd, BGE, Pepco and DPL, reflects the incremental allowance for uncollectible accounts recorded, which is in addition to the purchase discount. For ComEd, the incremental uncollectible accounts expense is recovered through its Purchase of Receivables with Consolidated Billing tariff
[2]	PECO’s natural gas POR program became effective on January 1, 2012 and included a 1% discount on purchased receivables in order to recover the implementation costs of the program. The implementation costs were fully recovered and the 1% discount was reset to 0%, effective July 2015
[3]	As of September 30, 2016, BGE's regulatory asset of $25 million included $3 million of costs associated with transmission costs recoverable through its FERC approved formula rate, $19 million related to under-recovered electric energy costs, $3 million of abandonment costs to be recovered upon FERC approval, and $1 million related to under-recovered natural gas costs. As of December 31, 2015, BGE’s regulatory asset of $40 million included $12 million of costs associated with transmission costs recoverable through its FERC approved formula rate and $28 million related to under-recovered electric energy costs. As of December 31, 2015, BGE’s regulatory liability of $18 million related to $14 million of over-recovered transmission costs and $5 million of over-recovered natural gas costs, offset by $1 million of abandonment costs to be recovered upon FERC approval.
[4]	Pepco's electric POR program in Maryland included a discount on purchased receivables ranging from 0% to 2% depending on customer class, and Pepco's electric POR program in the District of Columbia included a discount on purchased receivables ranging from 0% to 6% depending on customer class. DPL's electric POR program in Maryland included a discount on purchased receivables ranging from 0% to 1% depending on customer class.

Regulatory Matters Annual Elect

Regulatory Matters Annual Electric Transmission Fillings (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Sep. 30, 2016	Sep. 30, 2015
Commonwealth Edison Co [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 90
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount			$ 94
Public Utilities, Approved Return on Equity, Percentage			11.50%
Public Utilities, Approved Equity Capital Structure, Percentage			8.47%	8.61%
Prior Year Revenue Adjustment			$ 4
Baltimore Gas and Electric Company [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			12
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount			$ 28
Public Utilities, Approved Return on Equity, Percentage			10.50%
Public Utilities, Approved Equity Capital Structure, Percentage			8.09%	8.46%
Prior Year Revenue Adjustment			$ 3
Proposed Capital Expenditure			13
Potomac Electric Power Company [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			2
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount			$ (23)
Public Utilities, Approved Return on Equity, Percentage		10.60%
Public Utilities, Approved Return on Equity, Percentage			10.50%
Public Utilities, Approved Equity Capital Structure, Percentage			7.88%	8.36%
Prior Year Revenue Adjustment	$ (10)
Current Year Revenue Adjustment			$ (15)
Delmarva Power and Light Company [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			8
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount			$ (14)
Public Utilities, Approved Return on Equity, Percentage			10.50%
Public Utilities, Requested Equity Capital Structure, Percentage	10.60%
Public Utilities, Approved Equity Capital Structure, Percentage			7.21%	7.80%
Prior Year Revenue Adjustment	$ (10)
Current Year Revenue Adjustment			$ (12)
Atlantic City Electric Company [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			8
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount			$ (6)
Public Utilities, Approved Return on Equity, Percentage			10.50%
Public Utilities, Approved Equity Capital Structure, Percentage			7.83%	8.51%
Prior Year Revenue Adjustment	$ (14)
Current Year Revenue Adjustment			$ 0

Impairment of Long-Lived Asse63

Impairment of Long-Lived Assets (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015	Mar. 31, 2016
Capital Leases, Net Investment in Direct Financing Leases [Abstract]
Estimated residual value of leased assets	$ 356	$ 356
Proceeds From Lease Termination		360	$ 0
Gain (Loss) on Contract Termination		4
Wind Assets [Member]
Capital Leases, Net Investment in Direct Financing Leases [Abstract]
Tangible Asset Impairment Charges		36
Disposal Group, Including Discontinued Operation, Assets, Current	24	24		$ 60
Constellation Energy Group LLC [Member]
Capital Leases, Net Investment in Direct Financing Leases [Abstract]
Tangible Asset Impairment Charges	$ 15	$ 119

Early Nuclear Plant Retiremen64

Early Nuclear Plant Retirements Early Nuclear Plant Retirements (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Inventory, Raw Materials and Supplies, Gross	$ 1,188	$ 1,104
Property, plant and equipment, net	71,214	$ 57,439
Ginna [Member]
Property, Plant and Equipment [Line Items]
Inventory, Raw Materials and Supplies, Gross	31
Nuclear Fuel, Net of Amortization	41
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	13
Asset Retirement Obligation	(667)
Property, plant and equipment, net	124
Three Mile Island [Member]
Property, Plant and Equipment [Line Items]
Inventory, Raw Materials and Supplies, Gross	39
Nuclear Fuel, Net of Amortization	93
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	38
Asset Retirement Obligation	(492)
Property, plant and equipment, net	956
Nine Mile Point [Member]
Property, Plant and Equipment [Line Items]
Inventory, Raw Materials and Supplies, Gross	70
Nuclear Fuel, Net of Amortization	214
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	53
Asset Retirement Obligation	(780)
Property, plant and equipment, net	$ 1,151

Early Nuclear Plant Retiremen65

Early Nuclear Plant Retirements Early Nuclear Plant Retirements table (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015
Property, Plant and Equipment [Line Items]
Nuclear Fuel Amortization	[1]	$ 862	$ 841
Asset Retirement Obligation, Accretion Expense	[2]	333	291
Depreciation	[3]	2,490	$ 1,648
Facility Closing [Member]
Property, Plant and Equipment [Line Items]
Other Expenses		443
Restructuring Reserve, Accrual Adjustment		$ 146
[1]	Included in Purchased power and fuel expense on the Registrants’ Consolidated Statements of Operations and Comprehensive Income
[2]	Included in Operating and maintenance expense on the Registrants’ Consolidated Statements of Operations and Comprehensive Income
[3]	(a)Included in Depreciation and amortization on the Registrants' Consolidated Statements of Operations and Comprehensive Income.

Early Nuclear Plant Retiremen66

Early Nuclear Plant Retirements Early Plant Retirement Pretax Expense (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Nuclear Fuel Amortization	[1]			$ 862	$ 841
Depreciation	[2]			2,490	1,648
Other, net		$ 120	$ (244)	377	$ (179)
Nuclear Plant [Member]
Nuclear Fuel Amortization				37
Depreciation				459
Accretion Expense, Including Asset Retirement Obligations				2
Other, net				(55)
Other Expenses				$ 443
[1]	Included in Purchased power and fuel expense on the Registrants’ Consolidated Statements of Operations and Comprehensive Income
[2]	(a)Included in Depreciation and amortization on the Registrants' Consolidated Statements of Operations and Comprehensive Income.

Fair Value of Financial Asset67

Fair Value of Financial Assets and Liabilities - Fair Value of Financial Liabilities Recorded at the Carrying Amount (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015	Oct. 01, 2015
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Spent Nuclear Fuel Obligation, Noncurrent	$ 1,023	$ 1,021
Due to Related Parties, Noncurrent	642	641
Preferred Stock, Value, Issued	0	193
Deferred Finance Costs, Net	204	180
Financing Trusts [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Deferred Finance Costs, Net	7
Reported Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	567	536
Long-term debt (including amounts due within one year)(a)	34,842	25,145
Spent Nuclear Fuel Obligation, Noncurrent	1,023	1,021
Due to Related Parties, Noncurrent	642	641
Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	567	536
Long-term debt (including amounts due within one year)(a)	37,626	25,924
Spent Nuclear Fuel Obligation, Noncurrent	856	818
Due to Related Parties, Noncurrent	692	673
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	0	3
Long-term debt (including amounts due within one year)(a)	1,075	931
Spent Nuclear Fuel Obligation, Noncurrent	0	0
Due to Related Parties, Noncurrent	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	567	533
Long-term debt (including amounts due within one year)(a)	34,272	23,644
Spent Nuclear Fuel Obligation, Noncurrent	856	818
Due to Related Parties, Noncurrent	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	0	0
Long-term debt (including amounts due within one year)(a)	2,279	1,349
Spent Nuclear Fuel Obligation, Noncurrent	0	0
Due to Related Parties, Noncurrent	692	673
Exelon Generation Co L L C [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Spent Nuclear Fuel Obligation, Noncurrent	1,023	1,021
Deferred Finance Costs, Net	68	70
Exelon Generation Co L L C [Member] | Reported Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	40	29
Long-term debt (including amounts due within one year)(a)	9,255	8,959
Spent Nuclear Fuel Obligation, Noncurrent	1,023	1,021
Exelon Generation Co L L C [Member] | Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	40	29
Long-term debt (including amounts due within one year)(a)	9,699	9,116
Spent Nuclear Fuel Obligation, Noncurrent	856	818
Exelon Generation Co L L C [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	0	0
Long-term debt (including amounts due within one year)(a)	0	0
Spent Nuclear Fuel Obligation, Noncurrent	0	0
Exelon Generation Co L L C [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	40	29
Long-term debt (including amounts due within one year)(a)	8,015	7,767
Spent Nuclear Fuel Obligation, Noncurrent	856	818
Exelon Generation Co L L C [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	0	0
Long-term debt (including amounts due within one year)(a)	1,684	1,349
Spent Nuclear Fuel Obligation, Noncurrent	0	0
Commonwealth Edison Co [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Due to Related Parties, Noncurrent	205	205
Deferred Finance Costs, Net	47	38
Commonwealth Edison Co [Member] | Financing Trusts [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Deferred Finance Costs, Net	1
Commonwealth Edison Co [Member] | Reported Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	10	294
Long-term debt (including amounts due within one year)(a)	7,031	6,509
Due to Related Parties, Noncurrent	205	205
Commonwealth Edison Co [Member] | Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	10	294
Long-term debt (including amounts due within one year)(a)	8,081	7,069
Due to Related Parties, Noncurrent	218	213
Commonwealth Edison Co [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	0	0
Long-term debt (including amounts due within one year)(a)	0	0
Due to Related Parties, Noncurrent	0	0
Commonwealth Edison Co [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	10	294
Long-term debt (including amounts due within one year)(a)	8,081	7,069
Due to Related Parties, Noncurrent	0	0
Commonwealth Edison Co [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	0	0
Long-term debt (including amounts due within one year)(a)	0	0
Due to Related Parties, Noncurrent	218	213
PECO Energy Co [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Due to Related Parties, Noncurrent	184	184
Deferred Finance Costs, Net	16	15
PECO Energy Co [Member] | Reported Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)(a)	2,879	2,580
Due to Related Parties, Noncurrent	184	184
PECO Energy Co [Member] | Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)(a)	3,266	2,786
Due to Related Parties, Noncurrent	207	195
PECO Energy Co [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)(a)	0	0
Due to Related Parties, Noncurrent	0	0
PECO Energy Co [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)(a)	3,266	2,786
Due to Related Parties, Noncurrent	0	0
PECO Energy Co [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt (including amounts due within one year)(a)	0	0
Due to Related Parties, Noncurrent	207	195
Baltimore Gas and Electric Company [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Due to Related Parties, Noncurrent	252	252
Preferred Stock, Value, Issued	0	190	$ 190
Deferred Finance Costs, Net	15	9
Baltimore Gas and Electric Company [Member] | Financing Trusts [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Deferred Finance Costs, Net	6
Baltimore Gas and Electric Company [Member] | Reported Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		213
Long-term debt (including amounts due within one year)(a)	2,662	1,858
Due to Related Parties, Noncurrent	252	252
Baltimore Gas and Electric Company [Member] | Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		213
Long-term debt (including amounts due within one year)(a)	2,966	2,044
Due to Related Parties, Noncurrent	267	264
Baltimore Gas and Electric Company [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		3
Long-term debt (including amounts due within one year)(a)	0	0
Due to Related Parties, Noncurrent	0	0
Baltimore Gas and Electric Company [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		210
Long-term debt (including amounts due within one year)(a)	2,966	2,044
Due to Related Parties, Noncurrent	0	0
Baltimore Gas and Electric Company [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		0
Long-term debt (including amounts due within one year)(a)	0	0
Due to Related Parties, Noncurrent	267	264
Pepco Holdings LLC [Member] | Predecessor [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Deferred Finance Costs, Net		49
Pepco Holdings LLC [Member] | Reported Value Measurement [Member] | Successor [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	517
Long-term debt (including amounts due within one year)(a)	6,044
Pepco Holdings LLC [Member] | Reported Value Measurement [Member] | Predecessor [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		958
Long-term debt (including amounts due within one year)(a)		5,279
Preferred Stock, Value, Issued		183
Pepco Holdings LLC [Member] | Estimate of Fair Value Measurement [Member] | Successor [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	517
Long-term debt (including amounts due within one year)(a)	6,292
Pepco Holdings LLC [Member] | Estimate of Fair Value Measurement [Member] | Predecessor [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		958
Long-term debt (including amounts due within one year)(a)		5,817
Preferred Stock, Value, Issued		183
Pepco Holdings LLC [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Successor [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	0
Long-term debt (including amounts due within one year)(a)	0
Pepco Holdings LLC [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Predecessor [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		0
Long-term debt (including amounts due within one year)(a)		0
Preferred Stock, Value, Issued		0
Pepco Holdings LLC [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Successor [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	517
Long-term debt (including amounts due within one year)(a)	5,698
Pepco Holdings LLC [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Predecessor [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		958
Long-term debt (including amounts due within one year)(a)		5,231
Preferred Stock, Value, Issued		0
Pepco Holdings LLC [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Successor [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	0
Long-term debt (including amounts due within one year)(a)	594
Pepco Holdings LLC [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Predecessor [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		0
Long-term debt (including amounts due within one year)(a)		586
Preferred Stock, Value, Issued		183
Potomac Electric Power Company [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Deferred Finance Costs, Net	30	31
Potomac Electric Power Company [Member] | Reported Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		64
Long-term debt (including amounts due within one year)(a)	2,350	2,351
Potomac Electric Power Company [Member] | Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		64
Long-term debt (including amounts due within one year)(a)	3,002	2,673
Potomac Electric Power Company [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		0
Long-term debt (including amounts due within one year)(a)	0	0
Potomac Electric Power Company [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		64
Long-term debt (including amounts due within one year)(a)	3,000	2,673
Potomac Electric Power Company [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		0
Long-term debt (including amounts due within one year)(a)	2	0
Delmarva Power and Light Company [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Deferred Finance Costs, Net	10	10
Delmarva Power and Light Company [Member] | Reported Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	17	105
Long-term debt (including amounts due within one year)(a)	1,265	1,265
Delmarva Power and Light Company [Member] | Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	17	105
Long-term debt (including amounts due within one year)(a)	1,378	1,288
Delmarva Power and Light Company [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	0	0
Long-term debt (including amounts due within one year)(a)	0	0
Delmarva Power and Light Company [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	17	105
Long-term debt (including amounts due within one year)(a)	1,277	1,185
Delmarva Power and Light Company [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	0	0
Long-term debt (including amounts due within one year)(a)	101	103
Atlantic City Electric Company [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Deferred Finance Costs, Net	6	6
Atlantic City Electric Company [Member] | Reported Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		5
Long-term debt (including amounts due within one year)(a)	1,167	1,201
Atlantic City Electric Company [Member] | Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		5
Long-term debt (including amounts due within one year)(a)	1,357	1,324
Atlantic City Electric Company [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		0
Long-term debt (including amounts due within one year)(a)	0	0
Atlantic City Electric Company [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		5
Long-term debt (including amounts due within one year)(a)	1,058	1,044
Atlantic City Electric Company [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value		0
Long-term debt (including amounts due within one year)(a)	$ 299	$ 280

Fair Value of Financial Asset68

Fair Value of Financial Assets and Liabilities - Fair Value Measurements of Assets and Liabilities, Recurring and Nonrecurring (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Mar. 23, 2016	Dec. 31, 2015
Fair Value Assets And Liabilities Measured On Recurring Basis Financial Statement Captions [Line Items]
Derivative Asset, Notional Amount		$ 1,073		$ 1,073			$ 1,236
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent		422		422			374
Derivative Liability, Current		222		222			205
Derivative, Collateral, Right to Reclaim Cash		64		64			52
Derivative Asset, Notional Amount		1,073		1,073			1,236
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value		(10)		(10)			(8)
Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		398		398			763
Cash and Cash Equivalents, Fair Value Disclosure		398		398			763
Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		197		197			178
Cash and Cash Equivalents, Fair Value Disclosure		197		197			178
Other Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		22		22
Cash and Cash Equivalents, Fair Value Disclosure		22		22
Nuclear Decommissioning Trust Fund Investments [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Net assets (liabilities) excluded from nuclear decommissioning trust fund investments		(69)		(69)			(3)
Pledged Assets For Zion Station Decommissioning [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Net assets (liabilities) excluded from nuclear decommissioning trust fund investments							1
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[1]	1,645		1,645			5,766
Cash and Cash Equivalents, Fair Value Disclosure	[1]	1,645		1,645			5,766
FinancialAssetsFairValueDisclosure1		14,622		14,622			18,556
Deferred Compensation Liability, Current and Noncurrent		(131)		(131)			(99)
Financial Liabilities Fair Value Disclosure		(775)		(775)			(678)
FinancialAssetLiabilitiesNetFairValueDisclosure1		13,847		13,847			17,878
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure		3,037		3,037			2,765
Fair Value, Measurements, Recurring [Member] | Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(625)		(625)			(563)
Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(5,358)		(5,358)			(6,827)
Fair Value, Measurements, Recurring [Member] | Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(102)		(102)			(127)
Fair Value, Measurements, Recurring [Member] | Interestrateandforeigncurrencyderivativeliabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(19)		(19)			(16)
Fair Value, Measurements, Recurring [Member] | EconomicHedgingInstrumentLiabilites1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(19)		(19)			(3)
Fair Value, Measurements, Recurring [Member] | ProprietaryTradingLiabilitiesInterestandFX [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(6)		(6)			(12)
Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability	[2]	4,835		4,835			6,391
Fair Value, Measurements, Recurring [Member] | Derivatives Designated As Hedging Instruments Liabilities [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(18)		(18)			(16)
Fair Value, Measurements, Recurring [Member] | Effect of Netting and Allocation of Collateral Interest Rate and FX Liabilities [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		24		24			15
Fair Value, Measurements, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[3]	11,145		11,145			10,345
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	[3]	2,969		2,969			2,660
Fair Value, Measurements, Recurring [Member] | Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[4]	183		183			311
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		5,893		5,893			4,902
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure		1,992		1,992			1,894
Fair Value, Measurements, Recurring [Member] | Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		138		138			125
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure		138		138			125
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		1,886		1,886			2,066
Fair Value, Measurements, Recurring [Member] | Foreign Government Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		50		50			61
Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		1,396		1,396			1,338
Fair Value, Measurements, Recurring [Member] | US Treasury And Government Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		30		30			8
Fair Value, Measurements, Recurring [Member] | CorporateDebtSecuritiesZoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		3		3			46
Fair Value, Measurements, Recurring [Member] | Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[5]	566		566			537
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	[5]	510		510			390
Fair Value, Measurements, Recurring [Member] | Other Fixed income Zoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							1
Fair Value, Measurements, Recurring [Member] | Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		306		306			35
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure		306		306			35
Fair Value, Measurements, Recurring [Member] | Economic hedge Interest and Currency [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		28		28			20
Fair Value, Measurements, Recurring [Member] | Commodity Derivative Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		1,369		1,369			2,069
Fair Value, Measurements, Recurring [Member] | State and municipal debt [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		268		268			326
Fair Value, Measurements, Recurring [Member] | Pledged Assets For Zion Station Decommissioning [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[6]	135		135			205
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	[6]	68		68			105
Fair Value, Measurements, Recurring [Member] | Cash Equivalent Zion [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		14		14			17
Cash and Cash Equivalents, Fair Value Disclosure		14		14			17
Fair Value, Measurements, Recurring [Member] | Equity Funds Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		1		1			6
Fair Value, Measurements, Recurring [Member] | Fixed Income Securities Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		33		33			55
Fair Value, Measurements, Recurring [Member] | MiddleMarketLending Zoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		87		87			127
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure		68		68			105
Fair Value, Measurements, Recurring [Member] | Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		4,166		4,166			4,328
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure		510		510			390
Fair Value, Measurements, Recurring [Member] | Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		459		459			428
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure		23		23
Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		232		232			84
Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		83		83
Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		14		14
Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		50		50			48
Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		85		85			36
Fair Value, Measurements, Recurring [Member] | Other Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		42		42			33
Fair Value, Measurements, Recurring [Member] | Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		98		98			130
Fair Value, Measurements, Recurring [Member] | Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	[2]	(4,351)		(4,351)			(5,157)
Fair Value, Measurements, Recurring [Member] | Interest rate and foreign currency derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		54		54			54
Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		39		39			25
Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		5,622		5,622			7,096
Fair Value, Measurements, Recurring [Member] | Proprietary Trading Interest and Currency Derivative [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		8		8			15
Fair Value, Measurements, Recurring [Member] | Effectsofnettingandallocationofcollateral1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		(21)		(21)			(6)
Fair Value, Measurements, Recurring [Member] | Other [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							216
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure							216
Fair Value, Inputs, Level 1 [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Collateral received from counterparties, net of collateral paid to counterparties		85		85			476
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[1]	1,645		1,645			5,766
Cash and Cash Equivalents, Fair Value Disclosure	[1]	1,645		1,645			5,766
FinancialAssetsFairValueDisclosure1		6,882		6,882			10,372
Deferred Compensation Liability, Current and Noncurrent		0		0			0
Financial Liabilities Fair Value Disclosure		(33)		(33)			25
FinancialAssetLiabilitiesNetFairValueDisclosure1		6,849		6,849			10,397
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(35)		(35)			25
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(1,037)		(1,037)			(2,382)
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(10)		(10)			(33)
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Interestrateandforeigncurrencyderivativeliabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		2		2			0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | EconomicHedgingInstrumentLiabilites1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		0		0			0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | ProprietaryTradingLiabilitiesInterestandFX [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(6)		(6)			(12)
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability	[2]	1,012		1,012			2,440
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Derivatives Designated As Hedging Instruments Liabilities [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		0		0			0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Effect of Netting and Allocation of Collateral Interest Rate and FX Liabilities [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		8		8			12
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[3]	5,092		5,092			4,550
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[4]	163		163			219
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		3,566		3,566			3,008
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Government Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		1,363		1,363			1,323
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury And Government Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		28		28			6
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | CorporateDebtSecuritiesZoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[5]	0		0			0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Other Fixed income Zoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Economic hedge Interest and Currency [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		0		0			0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Derivative Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		(33)		(33)			(6)
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | State and municipal debt [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Pledged Assets For Zion Station Decommissioning [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[6]	42		42			7
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalent Zion [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		14		14			0
Cash and Cash Equivalents, Fair Value Disclosure		14		14			0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Funds Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			1
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Securities Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		28		28			6
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | MiddleMarketLending Zoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		1,363		1,363			1,323
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		133		133			48
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		83		83
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		50		50			48
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Other Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		11		11			36
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	[2]	(928)		(928)			(1,964)
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Interest rate and foreign currency derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		3		3			7
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		0		0			0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		884		884			1,922
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Interest and Currency Derivative [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		7		7			10
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Effectsofnettingandallocationofcollateral1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		(4)		(4)			(3)
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Other [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							0
Fair Value, Inputs, Level 2 [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Collateral received from counterparties, net of collateral paid to counterparties		250		250			557
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[1]	0		0			0
Cash and Cash Equivalents, Fair Value Disclosure	[1]	0		0			0
FinancialAssetsFairValueDisclosure1		2,840		2,840			3,521
Deferred Compensation Liability, Current and Noncurrent		(131)		(131)			(99)
Financial Liabilities Fair Value Disclosure		(345)		(345)			(334)
FinancialAssetLiabilitiesNetFairValueDisclosure1		2,495		2,495			3,187
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(193)		(193)			(219)
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(2,917)		(2,917)			(3,348)
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(53)		(53)			(57)
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Interestrateandforeigncurrencyderivativeliabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(21)		(21)			(16)
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | EconomicHedgingInstrumentLiabilites1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(19)		(19)			(3)
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | ProprietaryTradingLiabilitiesInterestandFX [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		0		0			0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability	[2]	2,777		2,777			3,186
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Derivatives Designated As Hedging Instruments Liabilities [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(18)		(18)			(16)
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Effect of Netting and Allocation of Collateral Interest Rate and FX Liabilities [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		16		16			3
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[3]	2,391		2,391			2,465
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[4]	20		20			92
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		335		335			0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		1,629		1,629			1,824
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Government Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		50		50			61
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		33		33			15
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury And Government Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		2		2			2
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | CorporateDebtSecuritiesZoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		3		3			46
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[5]	56		56			147
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Other Fixed income Zoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							1
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Economic hedge Interest and Currency [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		28		28			20
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Derivative Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		314		314			902
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | State and municipal debt [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		268		268			326
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Pledged Assets For Zion Station Decommissioning [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[6]	6		6			71
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalent Zion [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		0		0			17
Cash and Cash Equivalents, Fair Value Disclosure		0		0			17
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Funds Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		1		1			5
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Securities Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		5		5			49
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | MiddleMarketLending Zoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		2,036		2,036			2,373
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		78		78			36
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		14		14
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		64		64			36
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Other Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		51		51			64
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	[2]	(2,527)		(2,527)			(2,629)
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Interest rate and foreign currency derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		51		51			47
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		39		39			25
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		2,790		2,790			3,467
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Interest and Currency Derivative [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		1		1			5
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Effectsofnettingandallocationofcollateral1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		(17)		(17)			(3)
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Other [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							0
Fair Value, Inputs, Level 3 [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Collateral received from counterparties, net of collateral paid to counterparties		150		150			201
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[1]	0		0			0
Cash and Cash Equivalents, Fair Value Disclosure	[1]	0		0			0
FinancialAssetsFairValueDisclosure1		1,863		1,863			1,898
Deferred Compensation Liability, Current and Noncurrent		0		0			0
Financial Liabilities Fair Value Disclosure		(397)		(397)			(369)
FinancialAssetLiabilitiesNetFairValueDisclosure1		1,466		1,466			1,529
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(397)		(397)			(369)
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(1,404)		(1,404)			(1,097)
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(39)		(39)			(37)
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Interestrateandforeigncurrencyderivativeliabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | EconomicHedgingInstrumentLiabilites1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | ProprietaryTradingLiabilitiesInterestandFX [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability	[2]	1,046		1,046			765
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Derivatives Designated As Hedging Instruments Liabilities [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Effect of Netting and Allocation of Collateral Interest Rate and FX Liabilities [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[3]	693		693			670
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[4]	0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		257		257			242
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Government Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury And Government Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | CorporateDebtSecuritiesZoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[5]	0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Other Fixed income Zoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Economic hedge Interest and Currency [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Derivative Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		1,088		1,088			1,173
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | State and municipal debt [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Pledged Assets For Zion Station Decommissioning [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[6]	19		19			22
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalent Zion [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		0		0			0
Cash and Cash Equivalents, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Funds Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Securities Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | MiddleMarketLending Zoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		19		19			22
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		257		257			242
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		436		436			428
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		21		21			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		21		21			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Other Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		42		42			33
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		36		36			30
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	[2]	(896)		(896)			(564)
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Interest rate and foreign currency derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		1,948		1,948			1,707
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Interest and Currency Derivative [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Effectsofnettingandallocationofcollateral1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		0		0			0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Other [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							0
Exelon Generation Co L L C [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Financial Statement Captions [Line Items]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings		190	$ 229	579	$ 623
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent		197		197			150
Derivative Liability, Current		203		203			182
Exelon Generation Co L L C [Member] | Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(102)		(102)
Exelon Generation Co L L C [Member] | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		282		282			329
Cash and Cash Equivalents, Fair Value Disclosure		282		282			329
Exelon Generation Co L L C [Member] | Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		161		161			121
Cash and Cash Equivalents, Fair Value Disclosure		161		161			121
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[1]	94		94			104
Cash and Cash Equivalents, Fair Value Disclosure	[1]	94		94			104
FinancialAssetsFairValueDisclosure1		12,847		12,847			12,815
Deferred Compensation Liability, Current and Noncurrent		(32)		(32)			(30)
Financial Liabilities Fair Value Disclosure		(432)		(432)			(362)
FinancialAssetLiabilitiesNetFairValueDisclosure1		12,415		12,415			12,453
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure		3,037		3,037			2,765
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(381)		(381)			(316)
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(5,114)		(5,114)			(6,580)
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability							(127)
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Interestrateandforeigncurrencyderivativeliabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(19)		(19)			(16)
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | EconomicHedgingInstrumentLiabilites1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(19)		(19)			(3)
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | ProprietaryTradingLiabilitiesInterestandFX [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(6)		(6)			(12)
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability	[2]	4,835		4,835			6,391
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Derivatives Designated As Hedging Instruments Liabilities [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(18)		(18)			(16)
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Effect of Netting and Allocation of Collateral Interest Rate and FX Liabilities [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		24		24			15
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[3]	11,145		11,145			10,345
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	[3]	2,969		2,969			2,660
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[4]	183		183			311
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		5,893		5,893			4,902
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure		1,992		1,992			1,894
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		138		138			125
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure		138		138			125
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		1,886		1,886			2,066
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Government Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		50		50			61
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		1,396		1,396			1,338
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury And Government Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		30		30			8
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | CorporateDebtSecuritiesZoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		3		3			46
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[5]	566		566			537
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	[5]	510		510			390
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Other Fixed income Zoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							1
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		306		306			35
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure		306		306			35
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Economic hedge Interest and Currency [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		28		28			20
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Derivative Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		1,369		1,369			2,069
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | State and municipal debt [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		268		268			326
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Pledged Assets For Zion Station Decommissioning [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[6]	135		135			205
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	[6]	68		68			105
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalent Zion [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		14		14			17
Cash and Cash Equivalents, Fair Value Disclosure		14		14			17
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Equity Funds Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		1		1			6
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Securities Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		33		33			55
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | MiddleMarketLending Zoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		87		87			127
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure		68		68			105
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		4,166		4,166			4,328
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure		510		510			390
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		459		459			428
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure		23		23
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		47		47			30
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		10		10
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		19		19			17
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		18		18			13
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Other Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		42		42			33
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		98		98			130
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	[2]	(4,350)		(4,350)			(5,157)
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Interest rate and foreign currency derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		15		15			29
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		5,621		5,621			7,096
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Interest and Currency Derivative [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		8		8			15
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Effectsofnettingandallocationofcollateral1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		(21)		(21)			(6)
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Other [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							216
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure							216
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[1]	94		94			104
Cash and Cash Equivalents, Fair Value Disclosure	[1]	94		94			104
FinancialAssetsFairValueDisclosure1		5,227		5,227			4,679
Deferred Compensation Liability, Current and Noncurrent		0		0			0
Financial Liabilities Fair Value Disclosure		(33)		(33)			25
FinancialAssetLiabilitiesNetFairValueDisclosure1		5,194		5,194			4,704
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(35)		(35)			25
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(1,037)		(1,037)			(2,382)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(10)		(10)			(33)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Interestrateandforeigncurrencyderivativeliabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		2		2			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | EconomicHedgingInstrumentLiabilites1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | ProprietaryTradingLiabilitiesInterestandFX [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(6)		(6)			(12)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability	[2]	1,012		1,012			2,440
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Derivatives Designated As Hedging Instruments Liabilities [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Effect of Netting and Allocation of Collateral Interest Rate and FX Liabilities [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		8		8			12
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[3]	5,092		5,092			4,550
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[4]	163		163			219
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		3,566		3,566			3,008
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Government Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		1,363		1,363			1,323
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury And Government Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		28		28			6
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | CorporateDebtSecuritiesZoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[5]	0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Other Fixed income Zoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Economic hedge Interest and Currency [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Derivative Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		(33)		(33)			(6)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | State and municipal debt [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Pledged Assets For Zion Station Decommissioning [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[6]	42		42			7
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalent Zion [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		14		14			0
Cash and Cash Equivalents, Fair Value Disclosure		14		14			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Funds Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			1
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Securities Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		28		28			6
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | MiddleMarketLending Zoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		1,363		1,363			1,323
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		29		29			17
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		10		10
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		19		19			17
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Other Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		11		11			36
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	[2]	(927)		(927)			(1,964)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Interest rate and foreign currency derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		3		3			7
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		883		883			1,922
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Interest and Currency Derivative [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		7		7			10
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Effectsofnettingandallocationofcollateral1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		(4)		(4)			(3)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Other [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[1]	0		0			0
Cash and Cash Equivalents, Fair Value Disclosure	[1]	0		0			0
FinancialAssetsFairValueDisclosure1		2,741		2,741			3,473
Deferred Compensation Liability, Current and Noncurrent		(32)		(32)			(30)
Financial Liabilities Fair Value Disclosure		(246)		(246)			(265)
FinancialAssetLiabilitiesNetFairValueDisclosure1		2,495		2,495			3,208
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(193)		(193)			(219)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(2,917)		(2,917)			(3,348)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(53)		(53)			(57)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Interestrateandforeigncurrencyderivativeliabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(21)		(21)			(16)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | EconomicHedgingInstrumentLiabilites1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(19)		(19)			(3)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | ProprietaryTradingLiabilitiesInterestandFX [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability	[2]	2,777		2,777			3,186
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Derivatives Designated As Hedging Instruments Liabilities [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(18)		(18)			(16)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Effect of Netting and Allocation of Collateral Interest Rate and FX Liabilities [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		16		16			3
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[3]	2,391		2,391			2,465
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[4]	20		20			92
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		335		335			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		1,629		1,629			1,824
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Government Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		50		50			61
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		33		33			15
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury And Government Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		2		2			2
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | CorporateDebtSecuritiesZoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		3		3			46
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[5]	56		56			147
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Other Fixed income Zoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							1
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Economic hedge Interest and Currency [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		28		28			20
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Derivative Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		314		314			902
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | State and municipal debt [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		268		268			326
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Pledged Assets For Zion Station Decommissioning [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[6]	6		6			71
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalent Zion [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		0		0			17
Cash and Cash Equivalents, Fair Value Disclosure		0		0			17
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Funds Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		1		1			5
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Securities Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		5		5			49
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | MiddleMarketLending Zoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		2,036		2,036			2,373
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		18		18			13
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		18		18			13
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Other Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		51		51			64
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	[2]	(2,527)		(2,527)			(2,629)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Interest rate and foreign currency derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		12		12			22
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		2,790		2,790			3,467
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Interest and Currency Derivative [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		1		1			5
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Effectsofnettingandallocationofcollateral1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		(17)		(17)			(3)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Other [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[1]	0		0			0
Cash and Cash Equivalents, Fair Value Disclosure	[1]	0		0			0
FinancialAssetsFairValueDisclosure1		1,842		1,842			1,898
Deferred Compensation Liability, Current and Noncurrent		0		0			0
Financial Liabilities Fair Value Disclosure		(153)		(153)			(122)
FinancialAssetLiabilitiesNetFairValueDisclosure1		1,689		1,689			1,776
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(153)		(153)			(122)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(1,160)		(1,160)			(850)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		(39)		(39)			(37)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Interestrateandforeigncurrencyderivativeliabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | EconomicHedgingInstrumentLiabilites1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | ProprietaryTradingLiabilitiesInterestandFX [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability	[2]	1,046		1,046			765
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Derivatives Designated As Hedging Instruments Liabilities [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Effect of Netting and Allocation of Collateral Interest Rate and FX Liabilities [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[3]	693		693			670
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[4]	0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		257		257			242
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Government Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury And Government Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | CorporateDebtSecuritiesZoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Other Fixed Income [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[5]	0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Other Fixed income Zoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Real Estate Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Economic hedge Interest and Currency [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Derivative Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		1,088		1,088			1,173
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | State and municipal debt [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Pledged Assets For Zion Station Decommissioning [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	[6]	19		19			22
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalent Zion [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		0		0			0
Cash and Cash Equivalents, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Funds Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Securities Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | MiddleMarketLending Zoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		19		19			22
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		257		257			242
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Middle Market Lending [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		436		436			428
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Other Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		42		42			33
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		36		36			30
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	[2]	(896)		(896)			(564)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Interest rate and foreign currency derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		1,948		1,948			1,707
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Interest and Currency Derivative [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Effectsofnettingandallocationofcollateral1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		0		0			0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Other [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							0
Pepco Holdings LLC [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Financial Statement Captions [Line Items]
Derivative, Fair Value, Net						$ 0
Pepco Holdings LLC [Member] | Successor [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Financial Statement Captions [Line Items]
Derivative, Fair Value, Net		0		0
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset		0		0
Derivative Liability		0		0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent		0		0
Derivative Liability, Current		0		0
Pepco Holdings LLC [Member] | Predecessor [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Financial Statement Captions [Line Items]
Derivative, Fair Value, Net							18
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset							18
Derivative Liability							0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent							0
Derivative Liability, Current							0
Pepco Holdings LLC [Member] | Predecessor [Member] | Rabbi Trust Investments [Member]
U.S. Treasury and agencies
Derivative Asset, Fair Value, Amount Not Offset Against Collateral							18
Pepco Holdings LLC [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		347		347
Cash and Cash Equivalents, Fair Value Disclosure		347		347
Derivative Asset		1		1
FinancialAssetsFairValueDisclosure1		477		477
Derivative Liability		0		0
Deferred Compensation Liability, Current and Noncurrent		(28)		(28)
Financial Liabilities Fair Value Disclosure		(28)		(28)
FinancialAssetLiabilitiesNetFairValueDisclosure1		449		449
U.S. Treasury and agencies
Collateral Amount Offset Against Fair Value Of Derivative Current Asset		(1)		(1)
Pepco Holdings LLC [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure		0		0
Pepco Holdings LLC [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent		0		0
Pepco Holdings LLC [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		130		130
Pepco Holdings LLC [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		73		73
Pepco Holdings LLC [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		14		14
Pepco Holdings LLC [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		43		43
Pepco Holdings LLC [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents							42
Cash and Cash Equivalents, Fair Value Disclosure							42
FinancialAssetsFairValueDisclosure1							133
Derivative Liability							0
Deferred Compensation Liability, Current and Noncurrent							(30)
Financial Liabilities Fair Value Disclosure							(30)
FinancialAssetLiabilitiesNetFairValueDisclosure1							103
U.S. Treasury and agencies
Derivative Asset, Fair Value, Amount Not Offset Against Collateral							18
Pepco Holdings LLC [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure							(2)
Pepco Holdings LLC [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent							(2)
Pepco Holdings LLC [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							73
Pepco Holdings LLC [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							12
Pepco Holdings LLC [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							15
Pepco Holdings LLC [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							46
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		20		20			16
Cash and Cash Equivalents, Fair Value Disclosure		20		20			16
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Other Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		19		19			18
Cash and Cash Equivalents, Fair Value Disclosure		19		19			18
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		347		347
Cash and Cash Equivalents, Fair Value Disclosure		347		347
Derivative Asset		1		1
FinancialAssetsFairValueDisclosure1		420		420
Derivative Liability		0		0
Deferred Compensation Liability, Current and Noncurrent		0		0
Financial Liabilities Fair Value Disclosure		0		0
FinancialAssetLiabilitiesNetFairValueDisclosure1		420		420
U.S. Treasury and agencies
Collateral Amount Offset Against Fair Value Of Derivative Current Asset		(1)		(1)
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure		0		0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent		0		0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		73		73
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		73		73
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents							42
Cash and Cash Equivalents, Fair Value Disclosure							42
FinancialAssetsFairValueDisclosure1							54
Derivative Liability							0
Deferred Compensation Liability, Current and Noncurrent							0
Financial Liabilities Fair Value Disclosure							0
FinancialAssetLiabilitiesNetFairValueDisclosure1							54
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure							(2)
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent							(2)
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							12
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							12
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		0		0
Cash and Cash Equivalents, Fair Value Disclosure		0		0
FinancialAssetsFairValueDisclosure1		36		36
Derivative Liability		0		0
Deferred Compensation Liability, Current and Noncurrent		(28)		(28)
Financial Liabilities Fair Value Disclosure		(28)		(28)
FinancialAssetLiabilitiesNetFairValueDisclosure1		8		8
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure		0		0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent		0		0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		36		36
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		14		14
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		22		22
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents							0
Cash and Cash Equivalents, Fair Value Disclosure							0
Investments, Fair Value Disclosure							0
FinancialAssetsFairValueDisclosure1							42
Derivative Liability							0
Deferred Compensation Liability, Current and Noncurrent							(30)
Financial Liabilities Fair Value Disclosure							(30)
FinancialAssetLiabilitiesNetFairValueDisclosure1							12
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure							0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent							0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							42
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							15
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							27
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		0		0
Cash and Cash Equivalents, Fair Value Disclosure		0		0
FinancialAssetsFairValueDisclosure1		21		21
Derivative Liability		0		0
Deferred Compensation Liability, Current and Noncurrent		0		0
Financial Liabilities Fair Value Disclosure		0		0
FinancialAssetLiabilitiesNetFairValueDisclosure1		21		21
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure		0		0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent		0		0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		21		21
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		21		21
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents							0
Cash and Cash Equivalents, Fair Value Disclosure							0
Investments, Fair Value Disclosure							0
FinancialAssetsFairValueDisclosure1							37
Derivative Liability							0
Deferred Compensation Liability, Current and Noncurrent							0
Financial Liabilities Fair Value Disclosure							0
FinancialAssetLiabilitiesNetFairValueDisclosure1							37
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure							0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent							0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Derivative, Name [Domain]
U.S. Treasury and agencies
Derivative Asset, Fair Value, Amount Not Offset Against Collateral							18
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Derivative Financial Instruments, Assets [Member]
U.S. Treasury and agencies
Derivative Asset, Fair Value, Amount Not Offset Against Collateral							18
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							19
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Predecessor [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							19
PECO Energy Co [Member] | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		27		27			27
Cash and Cash Equivalents, Fair Value Disclosure		27		27			27
PECO Energy Co [Member] | Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		1		1
Cash and Cash Equivalents, Fair Value Disclosure		1		1
PECO Energy Co [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[7]	521		521			271
Cash and Cash Equivalents, Fair Value Disclosure	[7]	521		521			271
FinancialAssetsFairValueDisclosure1		539		539			291
Deferred Compensation Liability, Current and Noncurrent		(10)		(10)			(12)
Financial Liabilities Fair Value Disclosure		(10)		(10)			(12)
FinancialAssetLiabilitiesNetFairValueDisclosure1		529		529			279
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	[8]	0		0			0
PECO Energy Co [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		18		18			20
PECO Energy Co [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		7		7			8
PECO Energy Co [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		11		11			12
PECO Energy Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[7]	521		521			271
Cash and Cash Equivalents, Fair Value Disclosure	[7]	521		521			271
FinancialAssetsFairValueDisclosure1		528		528			279
Deferred Compensation Liability, Current and Noncurrent		0		0			0
Financial Liabilities Fair Value Disclosure		0		0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1		528		528			279
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	[8]	0		0			0
PECO Energy Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		7		7			8
PECO Energy Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		7		7			8
PECO Energy Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
PECO Energy Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[7]	0		0			0
Cash and Cash Equivalents, Fair Value Disclosure	[7]	0		0			0
FinancialAssetsFairValueDisclosure1		11		11			12
Deferred Compensation Liability, Current and Noncurrent		(10)		(10)			(12)
Financial Liabilities Fair Value Disclosure		(10)		(10)			(12)
FinancialAssetLiabilitiesNetFairValueDisclosure1		1		1			0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	[8]	0		0			0
PECO Energy Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		11		11			12
PECO Energy Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
PECO Energy Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		11		11			12
PECO Energy Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[7]	0		0			0
Cash and Cash Equivalents, Fair Value Disclosure	[7]	0		0			0
FinancialAssetsFairValueDisclosure1		0		0			0
Deferred Compensation Liability, Current and Noncurrent		0		0			0
Financial Liabilities Fair Value Disclosure		0		0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1		0		0			0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	[8]	0		0			0
PECO Energy Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
PECO Energy Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
PECO Energy Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Baltimore Gas and Electric Company [Member] | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		13		13			6
Cash and Cash Equivalents, Fair Value Disclosure		13		13			6
Baltimore Gas and Electric Company [Member] | Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		2		2			2
Cash and Cash Equivalents, Fair Value Disclosure		2		2			2
Baltimore Gas and Electric Company [Member] | Other Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		3		3
Cash and Cash Equivalents, Fair Value Disclosure		3		3
Baltimore Gas and Electric Company [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[7]	375		375			25
Cash and Cash Equivalents, Fair Value Disclosure	[7]	375		375			25
FinancialAssetsFairValueDisclosure1		379		379			29
Deferred Compensation Liability, Current and Noncurrent		(4)		(4)			(4)
Financial Liabilities Fair Value Disclosure		(4)		(4)			(4)
FinancialAssetLiabilitiesNetFairValueDisclosure1		375		375			25
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	[8]	0		0			0
Baltimore Gas and Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		4		4			4
Baltimore Gas and Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		4		4			4
Baltimore Gas and Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[7]	375		375			25
Cash and Cash Equivalents, Fair Value Disclosure	[7]	375		375			25
FinancialAssetsFairValueDisclosure1		379		379			29
Deferred Compensation Liability, Current and Noncurrent		0		0			0
Financial Liabilities Fair Value Disclosure		0		0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1		379		379			29
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	[8]	0		0			0
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		4		4			4
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		4		4			4
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[7]	0		0			0
Cash and Cash Equivalents, Fair Value Disclosure	[7]	0		0			0
FinancialAssetsFairValueDisclosure1		0		0			0
Deferred Compensation Liability, Current and Noncurrent		(4)		(4)			(4)
Financial Liabilities Fair Value Disclosure		(4)		(4)			(4)
FinancialAssetLiabilitiesNetFairValueDisclosure1		(4)		(4)			(4)
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	[8]	0		0			0
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[7]	0		0			0
Cash and Cash Equivalents, Fair Value Disclosure	[7]	0		0			0
FinancialAssetsFairValueDisclosure1		0		0			0
Deferred Compensation Liability, Current and Noncurrent		0		0			0
Financial Liabilities Fair Value Disclosure		0		0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1		0		0			0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	[8]	0		0			0
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Potomac Electric Power Company [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		127		127			2
Cash and Cash Equivalents, Fair Value Disclosure		127		127			2
FinancialAssetsFairValueDisclosure1		227		227			70
Derivative Liability							0
Deferred Compensation Liability, Current and Noncurrent		(5)		(5)			(6)
Financial Liabilities Fair Value Disclosure		(5)		(5)			(6)
FinancialAssetLiabilitiesNetFairValueDisclosure1		222		222			64
Potomac Electric Power Company [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure							0
Potomac Electric Power Company [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent							0
Potomac Electric Power Company [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		100		100			68
Potomac Electric Power Company [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		43		43			11
Potomac Electric Power Company [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		14		14			15
Potomac Electric Power Company [Member] | Fair Value, Measurements, Recurring [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		43		43			42
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		127		127			2
Cash and Cash Equivalents, Fair Value Disclosure		127		127			2
Investments, Fair Value Disclosure		0		0
FinancialAssetsFairValueDisclosure1		170		170			13
Derivative Liability							0
Deferred Compensation Liability, Current and Noncurrent		0		0			0
Financial Liabilities Fair Value Disclosure		0		0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1		170		170			13
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure							0
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent							0
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		8		8			5
Cash and Cash Equivalents, Fair Value Disclosure		8		8			5
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		43		43			11
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		43		43			11
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							0
FinancialAssetsFairValueDisclosure1		36		36			38
Derivative Liability							0
Deferred Compensation Liability, Current and Noncurrent		(5)		(5)			(6)
Financial Liabilities Fair Value Disclosure		(5)		(5)			(6)
FinancialAssetLiabilitiesNetFairValueDisclosure1		31		31			32
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure							0
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent							0
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		36		36			38
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		14		14			15
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		22		22			23
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure							0
FinancialAssetsFairValueDisclosure1		21		21			19
Derivative Liability							0
Deferred Compensation Liability, Current and Noncurrent		0		0			0
Financial Liabilities Fair Value Disclosure		0		0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1		21		21			19
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure							0
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent							0
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		21		21			19
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		21		21			19
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Delmarva Power and Light Company [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		0		0			0
Cash and Cash Equivalents, Fair Value Disclosure		0		0			0
Derivative Asset		1		1
FinancialAssetsFairValueDisclosure1		0		0			0
Derivative Liability							0
Deferred Compensation Liability, Current and Noncurrent		(1)		(1)			(1)
Financial Liabilities Fair Value Disclosure		(1)		(1)			(1)
FinancialAssetLiabilitiesNetFairValueDisclosure1		(1)		(1)			(1)
U.S. Treasury and agencies
Collateral Amount Offset Against Fair Value Of Derivative Current Asset		(1)		(1)
Delmarva Power and Light Company [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure							(2)
Delmarva Power and Light Company [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent							(2)
Delmarva Power and Light Company [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Delmarva Power and Light Company [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Delmarva Power and Light Company [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Delmarva Power and Light Company [Member] | Fair Value, Measurements, Recurring [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		0		0			0
Cash and Cash Equivalents, Fair Value Disclosure		0		0			0
Investments, Fair Value Disclosure		0		0			0
Derivative Asset		1		1
FinancialAssetsFairValueDisclosure1		0		0			0
Derivative Liability							0
Deferred Compensation Liability, Current and Noncurrent		0		0			0
Financial Liabilities Fair Value Disclosure		0		0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1		0		0			0
U.S. Treasury and agencies
Collateral Amount Offset Against Fair Value Of Derivative Current Asset		(1)		(1)
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure							(2)
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent							(2)
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		4		4			5
Cash and Cash Equivalents, Fair Value Disclosure		4		4			5
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		0		0			0
Cash and Cash Equivalents, Fair Value Disclosure		0		0			0
Investments, Fair Value Disclosure							0
FinancialAssetsFairValueDisclosure1		0		0			0
Derivative Liability							0
Deferred Compensation Liability, Current and Noncurrent		(1)		(1)			(1)
Financial Liabilities Fair Value Disclosure		(1)		(1)			(1)
FinancialAssetLiabilitiesNetFairValueDisclosure1		(1)		(1)			(1)
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure							0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent							0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		0		0			0
Cash and Cash Equivalents, Fair Value Disclosure		0		0			0
Investments, Fair Value Disclosure							0
FinancialAssetsFairValueDisclosure1		0		0			0
Derivative Liability							0
Deferred Compensation Liability, Current and Noncurrent		0		0			0
Financial Liabilities Fair Value Disclosure		0		0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1		0		0			0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure							0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent							0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Atlantic City Electric Company [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		194		194			30
Cash and Cash Equivalents, Fair Value Disclosure		194		194			30
FinancialAssetsFairValueDisclosure1		194		194			30
Derivative Liability							0
Deferred Compensation Liability, Current and Noncurrent		0		0			0
Financial Liabilities Fair Value Disclosure		0		0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1		194		194			30
Atlantic City Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure							0
Atlantic City Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent							0
Atlantic City Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Atlantic City Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Atlantic City Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Atlantic City Electric Company [Member] | Fair Value, Measurements, Recurring [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		194		194			30
Cash and Cash Equivalents, Fair Value Disclosure		194		194			30
Investments, Fair Value Disclosure		0		0			0
FinancialAssetsFairValueDisclosure1		194		194			30
Derivative Liability							0
Deferred Compensation Liability, Current and Noncurrent		0		0			0
Financial Liabilities Fair Value Disclosure		0		0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1		194		194			30
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure							0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent							0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		5		5			3
Cash and Cash Equivalents, Fair Value Disclosure		5		5			3
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Other Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		19		19			18
Cash and Cash Equivalents, Fair Value Disclosure		19		19			18
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		0		0			0
Cash and Cash Equivalents, Fair Value Disclosure		0		0			0
Investments, Fair Value Disclosure							0
FinancialAssetsFairValueDisclosure1		0		0			0
Derivative Liability							0
Deferred Compensation Liability, Current and Noncurrent		0		0			0
Financial Liabilities Fair Value Disclosure		0		0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1		0		0			0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure							0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent							0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		0		0			0
Cash and Cash Equivalents, Fair Value Disclosure		0		0			0
Investments, Fair Value Disclosure							0
FinancialAssetsFairValueDisclosure1		0		0			0
Derivative Liability							0
Deferred Compensation Liability, Current and Noncurrent		0		0			0
Financial Liabilities Fair Value Disclosure		0		0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1		0		0			0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedging Instrument Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Financial Liabilities Fair Value Disclosure							0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Effects of Netting and Allocation of Collateral Liabilites [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent							0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Surrender Value [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Atlantic City Electric Company [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Successor [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0
Commonwealth Edison Co [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent		225		225			224
Derivative Liability, Current		19		19			23
Commonwealth Edison Co [Member] | Cash and Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		44		44			38
Cash and Cash Equivalents, Fair Value Disclosure		44		44			38
Commonwealth Edison Co [Member] | Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents		2		2			2
Cash and Cash Equivalents, Fair Value Disclosure		2		2			2
Commonwealth Edison Co [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[7]	0		0			29
Cash and Cash Equivalents, Fair Value Disclosure	[7]	0		0			29
FinancialAssetsFairValueDisclosure1		0		0			29
Deferred Compensation Liability, Current and Noncurrent		(8)		(8)			(8)
Financial Liabilities Fair Value Disclosure		(252)		(252)			(255)
FinancialAssetLiabilitiesNetFairValueDisclosure1		(252)		(252)			226
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	[8]	(244)		(244)			247
Commonwealth Edison Co [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Commonwealth Edison Co [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Commonwealth Edison Co [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[7]	0		0			29
Cash and Cash Equivalents, Fair Value Disclosure	[7]	0		0			29
FinancialAssetsFairValueDisclosure1		0		0			29
Deferred Compensation Liability, Current and Noncurrent		0		0			0
Financial Liabilities Fair Value Disclosure		0		0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1		0		0			29
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	[8]	0		0			0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[7]	0		0			0
Cash and Cash Equivalents, Fair Value Disclosure	[7]	0		0			0
FinancialAssetsFairValueDisclosure1		0		0			0
Deferred Compensation Liability, Current and Noncurrent		(8)		(8)			(8)
Financial Liabilities Fair Value Disclosure		(8)		(8)			(8)
FinancialAssetLiabilitiesNetFairValueDisclosure1		(8)		(8)			(8)
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	[8]	0		0			0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	[7]	0		0			0
Cash and Cash Equivalents, Fair Value Disclosure	[7]	0		0			0
FinancialAssetsFairValueDisclosure1		0		0			0
Deferred Compensation Liability, Current and Noncurrent		0		0			0
Financial Liabilities Fair Value Disclosure		(244)		(244)			(247)
FinancialAssetLiabilitiesNetFairValueDisclosure1		(244)		(244)			(247)
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	[8]	(244)		(244)			247
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Rabbi Trust Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		0		0			0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure		$ 0		$ 0			$ 0
[1]	Generation excludes cash of $282 million and $329 million at September 30, 2016 and December 31, 2015 and restricted cash of $161 million and $121 million at September 30, 2016 and December 31, 2015. Exelon excludes cash of $398 million and $763 million at September 30, 2016 and December 31, 2015 and restricted cash of $197 million and $178 million at September 30, 2016 and December 31, 2015 and includes long term restricted cash of $22 million at September 30, 2016, which is reported in other deferred debits on the balance sheet.
[2]	Collateral posted to/(received) from counterparties totaled $85 million, $250 million and $150 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of September 30, 2016. Collateral posted (received) from counterparties, net of collateral paid to counterparties, totaled $476 million, $557 million and $201 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of December 31, 2015.
[3]	Excludes net liabilities of $(69) million and $(3) million at September 30, 2016 and December 31, 2015, respectively. These items consist of receivables related to pending securities sales, interest and dividend receivables, repurchase agreement obligations, and payables related to pending securities purchases. The repurchase agreements are generally short-term in nature with durations generally of 30 days or less.
[4]	Includes $64 million and $52 million of cash received from outstanding repurchase agreements at September 30, 2016 and December 31, 2015, respectively, and is offset by an obligation to repay upon settlement of the agreement as discussed in (d) below.
[5]	Includes derivative instruments of $(10) million and $(8) million, which have a total notional amount of $1,073 million and $1,236 million at September 30, 2016 and December 31, 2015, respectively. The notional principal amounts for these instruments provide one measure of the transaction volume outstanding as of the periods ended and do not represent the amount of the company's exposure to credit or market loss.
[6]	Excludes net assets of less than $1 million and $1 million at September 30, 2016 and December 31, 2015, respectively. These items consist of receivables related to pending securities sales, interest and dividend receivables, and payables related to pending securities purchases.
[7]	ComEd excludes cash of $44 million and $38 million at September 30, 2016 and December 31, 2015 and restricted cash of $2 million and $2 million at September 30, 2016 and December 31, 2015. PECO excludes cash of $27 million and $27 million at September 30, 2016 and December 31, 2015 and $1 million of restricted cash at September 30, 2016. BGE excludes cash of $13 million and $6 million at September 30, 2016 and December 31, 2015 and restricted cash of $2 million and $2 million at September 30, 2016 and December 31, 2015 and includes long term restricted cash of $3 million at September 30, 2016, which is reported in other deferred debits on the balance sheet.
[8]	The Level 3 balance consists of the current and noncurrent liability of $19 million and $225 million, respectively, at September 30, 2016, and $23 million and $224 million, respectively, at December 31, 2015, related to floating-to-fixed energy swap contracts with unaffiliated suppliers.

Fair Value of Financial Asset69

Fair Value of Financial Assets and Liabilities - Fair Value Assets Liabilities Measured On Recurring Basis Unobservable Input Reconciliation (Details) - USD ($)		3 Months Ended					6 Months Ended		9 Months Ended
		Sep. 30, 2016		Mar. 23, 2016	Sep. 30, 2015		Sep. 30, 2016		Sep. 30, 2016		Sep. 30, 2015		Jun. 30, 2016		Mar. 24, 2016	Dec. 31, 2015		Jun. 30, 2015		Dec. 31, 2014
Fair Value, Inputs, Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		$ 1,466,000,000			$ 1,661,000,000		$ 1,466,000,000		$ 1,466,000,000		$ 1,661,000,000		$ 1,185,000,000		$ 20,000,000	$ 1,529,000,000		$ 1,536,000,000		$ 1,501,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		93,000,000			(48,000,000)				(334,000,000)		(83,000,000)
Total realized / unrealized gains (losses)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Noncurrent Payables To Affiliates		0			0				0		0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Included In Nuclear Decommissioning Payable		(1,000,000)			1,000,000				1,000,000		2,000,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Regulatory assets		(17,000,000)			(20,000,000)				21,000,000		(19,000,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		214,000,000			67,000,000				420,000,000		259,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		(7,000,000)			(18,000,000)				(11,000,000)		(42,000,000)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		288,000,000			180,000,000				248,000,000		538,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances		0							(1,000,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(28,000,000)			(13,000,000)				(119,000,000)		(75,000,000)
Purchases, sales, issuances and settlements
Purchases		214,000,000			67,000,000				420,000,000		259,000,000
Ending balance
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Change In Collateral		31,000,000			90,000,000				(51,000,000)		72,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0			69,000,000				2,000,000		84,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(4,000,000)			(3,000,000)				(11,000,000)		(38,000,000)
Fair Value, Inputs, Level 3 [Member] | Consolidation, Eliminations [Member]
Total realized / unrealized gains (losses)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Noncurrent Payables To Affiliates		(6,000,000)			0				(18,000,000)		(17,000,000)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Regulatory assets		6,000,000			0				18,000,000		17,000,000
Exelon Generation Co L L C [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings		190,000,000			229,000,000				579,000,000		623,000,000
Exelon Generation Co L L C [Member] | Interest Rate Swap [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]
Realized Investment Gains (Losses)		2,000,000			1,000,000				13,000,000		8,000,000
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		1,689,000,000			1,904,000,000		1,689,000,000		1,689,000,000		1,904,000,000		1,386,000,000			1,776,000,000		1,759,000,000		1,708,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		92,000,000			(48,000,000)				(336,000,000)		(83,000,000)
Total realized / unrealized gains (losses)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Noncurrent Payables To Affiliates		6,000,000			0				18,000,000		17,000,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Included In Nuclear Decommissioning Payable		(1,000,000)			1,000,000				1,000,000		2,000,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Regulatory assets		0			0				0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		214,000,000			67,000,000				420,000,000		259,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		(7,000,000)			(18,000,000)				(11,000,000)		(42,000,000)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		288,000,000			180,000,000				247,000,000		538,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(28,000,000)			(13,000,000)				(119,000,000)		(75,000,000)
Purchases, sales, issuances and settlements
Purchases		214,000,000			67,000,000				420,000,000		259,000,000
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Period Increase (Decrease)		25,000,000			19,000,000				10,000,000		44,000,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Change In Collateral		31,000,000			90,000,000				(51,000,000)		72,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0			69,000,000				2,000,000		84,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(4,000,000)			(3,000,000)				(11,000,000)		(38,000,000)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Nuclear Decommissioning Trust Fund Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		693,000,000			669,000,000		693,000,000		693,000,000		669,000,000		715,000,000			670,000,000		667,000,000		605,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		(4,000,000)			0				2,000,000		4,000,000
Total realized / unrealized gains (losses)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Noncurrent Payables To Affiliates		6,000,000			0				18,000,000		17,000,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Included In Nuclear Decommissioning Payable		0			0				0		0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Regulatory assets					0						0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		4,000,000			15,000,000				123,000,000		122,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		0			0				(1,000,000)		(8,000,000)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		3,000,000			(1,000,000)				7,000,000		2,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(28,000,000)			(13,000,000)				(119,000,000)		(75,000,000)
Purchases, sales, issuances and settlements
Purchases		4,000,000			15,000,000				123,000,000		122,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3					0						0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Change In Collateral		0			0				0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0			0				0		4,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0							0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Pledged Assets For Zion Station Decommissioning [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		19,000,000			29,000,000		19,000,000		19,000,000		29,000,000		25,000,000			22,000,000		41,000,000		50,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0			0				0		0
Total realized / unrealized gains (losses)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Noncurrent Payables To Affiliates		0			0				0		0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Included In Nuclear Decommissioning Payable		(1,000,000)			1,000,000				1,000,000		2,000,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Regulatory assets					0						0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0			0				1,000,000		1,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		(5,000,000)			(13,000,000)				(5,000,000)		(24,000,000)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0							0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		0			0				0		0
Purchases, sales, issuances and settlements
Purchases		0			0				1,000,000		1,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3					0						0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3					0						0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Change In Collateral		0			0				0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0							0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0							0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		935,000,000			1,174,000,000		935,000,000		935,000,000		1,174,000,000		609,000,000			1,051,000,000		1,021,000,000		1,050,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		95,000,000	[1]		(48,000,000)	[2]			(339,000,000)	[1]	(87,000,000)	[2]
Total realized / unrealized gains (losses)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Noncurrent Payables To Affiliates		0			0				0		0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Included In Nuclear Decommissioning Payable		0			0				0		0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Regulatory assets					0						0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		207,000,000	[3]		50,000,000				289,000,000	[3]	107,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		(2,000,000)			(5,000,000)				(5,000,000)		(10,000,000)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		285,000,000			181,000,000				240,000,000		536,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		0			0				0		0
Purchases, sales, issuances and settlements
Purchases		207,000,000	[3]		50,000,000				289,000,000	[3]	107,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3					(3,000,000)
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]
Indefinite-lived Intangible Assets Acquired									168,000,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Change In Collateral		31,000,000			90,000,000				(51,000,000)		72,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		(1,000,000)			69,000,000				1,000,000		80,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(4,000,000)							(11,000,000)		(38,000,000)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Other Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		42,000,000			32,000,000		42,000,000		42,000,000		32,000,000		37,000,000			33,000,000		30,000,000		3,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		1,000,000			0				1,000,000		0
Total realized / unrealized gains (losses)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Noncurrent Payables To Affiliates		0			0				0		0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Included In Nuclear Decommissioning Payable		0			0				0		0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Regulatory assets					0						0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		3,000,000			2,000,000				7,000,000		29,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		0			0				0		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0							0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		0			0				0		0
Purchases, sales, issuances and settlements
Purchases		3,000,000			2,000,000				7,000,000		29,000,000
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Change In Collateral		0			0				0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		1,000,000			0				1,000,000		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0			0				0		0
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		(244,000,000)	[4]		(243,000,000)	[5]	(244,000,000)	[4]	(244,000,000)	[4]	(243,000,000)	[5]	(221,000,000)	[4]		(247,000,000)	[4]	(223,000,000)	[5]	(207,000,000)	[5]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0	[4]		0	[5]			0	[4]	0	[5]
Total realized / unrealized gains (losses)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Noncurrent Payables To Affiliates		0	[4]		0	[5]			0	[4]	0	[5]
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Included In Nuclear Decommissioning Payable		0	[4]		0	[5]			0	[4]	0	[5]
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Regulatory assets		(23,000,000)	[4]		(20,000,000)	[5]			3,000,000	[4]	(36,000,000)	[5]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0	[4]		0	[5]			0	[4]	0	[5]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		0	[4]		0	[5]			0	[4]	0	[5]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0	[4]						0	[4]	0	[5]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		0	[4]		0	[5]			0	[4]	0	[5]
Purchases, sales, issuances and settlements
Purchases		0	[4]		0	[5]			0	[4]	0	[5]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3	[5]				0						0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3	[5]				0						0
Ending balance	[5]				(243,000,000)						(243,000,000)
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Change In Collateral		0	[4]		0	[5]			0	[4]	0	[5]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	[4]	0							0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	[4]	0							0
Pepco Holdings LLC [Member] | 6311 Life Insurance [Member] | Predecessor [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				$ 0
Pepco Holdings LLC [Member] | 6311 Life Insurance [Member] | Successor [Member]
Total realized / unrealized gains (losses)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases							(1,000,000)
Purchases, sales, issuances and settlements
Purchases							(1,000,000)
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Predecessor [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings					16,000,000
Total realized / unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)					15,000,000
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Successor [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value															20,000,000
Total realized / unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | 6311 Life Insurance [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							(2,000,000)
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | 6311 Life Insurance [Member] | Predecessor [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value				20,000,000	19,000,000						19,000,000					19,000,000		20,000,000		19,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				1,000,000	1,000,000						4,000,000
Total realized / unrealized gains (losses)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases				0	(2,000,000)						(3,000,000)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				1,000,000	0						2,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements											(1,000,000)
Purchases, sales, issuances and settlements
Purchases				0	(2,000,000)						(3,000,000)
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | 6311 Life Insurance [Member] | Successor [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		21,000,000					21,000,000		21,000,000				20,000,000		$ 20,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		1,000,000
Total realized / unrealized gains (losses)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Noncurrent Payables To Affiliates		0					0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Included In Nuclear Decommissioning Payable		0					0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Regulatory assets		0					0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0					0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		0					0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0					1,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances		0					(1,000,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		0			0		0
Purchases, sales, issuances and settlements
Purchases		0					0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3		0					0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3		0					0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Abstract]
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Change In Collateral		0					0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Preferred Stock [Member] | Predecessor [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value				0	18,000,000						18,000,000					18,000,000		3,000,000		3,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				(18,000,000)	15,000,000						15,000,000
Total realized / unrealized gains (losses)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases				0	0						0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0							15,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements				0	0						0
Purchases, sales, issuances and settlements
Purchases				$ 0	0						0
Pepco Holdings LLC [Member] | Fair Value, Inputs, Level 3 [Member] | Preferred Stock [Member] | Successor [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value					18,000,000						18,000,000
Total realized / unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)					15,000,000
Delmarva Power and Light Company [Member] | 6311 Life Insurance [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings											0
Total realized / unrealized gains (losses)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases											0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)											0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements											1,000,000
Purchases, sales, issuances and settlements
Purchases											0
Ending balance					0						0
Delmarva Power and Light Company [Member] | Fair Value, Inputs, Level 3 [Member] | 6311 Life Insurance [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value																				1,000,000
Potomac Electric Power Company [Member] | 6311 Life Insurance [Member]
Total realized / unrealized gains (losses)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0			(3,000,000)				(1,000,000)		(4,000,000)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)									2,000,000		2,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		0			0				0		0
Purchases, sales, issuances and settlements
Purchases		0			(3,000,000)				(1,000,000)		(4,000,000)
Ending balance					18,000,000						18,000,000
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		1,000,000			1,000,000
Total realized / unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0			0
Potomac Electric Power Company [Member] | Fair Value, Inputs, Level 3 [Member] | 6311 Life Insurance [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		$ 21,000,000			18,000,000		$ 21,000,000		21,000,000		18,000,000		$ 20,000,000			$ 19,000,000		$ 20,000,000		$ 18,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings					1,000,000
Total realized / unrealized gains (losses)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases									3,000,000		4,000,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)					$ 0
Purchases, sales, issuances and settlements
Purchases									$ 3,000,000		$ 4,000,000
[1]	Includes a reduction for the reclassification of $190 million and $579 million of realized gains due to the settlement of derivative contracts recorded in results of operations for the three and nine months ended September 30, 2016, respectively.
[2]	Includes a reduction for the reclassification of $229 million and $623 million of realized gains due to the settlement of derivative contracts recorded in results of operations for the three and nine months ended September 30, 2015, respectively.
[3]	Includes $168 million of fair value from contracts acquired as a result of portfolio acquisitions.
[4]	Includes $25 million of decreases in fair value and realized losses due to settlements of $2 million recorded in purchased power expense associated with floating-to-fixed energy swap contracts with unaffiliated suppliers for the three months ended September 30, 2016. Includes $10 million of decreases in fair value and realized losses due to settlements of $13 million for the nine months ended September 30, 2016.
[5]	ncludes $19 million of decreases in fair value and a reduction for realized gains due to settlements of $1 million recorded in purchased power expense associated with floating-to-fixed energy swap contracts with unaffiliated suppliers for the three months ended September 30, 2015. Includes $44 million of decreases in fair value and an increase for realized losses due to settlements of $8 million for the nine months ended September 30, 2015.

Fair Value of Financial Asset70

Fair Value of Financial Assets and Liabilities Fair Value of Financial Assets and Liabilities - Narrative (Details)	Sep. 30, 2016USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Forward Power Basis	$ 2.81
Forward Gas Basis	0.36
Middle Market Lending [Member] | Exelon Generation Co L L C [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	170,000,000
Private Equity Funds [Member] | Exelon Generation Co L L C [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	73,000,000
Real Estate Funds [Member] | Exelon Generation Co L L C [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	$ 220,000,000

Fair Value of Financial Asset71

Fair Value of Financial Assets and Liabilities - Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings (Details) - USD ($)		3 Months Ended			6 Months Ended	9 Months Ended
		Sep. 30, 2016	Mar. 23, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015
Operating Revenue [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		$ 180,000,000		$ (4,000,000)		$ (232,000,000)	$ (31,000,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		323,000,000		198,000,000		303,000,000	538,000,000
Purchased Power And Fuel [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		(85,000,000)		(44,000,000)		(107,000,000)	(56,000,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(38,000,000)		(17,000,000)		(63,000,000)	(2,000,000)
Other, net [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	[1]	(3,000,000)		0		4,000,000	4,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	[1]	3,000,000		(1,000,000)		8,000,000	2,000,000
Exelon Generation Co L L C [Member] | Operating Revenue [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		180,000,000		(4,000,000)		(232,000,000)	(31,000,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		323,000,000		198,000,000		303,000,000	538,000,000
Exelon Generation Co L L C [Member] | Purchased Power And Fuel [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		(85,000,000)		(44,000,000)		(107,000,000)	(56,000,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(38,000,000)		(17,000,000)		(63,000,000)	(2,000,000)
Exelon Generation Co L L C [Member] | Other, net [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	[1]	(4,000,000)		0		2,000,000	4,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	[1]	3,000,000		(1,000,000)		7,000,000	2,000,000
Pepco Holdings LLC [Member] | Other, net [Member] | Successor [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings					$ 2,000,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)					1,000,000
Pepco Holdings LLC [Member] | Other, net [Member] | Predecessor [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							19,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)							17,000,000
Potomac Electric Power Company [Member] | Other, net [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							4,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)							2,000,000
6311 Life Insurance [Member] | Delmarva Power and Light Company [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)							0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases							0
6311 Life Insurance [Member] | Pepco Holdings LLC [Member] | Successor [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases					(1,000,000)
6311 Life Insurance [Member] | Pepco Holdings LLC [Member] | Predecessor [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			$ 0
6311 Life Insurance [Member] | Potomac Electric Power Company [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)						2,000,000	2,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0		(3,000,000)		(1,000,000)	(4,000,000)
Fair Value, Inputs, Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		93,000,000		(48,000,000)		(334,000,000)	(83,000,000)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		288,000,000		180,000,000		248,000,000	538,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		214,000,000		67,000,000		420,000,000	259,000,000
Fair Value, Inputs, Level 3 [Member] | Exelon Generation Co L L C [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		92,000,000		(48,000,000)		(336,000,000)	(83,000,000)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		288,000,000		180,000,000		247,000,000	538,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		214,000,000		67,000,000		420,000,000	259,000,000
Fair Value, Inputs, Level 3 [Member] | Pepco Holdings LLC [Member] | Successor [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0
Fair Value, Inputs, Level 3 [Member] | Pepco Holdings LLC [Member] | Predecessor [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				16,000,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				15,000,000
Fair Value, Inputs, Level 3 [Member] | Potomac Electric Power Company [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		1,000,000		1,000,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0
Fair Value, Inputs, Level 3 [Member] | 6311 Life Insurance [Member] | Pepco Holdings LLC [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings					(2,000,000)
Fair Value, Inputs, Level 3 [Member] | 6311 Life Insurance [Member] | Pepco Holdings LLC [Member] | Successor [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		1,000,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0			1,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		$ 0			$ 0
Fair Value, Inputs, Level 3 [Member] | 6311 Life Insurance [Member] | Pepco Holdings LLC [Member] | Predecessor [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			1,000,000	1,000,000			4,000,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)			1,000,000	0			2,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases			$ 0	(2,000,000)			(3,000,000)
Fair Value, Inputs, Level 3 [Member] | 6311 Life Insurance [Member] | Potomac Electric Power Company [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				1,000,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				$ 0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases						$ 3,000,000	$ 4,000,000
[1]	Other, net activity consists of realized and unrealized gains (losses) included in income for the NDT funds held by Generation and the life insurance contracts held by Pepco.

Fair Value of Financial Asset72

Fair Value of Financial Assets and Liabilities - Fair Value Inputs Assets Quantitative Information (Details) - Fair Value, Inputs, Level 3 [Member] - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2016		Dec. 31, 2015		Dec. 31, 2014
Exelon Generation Co L L C [Member] | Derivative [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ 788,000,000	[1],[2]	$ 857,000,000	[3],[4]
Exelon Generation Co L L C [Member] | Derivative [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Forward power price assets	6		11
Forward gas price assets	1.24		1.18
Exelon Generation Co L L C [Member] | Derivative [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Forward power price assets	130		88
Forward gas price assets	$ 9.53		$ 8.95
Exelon Generation Co L L C [Member] | Derivative [Member] | Option Model Valuation Technique [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Volatility percentage	5.00%		5.00%
Exelon Generation Co L L C [Member] | Derivative [Member] | Option Model Valuation Technique [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Volatility percentage	115.00%		152.00%
Exelon Generation Co L L C [Member] | Proprietary Trading [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	$ (3,000,000)	[1],[2]	$ (7,000,000)	[3],[4]
Exelon Generation Co L L C [Member] | Proprietary Trading [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Forward power price assets	15		13
Exelon Generation Co L L C [Member] | Proprietary Trading [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Forward power price assets	68		78
Commonwealth Edison Co [Member] | Derivative [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ (244,000,000)		$ (247,000,000)
Commonwealth Edison Co [Member] | Derivative [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Forward heat rate	(8.00%)				(8.00%)
Derivatives Fair Value Footnotes [Abstract]
Fair Value Inputs, Discount for Lack of Marketability	3.00%		3.50%
Fair Value Inputs Renewable Factor	86.00%		87.00%
Commonwealth Edison Co [Member] | Derivative [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Forward heat rate	(9.00%)				(9.00%)
Derivatives Fair Value Footnotes [Abstract]
Fair Value Inputs, Discount for Lack of Marketability	8.00%		7.00%
Fair Value Inputs Renewable Factor	121.00%		128.00%
[1]	(a)The valuation techniques, unobservable inputs and ranges are the same for the asset and liability positions.
[2]	The fair values do not include cash collateral posted on level three positions of $150 million as of September 30, 2016.
[3]	The fair values do not include cash collateral posted on level three positions of $201 million as of December 31, 2015.
[4]	The valuation techniques, unobservable inputs and ranges are the same for the asset and liability positions.

Derivative Financial Instrume73

Derivative Financial Instruments - Summary of Interest Rate and Foreign Currency Hedges (Details) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Derivative [Line Items]
Interest Rate Fair Value Hedge Asset at Fair Value		$ 35
Derivative Asset, Current		754	$ 1,365
Derivative Asset, Noncurrent		669	758
Derivative Liability, Current		222	205
Derivative Liability, Noncurrent		422	374
Exelon Generation Co L L C [Member]
Derivative [Line Items]
Interest Rate Fair Value Hedge Asset at Fair Value		(4)
Derivative Asset, Current		754	1,365
Derivative Asset, Noncurrent		630	733
Derivative Liability, Current		203	182
Derivative Liability, Noncurrent		197	150
InterestRateAndForeignExchangeContract [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative Asset, Current		9	15
Derivative Asset, Noncurrent		6	14
Derivative Asset		15	29
Derivative Liability, Current		(9)	(8)
Derivative Liability, Noncurrent		(10)	(8)
Derivative Liability		(19)	(16)
Derivative, Fair Value, Net		(4)	13
InterestRateAndForeignExchangeContract [Member] | Exelon Generation Co L L C [Member] | Economic Hedges [Member]
Derivative [Line Items]
Derivative Asset, Current		15	10
Derivative Asset, Noncurrent		13	10
Derivative Asset		28	20
Derivative Liability, Current		(10)	(2)
Derivative Liability, Noncurrent		(9)	(1)
Derivative Liability		(19)	(3)
Derivative, Fair Value, Net		9	17
InterestRateAndForeignExchangeContract [Member] | Exelon Generation Co L L C [Member] | Collateral And Netting [Member]
Derivative [Line Items]
Derivative Asset, Current		(10)	(5)
Derivative Asset, Noncurrent		(11)	(1)
Derivative Asset		(21)	(6)
Derivative Liability, Current		12	11
Derivative Liability, Noncurrent		12	4
Derivative Liability		24	15
Derivative, Fair Value, Net		3	9
Interest Rate Swap [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative Liability, Current		3
Derivative [Member]
Derivative [Line Items]
Derivative Asset, Current		745	1,350
Derivative Asset, Noncurrent		624	719
Derivative Asset		1,369	2,069
Derivative Liability, Current		213	197
Derivative Liability, Noncurrent		412	366
Derivative Liability		625	563
Derivative, Fair Value, Net		744	1,506
Derivative [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative Asset, Current	[1]	745	1,350
Derivative Asset, Noncurrent	[1]	624	719
Derivative Asset	[1]	1,369	2,069
Derivative Liability, Current	[1]	194	174
Derivative Liability, Noncurrent	[1]	187	142
Derivative Liability	[1]	381	316
Derivative, Fair Value, Net	[1]	988	1,753
Not Designated as Hedging Instrument [Member] | InterestRateAndForeignExchangeContract [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative Asset, Current		4	10
Derivative Asset, Noncurrent		4	5
Derivative Asset		8	15
Derivative Liability, Current		(3)	(9)
Derivative Liability, Noncurrent		(3)	(3)
Derivative Liability		(6)	(12)
Derivative, Fair Value, Net		2	3
Designated as Hedging Instrument [Member] | InterestRateAndForeignExchangeContract [Member]
Derivative [Line Items]
Derivative Asset, Current		9	15
Derivative Asset, Noncurrent		45	39
Derivative Asset		54	54
Derivative Liability, Current		(9)	(8)
Derivative Liability, Noncurrent		(10)	(8)
Derivative Liability		(19)	(16)
Derivative, Fair Value, Net			38
Designated as Hedging Instrument [Member] | InterestRateAndForeignExchangeContract [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative Asset, Current		0	0
Derivative Asset, Noncurrent		0	0
Derivative Asset		0	0
Derivative Liability, Current		(8)	(8)
Derivative Liability, Noncurrent		(10)	(8)
Derivative Liability		(18)	(16)
Derivative, Fair Value, Net		(18)	(16)
Designated as Hedging Instrument [Member] | InterestRateAndForeignExchangeContract [Member] | Corporate, Non-Segment [Member]
Derivative [Line Items]
Derivative Asset, Current		0	0
Derivative Asset, Noncurrent		39	25
Derivative Asset		39	25
Derivative Liability, Current		0	0
Derivative Liability, Noncurrent		0	0
Derivative Liability		0	0
Derivative, Fair Value, Net		$ 39	$ 25
[1]	.

Derivative Financial Instrume74

Derivative Financial Instruments - Summary of Gains and Losses on Hedges (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2016	Jun. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Derivative [Line Items]
Income taxes		$ 340		$ 115	$ 625	$ 805
Gain (Loss) on Cash Flow Hedge Ineffectiveness, Net	[1]	6			12
Derivative, Loss on Derivative			$ 3
Increase (Decrease) in Fair Value of Hedged Item in Price Risk Fair Value Hedge				(13)		(4)
Gain (Loss) on Fair Value Hedges Recognized in Earnings				16		15
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value		(10)			(10)		$ (8)
Exelon Generation Co L L C [Member]
Derivative [Line Items]
Income taxes		173		$ (36)	293	371
Increase (Decrease) in Fair Value of Hedged Item in Price Risk Fair Value Hedge	[1]				0	0
Interest Expense [Member] | Fair Value Hedging [Member]
Derivative [Line Items]
Increase (Decrease) in Fair Value of Hedged Item in Price Risk Fair Value Hedge		14			(3)
Interest Rate Swap [Member] | Fair Value Hedging [Member]
Derivative [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings		$ (8)			15
Interest Rate Swap [Member] | Fair Value Hedging [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	[1]				$ 0	(1)
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Interest Expense [Member] | Fair Value Hedging [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative, Loss on Derivative						$ (1)
[1]	For the nine months ended September 30, 2015, the loss on Generation swaps included $1 million realized in earnings with an immaterial amount excluded from hedge effectiveness testing.

Derivative Financial Instrume75

Derivative Financial Instruments Derivative Financial Instruments - Summary of Derivative Fair Value Balances (Details) - USD ($) $ in Millions		Sep. 30, 2016	Mar. 23, 2016	Dec. 31, 2015
Derivative [Line Items]
Derivative Asset, Current		$ 754		$ 1,365
Derivative Asset, Noncurrent		669		758
Derivative Liability, Current		(222)		(205)
Derivative Liability, Noncurrent		(422)		(374)
Derivative [Member]
Derivative [Line Items]
Derivative Asset, Current		745		1,350
Derivative Asset, Noncurrent		624		719
Total mark-to-market derivative net assets (liabilities)		744		1,506
Total mark-to-market derivative assets		1,369		2,069
Derivative Liability, Current		(213)		(197)
Derivative Liability, Noncurrent		(412)		(366)
Total mark-to-market derivative liabilities		(625)		(563)
Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative Asset, Current		754		1,365
Derivative Asset, Noncurrent		630		733
Derivative Liability, Current		(203)		(182)
Derivative Liability, Noncurrent		(197)		(150)
Exelon Generation Co L L C [Member] | Economic Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Current		3,482		5,236
Derivative Asset, Noncurrent		2,139		1,860
Total mark-to-market derivative net assets (liabilities)		507		516
Total mark-to-market derivative assets		5,621		7,096
Derivative Liability, Current		(3,229)		(4,907)
Derivative Liability, Noncurrent		(1,885)		(1,673)
Total mark-to-market derivative liabilities		(5,114)		(6,580)
Exelon Generation Co L L C [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Current assets collateral offset		135		352
Noncurrent assets collateral offset		84		180
Current liabilities collateral offset		156		480
Noncurrent liabilities collateral offset		110		222
Total cash collateral received net of cash collateral posted		485		(1,234)
Exelon Generation Co L L C [Member] | Derivative [Member]
Derivative [Line Items]
Derivative Asset, Current	[1]	745		1,350
Derivative Asset, Noncurrent	[1]	624		719
Total mark-to-market derivative net assets (liabilities)	[1]	988		1,753
Total mark-to-market derivative assets	[1]	1,369		2,069
Derivative Liability, Current	[1]	(194)		(174)
Derivative Liability, Noncurrent	[1]	(187)		(142)
Total mark-to-market derivative liabilities	[1]	(381)		(316)
Exelon Generation Co L L C [Member] | Proprietary Trading [Member]
Derivative [Line Items]
Derivative Asset, Current		67		108
Derivative Asset, Noncurrent		31		22
Total mark-to-market derivative net assets (liabilities)		(4)		3
Total mark-to-market derivative assets		98		130
Derivative Liability, Current		(61)		(94)
Derivative Liability, Noncurrent		(41)		(33)
Total mark-to-market derivative liabilities		(102)		(127)
Exelon Generation Co L L C [Member] | Collateral And Netting [Member]
Derivative [Line Items]
Derivative Asset, Current		(2,804)		(3,994)
Derivative Asset, Noncurrent		(1,546)		(1,163)
Total mark-to-market derivative net assets (liabilities)	[2]	485		1,234
Total mark-to-market derivative assets	[2]	(4,350)		(5,157)
Derivative Liability, Current		3,096		4,827
Derivative Liability, Noncurrent		1,739		1,564
Total mark-to-market derivative liabilities	[2]	4,835		6,391
Commonwealth Edison Co [Member]
Derivative [Line Items]
Derivative Liability, Current		(19)		(23)
Derivative Liability, Noncurrent		(225)		(224)
Commonwealth Edison Co [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Current		0		0
Derivative Asset, Noncurrent		0		0
Total mark-to-market derivative net assets (liabilities)	[3]	(244)		(247)
Total mark-to-market derivative assets	[3]	0		0
Derivative Liability, Current		19		(23)
Derivative Liability, Noncurrent		225		(224)
Total mark-to-market derivative liabilities	[3]	(244)		(247)
Delmarva Power and Light Company [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Current		1		0
Derivative Asset, Noncurrent		0		0
Total mark-to-market derivative net assets (liabilities)		1		(2)
Total mark-to-market derivative assets		1		0
Derivative Liability, Current		0		2
Derivative Liability, Noncurrent		0		0
Total mark-to-market derivative liabilities		0		2
Delmarva Power and Light Company [Member] | Derivative [Member]
Derivative [Line Items]
Derivative Asset, Current	[4]	0		0
Derivative Asset, Noncurrent	[4]	0		0
Total mark-to-market derivative net assets (liabilities)		0		0
Total mark-to-market derivative assets	[4]	0		0
Derivative Liability, Current	[4]	0		0
Derivative Liability, Noncurrent	[4]	0		0
Total mark-to-market derivative liabilities	[4]	0		0
Delmarva Power and Light Company [Member] | Collateral And Netting [Member]
Derivative [Line Items]
Derivative Asset, Current		(1)		0
Derivative Asset, Noncurrent		0		0
Total mark-to-market derivative net assets (liabilities)		(1)		2
Total mark-to-market derivative assets		(1)		0
Derivative Liability, Current		0		(2)
Derivative Liability, Noncurrent		0		0
Total mark-to-market derivative liabilities		0		(2)
Pepco Holdings LLC [Member]
Derivative [Line Items]
Total mark-to-market derivative net assets (liabilities)			$ 0
Pepco Holdings LLC [Member] | Successor [Member]
Derivative [Line Items]
Derivative Asset, Current		0
Derivative Asset, Noncurrent		0
Total mark-to-market derivative net assets (liabilities)		0
Total mark-to-market derivative assets		0
Derivative Liability, Current		0
Derivative Liability, Noncurrent		0
Total mark-to-market derivative liabilities		$ 0
Pepco Holdings LLC [Member] | Predecessor [Member]
Derivative [Line Items]
Derivative Asset, Current				18
Derivative Asset, Noncurrent				0
Total mark-to-market derivative net assets (liabilities)				18
Total mark-to-market derivative assets				18
Derivative Liability, Current				0
Derivative Liability, Noncurrent				0
Total mark-to-market derivative liabilities				0
Pepco Holdings LLC [Member] | Derivative [Member] | Corporate, Non-Segment [Member]
Derivative [Line Items]
Derivative Asset, Current				18
Derivative Asset, Noncurrent				0
Total mark-to-market derivative net assets (liabilities)				18
Total mark-to-market derivative assets				18
Derivative Liability, Current				0
Derivative Liability, Noncurrent				0
Total mark-to-market derivative liabilities				$ 0
[1]	.
[2]	.
[3]	.
[4]	Current and noncurrent assets are shown net of collateral of $352 million and $180 million, respectively, and current and noncurrent liabilities are shown net of collateral of $480 million and $222 million, respectively. The total cash collateral posted, net of cash collateral received and offset against mark-to-market assets and liabilities was $1,234 million at December 31, 2015.

Derivative Financial Instrume76

Derivative Financial Instruments - Summary of AOCI related to Cash Flow Hedges (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2016		Sep. 30, 2015		Sep. 30, 2016		Sep. 30, 2015		Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Derivative [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	$ (2,523)		$ (2,596)		$ (2,523)		$ (2,596)			$ (2,624)		$ (2,684)
OCI before reclassifications	[1]					(5)		(64)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1],[2]					(106)		(152)
Income taxes		340		115		625		805
Effect of Hedges on Accumulated Other Comprehensive Income [Roll Forward]
Reclassifications from accumulated OCI to net income		4,535		4,564		12,243		14,278
Exelon Generation Co L L C [Member]
Derivative [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	(56)		(60)		(56)		(60)			(63)		(36)
OCI before reclassifications	[1]					5		(30)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1],[2]					(2)		(6)
Income taxes		173		(36)		293		371
Effect of Hedges on Accumulated Other Comprehensive Income [Roll Forward]
Reclassifications from accumulated OCI to net income		4,533		4,562		12,234		14,270
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Derivative [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	(23)		(24)		(23)		(24)			(19)		(28)
OCI before reclassifications	[1]					(1)		(18)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1],[2]					3		(22)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(23)	[1]	(24)	[1]	(23)	[1]	(24)	[1]	$ (26)		$ (19)	(28)
OCI before reclassifications				(8)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(24)	[1]	(25)	[1]	(24)	[1]	(25)	[1]		$ (21)		(18)
OCI before reclassifications	[1]					0		(13)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1],[2]					3		(6)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Exelon Generation Co L L C [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(24)	[1]	(25)	[1]	(24)	[1]	(25)	[1]				$ (18)
OCI before reclassifications				(7)
Energy Related Hedges [Member] | Exelon Generation Co L L C [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(24)	[1]	(25)	[1]	(24)	[1]	(25)	[1]	$ (25)		$ (21)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Derivative [Line Items]
Income taxes	[3]	0				0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Income taxes	[3]	0				0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Derivative [Line Items]
Income taxes	[3]			(1)		2		(13)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Income taxes				(1)	[3]	$ 2	[3]	3
Interest Expense [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Cash Flow Hedging [Member]
Effect of Hedges on Accumulated Other Comprehensive Income [Roll Forward]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion		3		3				8
Interest Expense [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Exelon Generation Co L L C [Member] | Cash Flow Hedging [Member]
Effect of Hedges on Accumulated Other Comprehensive Income [Roll Forward]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion		$ 1		$ 3				8
Interest Expense [Member] | Operating Revenue [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Cash Flow Hedging [Member]
Effect of Hedges on Accumulated Other Comprehensive Income [Roll Forward]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion								(18)
Interest Expense [Member] | Total Cash Flow Hedges [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Exelon Generation Co L L C [Member] | Cash Flow Hedging [Member]
Effect of Hedges on Accumulated Other Comprehensive Income [Roll Forward]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion								(13)
Operating Revenue [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Cash Flow Hedging [Member]
Effect of Hedges on Accumulated Other Comprehensive Income [Roll Forward]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion								(2)
Operating Revenue [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Exelon Generation Co L L C [Member] | Cash Flow Hedging [Member]
Effect of Hedges on Accumulated Other Comprehensive Income [Roll Forward]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion								(2)
Operating Revenue [Member] | Total Cash Flow Hedges [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Exelon Generation Co L L C [Member] | Cash Flow Hedging [Member]
Effect of Hedges on Accumulated Other Comprehensive Income [Roll Forward]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion								0
Operating Revenue [Member] | Total Cash Flow Hedges [Member] | Operating Revenue One [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Cash Flow Hedging [Member]
Effect of Hedges on Accumulated Other Comprehensive Income [Roll Forward]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion								$ 16
[1]	All amounts are net of tax and noncontrolling interest. Amounts in parenthesis represent a decrease in AOCI.
[2]	See next tables for details about these reclassifications.
[3]	Amounts in parenthesis represent a decrease in net income.

Derivative Financial Instrume77

Derivative Financial Instruments - Summary of Economic Hedges (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivative [Line Items]
Unrealized Gain (Loss) on Commodity Contracts	$ 207	$ (42)	$ 163	$ 350
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(118)	(97)	(267)	(98)
Unrealized Gain (Loss) on Derivatives			(100)	363
Change in Unrealized Gain (Loss) on Hedged Item in Foreign Currency Fair Value Hedge	1	2	(3)	48
Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Commodity Contracts	207	(42)	163	350
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(118)	(97)	(267)	(98)
Unrealized Gain (Loss) on Derivatives			(112)	252
Change in Unrealized Gain (Loss) on Hedged Item in Foreign Currency Fair Value Hedge	1	2	(3)	12
Purchased Power And Fuel [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Commodity Contracts	(73)	(178)	36	(163)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(26)	46	217	249
Change in Unrealized Gain (Loss) on Hedged Item in Foreign Currency Fair Value Hedge	0	0	0	0
Interest Expense [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Commodity Contracts				0
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net				0
Change in Unrealized Gain (Loss) on Hedged Item in Foreign Currency Fair Value Hedge		0		36
Interest Expense [Member] | Corporate, Non-Segment [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net
Change in fair value		0
Operating Revenue [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Commodity Contracts	280	136	127	513
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(92)	(143)	(484)	(347)
Change in Unrealized Gain (Loss) on Hedged Item in Foreign Currency Fair Value Hedge	1	2	(3)	12
Operating Revenue [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	(1)	(6)	1	(5)
Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(2)	(2)	(6)	58
Unrealized Gain (Loss) on Derivatives	(1)	0	(9)	106
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	88	(139)	(113)	358
Foreign Exchange Contract [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(2)	(2)	(6)	(6)
Unrealized Gain (Loss) on Derivatives	(1)	0	(9)	6
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	88	(139)	(113)	258
Foreign Exchange Contract [Member] | Purchased Power And Fuel [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	0	0	0
Unrealized Gain (Loss) on Derivatives	0	0	0	0
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	(99)	(132)	253	86
Foreign Exchange Contract [Member] | Interest Expense [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		0		64
Unrealized Gain (Loss) on Derivatives		0		100
Unrealized Gain (Loss) on Derivatives and Commodity Contracts		0		100
Foreign Exchange Contract [Member] | Operating Revenue [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(2)	(2)	(6)	(6)
Unrealized Gain (Loss) on Derivatives	(1)	0	(9)	6
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	187	(7)	(366)	172
Foreign Exchange Contract [Member] | Operating Revenue [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	1	(3)	2	(9)
Unrealized Gain (Loss) on Derivatives	1	0	0	(2)
Change in Unrealized Gain (Loss) on Hedged Item in Foreign Currency Fair Value Hedge	0	3	(2)	7
Commodity Contract [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	89	(139)	(104)	252
Commodity Contract [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	89	(139)	(104)	252
Commodity Contract [Member] | Purchased Power And Fuel [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	(99)	(132)	253	86
Commodity Contract [Member] | Interest Expense [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives		0		0
Commodity Contract [Member] | Operating Revenue [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	188	(7)	(357)	166
Commodity Contract [Member] | Operating Revenue [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Commodity Contracts	4	(4)	18	5
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(6)	(2)	(17)	(8)
Unrealized Gain (Loss) on Derivatives	$ (2)	$ (6)	$ 1	$ (3)

Derivative Financial Instrume78

Derivative Financial Instruments - Summary of Proprietary Trading Activities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivative [Line Items]
Unrealized Gain (Loss) on Commodity Contracts	$ 207	$ (42)	$ 163	$ 350
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(118)	(97)	(267)	(98)
Unrealized Gain (Loss) on Derivatives			(100)	363
Change in Unrealized Gain (Loss) on Hedged Item in Foreign Currency Fair Value Hedge	1	2	(3)	48
Operating Revenue [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	(1)	(6)	1	(5)
Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Commodity Contracts	207	(42)	163	350
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(118)	(97)	(267)	(98)
Unrealized Gain (Loss) on Derivatives			(112)	252
Change in Unrealized Gain (Loss) on Hedged Item in Foreign Currency Fair Value Hedge	1	2	(3)	12
Commodity Contract [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	89	(139)	(104)	252
Commodity Contract [Member] | Operating Revenue [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Commodity Contracts	4	(4)	18	5
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(6)	(2)	(17)	(8)
Unrealized Gain (Loss) on Derivatives	(2)	(6)	1	(3)
Commodity Contract [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	89	(139)	(104)	252
Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(2)	(2)	(6)	58
Unrealized Gain (Loss) on Derivatives	(1)	0	(9)	106
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	88	(139)	(113)	358
Foreign Exchange Contract [Member] | Operating Revenue [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	1	(3)	2	(9)
Unrealized Gain (Loss) on Derivatives	1	0	0	(2)
Change in Unrealized Gain (Loss) on Hedged Item in Foreign Currency Fair Value Hedge	0	3	(2)	7
Foreign Exchange Contract [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(2)	(2)	(6)	(6)
Unrealized Gain (Loss) on Derivatives	(1)	0	(9)	6
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	$ 88	$ (139)	$ (113)	$ 258

Derivative Financial Instrume79

Derivative Financial Instruments - Summary of Credit Risk Exposure (Details) - Exelon Generation Co L L C [Member] $ in Millions	Sep. 30, 2016USD ($)
Derivative [Line Items]
Investor-owned utilities, marketers and power producers	$ 757
Energy Cooperatives And Municipalities	712
Financial institutions	117
Other	58
Net Exposure [Member]
Derivative [Line Items]
Investment grade	1,013
Non-investment grade	153
No external ratings - internally rated - investment grade	420
No external ratings - internally rated - non-investment grade	58
Total	1,644
Total Exposure Before Credit Collateral [Member]
Derivative [Line Items]
Investment grade	1,017
Non-investment grade	175
No external ratings - internally rated - investment grade	423
No external ratings - internally rated - non-investment grade	61
Total	1,676
Credit Collateral [Member]
Derivative [Line Items]
Investment grade	4
Non-investment grade	22
No external ratings - internally rated - investment grade	3
No external ratings - internally rated - non-investment grade	3
Total	32	[1]
Number Of Counterparties Greater Than Ten Percent Of Net Exposure [Member]
Derivative [Line Items]
Investment grade	1
Non-investment grade	0
No external ratings - internally rated - investment grade	0
No external ratings - internally rated - non-investment grade	0
Total	1
Net Exposure Of Counterparties Greater Than Ten Percent Of Net Exposure [Member]
Derivative [Line Items]
Investment grade	355
Non-investment grade	0
No external ratings - internally rated - investment grade	0
No external ratings - internally rated - non-investment grade	0
Total	$ 355
[1]	of September 30, 2016, credit collateral held from counterparties where Generation had credit exposure included $10 million of cash and $22 million of letters of credit. The credit collateral does not include non-liquid collateral.

Derivative Financial Instrume80

Derivative Financial Instruments - Summary of Credit Risk Related Contingent Features (Details) - Exelon Generation Co L L C [Member] - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Derivative [Line Items]
Aggregate fair value of derivatives with credit-risk-related contingent features		$ (975)	$ (932)
Contractual right of offset related to derivative assets		664	684
Net liability position after contractual right of offset	[1]	$ (311)	$ (248)
[1]	unt represents the net fair value of out-of-the-money derivative contracts containing credit-risk related contingent features after considering the mitigating effects of offsetting positions under master netting arrangements and reflects the actual net liability upon which any potential contingent collateral obligations would be based.Ge

Derivative Financial Instrume81

Derivative Financial Instruments - Narrative (Details) $ in Millions		3 Months Ended					9 Months Ended			12 Months Ended
		Sep. 30, 2016USD ($)GWh	Jun. 30, 2016USD ($)	Sep. 30, 2015USD ($)GWh		Jun. 30, 2015USD ($)	Sep. 30, 2016USD ($)GWh		Sep. 30, 2015USD ($)GWh	Dec. 31, 2015USD ($)	Mar. 31, 2016USD ($)
Derivative [Line Items]
Income taxes		$ 340		$ 115			$ 625		$ 805
Derivative, Notional Amount			$ 100								$ 600
Derivative, Loss on Derivative			3
Derivative Instruments, Loss Recognized in Other Comprehensive Income (Loss), Effective Portion			$ 3
Hypothetical increase in interest rates associated with variable-rate debt							5
Ineffective portion recognized in income	[1]	6					12
Mark-to-market derivative liabilities (noncurrent liabilities)		422					422			$ 374
Derivative Liability, Current		222					222			205
Cash collateral posted		10					10
Letters of credit posted		22					22
Interest Rate Fair Value Hedge Asset at Fair Value		35					35
Debt Instrument, Face Amount				750					750
Exelon Generation Co L L C [Member]
Derivative [Line Items]
Income taxes		173		$ (36)			293		$ 371
Mark-to-market derivative liabilities (noncurrent liabilities)		197					197			150
Derivative Liability, Current		203					203			182
Cash collateral received not offset against net derivative positions		(5)					(5)			3
Cash collateral posted		501					501			1,267
Letters of credit held		22					22			78
Letters of credit posted		420					420			497
Cash collateral held		18					18			21
Incremental collateral for loss of investment grade credit rating		1,900					1,900			2,000
Interest Rate Fair Value Hedge Asset at Fair Value		$ (4)					$ (4)
Derivative, Nonmonetary Notional Amount, Energy Measure | GWh		1,506		1,913			4,015		5,378
Commonwealth Edison Company [Member]
Derivative [Line Items]
Cash collateral held		$ 3					$ 3
Commonwealth Edison Co [Member]
Derivative [Line Items]
Income taxes		75		$ 99			244		$ 226
Mark-to-market derivative liabilities (noncurrent liabilities)		225					225			224
Derivative Liability, Current		19					19			23
Cash collateral held		19					19
Incremental collateral for loss of investment grade credit rating		17					17
Credit Exposure Under Off System Sales		1					1
PECO Energy Co [Member]
Derivative [Line Items]
Income taxes		54		37			$ 121		122
Estimated percentage of natural gas purchases hedged							25.00%
Incremental collateral for loss of investment grade credit rating		25					$ 25
Baltimore Gas and Electric Company [Member]
Derivative [Line Items]
Income taxes		36		35			109		141
Incremental collateral for loss of investment grade credit rating		29					29
Credit Exposure Under Off System Sales		1					1
Delmarva Power and Light Company [Member]
Derivative [Line Items]
Income taxes		19		9			18		34
Incremental collateral for loss of investment grade credit rating		9					$ 9
Minimum [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Expected Generation Hedged In Next Twelve Months							98.00%
Expected Generation Hedged In Year Two							85.00%
Expected generation hedged in year three							54.00%
Minimum [Member] | Baltimore Gas and Electric Company [Member]
Derivative [Line Items]
Estimated percentage of natural gas purchases hedged							10.00%
Maximum [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Expected Generation Hedged In Next Twelve Months							101.00%
Expected Generation Hedged In Year Two							88.00%
Expected generation hedged in year three							57.00%
Maximum [Member] | Baltimore Gas and Electric Company [Member]
Derivative [Line Items]
Estimated percentage of natural gas purchases hedged							20.00%
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount		800					$ 800
Interest Rate Swap [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative Liability, Current		3					3
Cash Flow Hedging [Member]
Derivative [Line Items]
Derivative, Notional Amount											$ 100
Designated as Hedging Instrument [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Notional Amount of Pre-issuance Interest Rate Cash Flow Hedge Derivatives		672					672
Designated as Hedging Instrument [Member] | Commonwealth Edison Co [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	[2]	(244)					(244)			(247)
Mark-to-market derivative liabilities (noncurrent liabilities)		(225)					(225)			224
Derivative Liability, Current		(19)					(19)			23
Designated as Hedging Instrument [Member] | Delmarva Power and Light Company [Member]
Derivative [Line Items]
Derivative, Fair Value, Net		1					1			(2)
Mark-to-market derivative liabilities (noncurrent liabilities)		0					0			0
Derivative Liability, Current		0					0			(2)
Foreign Exchange Contract [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative, Notional Amount		85					85
Energy Related Derivative [Member] | Delmarva Power and Light Company [Member]
Derivative [Line Items]
Brokered Natural Gas Margin Revenue							3
Derivative [Member]
Derivative [Line Items]
Derivative, Fair Value, Net		744					744			1,506
Mark-to-market derivative liabilities (noncurrent liabilities)		412					412			366
Derivative Liability, Current		213					213			197
Derivative [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	[3]	988					988			1,753
Mark-to-market derivative liabilities (noncurrent liabilities)	[3]	187					187			142
Derivative Liability, Current	[3]	194					194			174
Derivative [Member] | Delmarva Power and Light Company [Member]
Derivative [Line Items]
Derivative, Fair Value, Net		0					0			0
Mark-to-market derivative liabilities (noncurrent liabilities)	[4]	0					0			0
Derivative Liability, Current	[4]	0					0			0
Fair Value Hedging [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount		800					800			800
Increase (Decrease) in Fair Value of Interest Rate Fair Value Hedging Instruments							39			$ 25
Cash Flow Hedging [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount		90					90
Cash Flow Hedging [Member] | Interest Rate Contract [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Increase In Notional Amount Of Derivative Instruments							176
Other Solar Projects [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Notional amounts on forward starting interest rate swaps		25					25
Other Solar Projects [Member] | Designated as Hedging Instrument [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Notional amounts on forward starting interest rate swaps		24					24
PHI Merger [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount						$ 2,400
PHI Merger [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net						$ 64
ExGen Texas Power [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount		496					496
ExGen Texas Power [Member] | Cash Flow Hedging [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Mark-to-market derivative liabilities (noncurrent liabilities)		15					15
Reclassification out of Accumulated Other Comprehensive Income [Member]
Derivative [Line Items]
Income taxes	[5]	0					0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Income taxes	[5]	0					0
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Derivative [Line Items]
Income taxes	[5]			(1)			2		(13)
Cash Flow Hedge Gain Loss Reclassified To Pretax Net Income From Accumulated Other Comprehensive Income									2
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Income taxes				$ (1)	[5]		2	[5]	3
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Income taxes	[5]						(2)		$ (10)
Commonwealth Edison Co Affiliate [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Net receivable from electric utility		24					24
PECO Energy Co Affiliate [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Net receivable from affiliated electric and gas utility		45					45
Baltimore Gas And Electric Company Affiliate [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Net receivable from affiliated electric and gas utility		22					22
Potomac Electric Power Company [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Net receivable from electric utility		47					47
Delmarva Power and Light Company [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Net receivable from electric utility		12					12
Atlantic City Electric Company [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Net receivable from electric utility		$ 10					$ 10
[1]	For the nine months ended September 30, 2015, the loss on Generation swaps included $1 million realized in earnings with an immaterial amount excluded from hedge effectiveness testing.
[2]	.
[3]	.
[4]	Current and noncurrent assets are shown net of collateral of $352 million and $180 million, respectively, and current and noncurrent liabilities are shown net of collateral of $480 million and $222 million, respectively. The total cash collateral posted, net of cash collateral received and offset against mark-to-market assets and liabilities was $1,234 million at December 31, 2015.
[5]	Amounts in parenthesis represent a decrease in net income.

Debt and Credit Agreements - Co

Debt and Credit Agreements - Commercial Paper Borrowings Outstanding (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Commonwealth Edison Co [Member]
Short-term Debt [Line Items]
Commercial paper borrowings	$ 10	$ 294
Baltimore Gas and Electric Company [Member]
Short-term Debt [Line Items]
Commercial paper borrowings	0	210
PEPCO Holdings Inc [Member]
Short-term Debt [Line Items]
Commercial paper borrowings	0	484
Potomac Electric Power Company [Member]
Short-term Debt [Line Items]
Commercial paper borrowings	0	64
Delmarva Power and Light Company [Member]
Short-term Debt [Line Items]
Commercial paper borrowings	17	105
Atlantic City Electric Company [Member]
Short-term Debt [Line Items]
Commercial paper borrowings	$ 0	$ 5

Debt and Credit Agreements - Na

Debt and Credit Agreements - Narrative (Details) - USD ($) $ in Millions	Feb. 29, 2016	Sep. 30, 2016	Apr. 01, 2016	Mar. 31, 2016	Jan. 13, 2016	Dec. 31, 2015	Sep. 30, 2015
Debt Instrument [Line Items]
Interest Rate		4.10%
Debt Instrument, Face Amount							$ 750
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity		$ 600	$ 100
Revolving Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity		$ 500
Exelon Generation Co L L C [Member] | NonrecourseDebtSeptember2019Member [Member]
Debt Instrument [Line Items]
Interest Rate		4.80%
Debt Instrument, Face Amount		$ 4
Exelon Generation Co L L C [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			$ 200	$ 150
Pepco Holdings LLC [Member]
Debt Instrument [Line Items]
Short-term Bank Loans and Notes Payable					$ 500		$ 300
Short-term Debt, Percentage Bearing Variable Interest Rate					1.00%
Pepco Holdings LLC [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity		900
Pepco Holdings LLC [Member] | Revolving Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		1,500
Delmarva Power and Light Company [Member] | Variable Rate Demand Obligation [Member]
Debt Instrument [Line Items]
Long-term Debt, Current Maturities		105
CEU Holdings, LLC [Member]
Debt Instrument [Line Items]
Repayments of Bank Debt		7
Line of Credit Facility, Increase (Decrease), Other, Net	$ 45
Secured Demand Note Deficiency	$ 23	16
Outstanding borrowings/facility draws						$ 85
Line of Credit Facility, Maximum Borrowing Capacity		$ 500
Long-term Debt				$ 61		$ 68

Debt and Credit Agreements - Sc

Debt and Credit Agreements - Schedule of Issuance of Long-Term Debt (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Debt Instrument [Line Items]
Interest Rate	4.10%
Debt Instrument, Face Amount		$ 750
Proceeds from (Repayments of) Other Long-term Debt	$ (30)	0
SeniorUnsecured245April2021 [Member]
Debt Instrument [Line Items]
Interest Rate	2.45%
Debt Instrument, Face Amount	$ 300
SeniorUnsecured340April2026 [Member]
Debt Instrument [Line Items]
Interest Rate	3.40%
Debt Instrument, Face Amount	$ 750
SeniorUnsecured445April2046 [Member]
Debt Instrument [Line Items]
Interest Rate	4.45%
Debt Instrument, Face Amount	$ 750
Exelon Generation Co L L C [Member] | Energy Efficiency Project Financing [Member]
Debt Instrument [Line Items]
Interest Rate	1.43%
Debt Instrument, Face Amount	$ 86
Exelon Generation Co L L C [Member] | EscoNotes390February2018 [Member]
Debt Instrument [Line Items]
Interest Rate	3.40%
Debt Instrument, Face Amount	$ 13
Exelon Generation Co L L C [Member] | DominionFederal [Member]
Debt Instrument [Line Items]
Interest Rate	0.00%
Debt Instrument, Face Amount	$ 16
Exelon Generation Co L L C [Member] | NonrecourseDebtSeptember2036 [Member]
Debt Instrument [Line Items]
Interest Rate	3.90%
Debt Instrument, Face Amount	$ 150
Exelon Generation Co L L C [Member] | NonrecourseDebtSeptember2019Member [Member]
Debt Instrument [Line Items]
Interest Rate	4.80%
Debt Instrument, Face Amount	$ 4
Exelon Generation Co L L C [Member] | DOE Financing Project [Member] | Energy Efficiency Project Financing [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 150
Commonwealth Edison Co [Member] | FirstMortgageBonds120 [Member]
Debt Instrument [Line Items]
Interest Rate	2.55%
Debt Instrument, Face Amount	$ 500
Commonwealth Edison Co [Member] | FirstMortgageBonds121 [Member]
Debt Instrument [Line Items]
Interest Rate	3.65%
Debt Instrument, Face Amount	$ 700
PECO Energy Co [Member]
Debt Instrument [Line Items]
Proceeds from (Repayments of) Other Long-term Debt	$ (30)	$ 0
PECO Energy Co [Member] | FirstMortgageBondsSeptember2021 [Member]
Debt Instrument [Line Items]
Interest Rate	1.70%
Debt Instrument, Face Amount	$ 0
Potomac Electric Power Company [Member] | EscoNotes330August2017 [Member]
Debt Instrument [Line Items]
Interest Rate	3.50%
Debt Instrument, Face Amount	$ 11
Potomac Electric Power Company [Member] | ESCONotesDOEGDecember2017 [Member]
Debt Instrument [Line Items]
Interest Rate	3.30%
Debt Instrument, Face Amount	$ 2
Baltimore Gas and Electric Company [Member]
Debt Instrument [Line Items]
Proceeds from (Repayments of) Other Long-term Debt	(190)
Baltimore Gas and Electric Company [Member] | SeniorNotesAugust2046 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	500
Baltimore Gas and Electric Company [Member] | SeniorNotesAugust2026Member [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 350
Baltimore Gas and Electric Company [Member] | Notes Payable, Other Payables [Member] | SeniorNotesAugust2046 [Member]
Debt Instrument [Line Items]
Interest Rate	3.50%
Baltimore Gas and Electric Company [Member] | Notes Payable, Other Payables [Member] | SeniorNotesAugust2026Member [Member]
Debt Instrument [Line Items]
Interest Rate	2.40%

Income Taxes - Reconciliation t

Income Taxes - Reconciliation to Effective Tax Rate (Details)	3 Months Ended			6 Months Ended	9 Months Ended
	Sep. 30, 2016	Mar. 23, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015
Increase (decrease) due to:
U.S. Federal statutory rate	35.00%		35.00%		35.00%	35.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent	3.80%		2.70%		2.50%	3.10%
Effective Income Tax Rate Reconciliation, Tax Contingency, Other, Percent	(4.00%)		(5.40%)		(4.80%)	(0.90%)
Domestic production activities deduction	(0.00%)		(4.90%)		(0.00%)	(2.80%)
Effective Income Tax Rate Reconciliation, Deduction, Medicare Prescription Drug Benefit, Percent	0.00%		0.00%		0.00%	0.00%
Amortization of investment tax credit, including deferred taxes on basis difference	(0.90%)		(2.30%)		(1.30%)	(1.20%)
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent	(3.00%)		(1.40%)		(4.50%)	1.20%
Production tax credits and other credits	(0.60%)				(6.20%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(2.90%)		(3.80%)		(4.10%)	(2.20%)
Noncontrolling interests	0.20%		1.70%		0.50%	0.00%
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent	(0.10%)		(6.40%)		(0.50%)	(1.60%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Other, Percent	4.30%				2.30%
Other(c)	0.80%		(1.20%)		(1.80%)	(0.90%)
Effective income tax rate	39.00%		16.40%		39.10%	29.10%
Predecessor [Member]
Increase (decrease) due to:
Domestic production activities deduction			(0.00%)
Noncontrolling interests			0.00%
Successor [Member]
Increase (decrease) due to:
Effective Income Tax Rate Reconciliation, Deduction, Medicare Prescription Drug Benefit, Percent		0.00%		0.00%
Exelon Generation Co L L C [Member]
Increase (decrease) due to:
U.S. Federal statutory rate	35.00%		35.00%		35.00%	35.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent	2.60%		2.10%		2.60%	2.80%
Effective Income Tax Rate Reconciliation, Tax Contingency, Other, Percent	(7.80%)		(12.50%)		(8.80%)	(1.60%)
Domestic production activities deduction	(0.00%)		(11.60%)		(0.00%)	(4.90%)
Effective Income Tax Rate Reconciliation, Deduction, Medicare Prescription Drug Benefit, Percent	0.00%		0.00%		0.00%	0.00%
Amortization of investment tax credit, including deferred taxes on basis difference	(1.60%)		(5.20%)		(2.00%)	(1.90%)
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent	(0.00%)		(0.00%)		(0.00%)	(0.00%)
Production tax credits and other credits	(0.00%)				(0.00%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(5.70%)		(9.00%)		(7.60%)	(3.80%)
Noncontrolling interests	0.50%		3.90%		0.90%	0.10%
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent	(0.30%)		(15.20%)		1.70%	(2.90%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Other, Percent	0.00%				0.00%
Other(c)	0.50%		(0.40%)		2.10%	(0.60%)
Effective income tax rate	38.40%		(12.10%)		33.90%	23.40%
Commonwealth Edison Co [Member]
Increase (decrease) due to:
U.S. Federal statutory rate	35.00%		35.00%		35.00%	35.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent	7.30%		5.00%		5.40%	5.20%
Effective Income Tax Rate Reconciliation, Tax Contingency, Other, Percent	(0.00%)		(0.00%)		(0.00%)	(0.00%)
Domestic production activities deduction	(0.00%)		(0.00%)		(0.00%)	(0.00%)
Effective Income Tax Rate Reconciliation, Deduction, Medicare Prescription Drug Benefit, Percent	0.00%		0.00%		0.00%	0.00%
Amortization of investment tax credit, including deferred taxes on basis difference	(0.60%)		(0.30%)		(0.30%)	(0.30%)
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent	1.90%		0.10%		0.60%	0.10%
Production tax credits and other credits	(0.00%)				(0.00%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(0.10%)		(0.00%)		(0.00%)	(0.00%)
Noncontrolling interests	0.00%		0.00%		0.00%	0.00%
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent	(0.00%)		(0.00%)		(0.00%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Other, Percent	27.20%				5.60%
Other(c)	(0.10%)		(0.30%)		(0.00%)	(0.20%)
Effective income tax rate	67.00%				45.10%	40.00%
PECO Energy Co [Member]
Increase (decrease) due to:
U.S. Federal statutory rate	35.00%		35.00%		35.00%	35.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent	2.40%		1.20%		1.30%	1.20%
Effective Income Tax Rate Reconciliation, Tax Contingency, Other, Percent	(0.00%)		(0.00%)		(0.00%)	(0.00%)
Domestic production activities deduction	(0.00%)		(0.00%)		(0.00%)	(0.00%)
Effective Income Tax Rate Reconciliation, Deduction, Medicare Prescription Drug Benefit, Percent	0.00%		0.00%		0.00%	0.00%
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)		(0.10%)		(0.10%)	(0.10%)
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent	6.70%		7.00%		8.80%	7.30%
Production tax credits and other credits	(0.00%)				(0.00%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(0.00%)		(0.00%)		(0.00%)	(0.00%)
Noncontrolling interests	0.00%		0.00%		0.00%	0.00%
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent	(0.00%)		(0.00%)		(0.00%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Other, Percent	0.00%				0.00%
Other(c)	(0.10%)		(0.00%)		1.50%	(0.20%)
Effective income tax rate	30.70%				25.90%	29.00%
Baltimore Gas and Electric Company [Member]
Increase (decrease) due to:
U.S. Federal statutory rate	35.00%		35.00%		35.00%	35.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent	5.20%		5.30%		4.80%	5.30%
Effective Income Tax Rate Reconciliation, Tax Contingency, Other, Percent	(0.00%)		(0.00%)		(0.00%)	(0.00%)
Domestic production activities deduction	(0.00%)		(0.00%)		(0.00%)	(0.00%)
Effective Income Tax Rate Reconciliation, Deduction, Medicare Prescription Drug Benefit, Percent	0.00%		0.20%		0.00%	0.20%
Amortization of investment tax credit, including deferred taxes on basis difference	(0.20%)		(0.20%)		(0.20%)	(0.10%)
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent	0.50%		0.60%		3.30%	0.40%
Production tax credits and other credits	(0.00%)				(0.00%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(0.00%)		(0.00%)		(0.00%)	(0.00%)
Noncontrolling interests	0.00%		0.00%		0.00%	0.00%
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent	(0.00%)		(0.00%)		(0.00%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Other, Percent	0.00%				0.00%
Other(c)	0.40%		0.40%		(0.00%)	0.10%
Effective income tax rate	39.10%				36.30%	39.90%
Pepco Holdings LLC [Member]
Increase (decrease) due to:
Domestic production activities deduction						(0.00%)
Pepco Holdings LLC [Member] | Predecessor [Member]
Increase (decrease) due to:
U.S. Federal statutory rate			35.00%			35.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent			6.20%			7.10%
Effective Income Tax Rate Reconciliation, Tax Contingency, Other, Percent			(0.00%)			(0.00%)
Domestic production activities deduction						(0.00%)
Effective Income Tax Rate Reconciliation, Deduction, Medicare Prescription Drug Benefit, Percent			0.00%			0.00%
Amortization of investment tax credit, including deferred taxes on basis difference			(0.20%)			(0.30%)
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent			3.70%			5.00%
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent			(1.20%)			(1.90%)
Noncontrolling interests						0.00%
Other(c)			1.10%			0.10%
Effective income tax rate			35.00%			34.80%
Pepco Holdings LLC [Member] | Successor [Member]
Increase (decrease) due to:
U.S. Federal statutory rate	35.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent	5.60%
Effective Income Tax Rate Reconciliation, Tax Contingency, Other, Percent	(0.00%)				(0.00%)
Domestic production activities deduction	(0.00%)
Effective Income Tax Rate Reconciliation, Deduction, Medicare Prescription Drug Benefit, Percent	0.00%
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent	5.00%
Production tax credits and other credits	(5.70%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(0.00%)
Noncontrolling interests	0.00%
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent	(0.00%)		(0.00%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Other, Percent	0.00%				0.00%
Other(c)	0.70%
Effective income tax rate	29.10%
Delmarva Power and Light Company [Member]
Increase (decrease) due to:
U.S. Federal statutory rate	35.00%		35.00%		35.00%	35.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent	5.20%		7.40%		310.50%	6.10%
Effective Income Tax Rate Reconciliation, Tax Contingency, Other, Percent	(0.00%)		(0.00%)		(0.00%)	(0.00%)
Domestic production activities deduction	(0.00%)		(0.00%)		(0.00%)	(0.00%)
Effective Income Tax Rate Reconciliation, Deduction, Medicare Prescription Drug Benefit, Percent	0.00%		0.00%			0.00%
Amortization of investment tax credit, including deferred taxes on basis difference	(0.20%)		(0.60%)		(17.90%)	(0.40%)
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent	1.30%		3.50%		98.60%	2.00%
Production tax credits and other credits	(8.60%)				(635.90%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(0.00%)		(0.00%)		(0.00%)	(0.00%)
Noncontrolling interests	0.00%		0.00%			0.00%
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent	(0.00%)		(0.00%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Other, Percent	0.00%				0.00%
Other(c)	(0.10%)		0.80%		(35.10%)	0.50%
Effective income tax rate	30.20%		37.50%		900.00%	38.20%
Potomac Electric Power Company [Member]
Increase (decrease) due to:
U.S. Federal statutory rate	35.00%		35.00%		35.00%	35.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent	5.60%		4.80%		23.00%	4.60%
Effective Income Tax Rate Reconciliation, Tax Contingency, Other, Percent	(0.00%)		(0.00%)		(0.00%)	(0.00%)
Domestic production activities deduction	(0.00%)		(0.00%)		(0.00%)
Effective Income Tax Rate Reconciliation, Deduction, Medicare Prescription Drug Benefit, Percent	0.00%		0.00%			0.00%
Amortization of investment tax credit, including deferred taxes on basis difference	(0.00%)		(0.10%)		(0.20%)	(0.10%)
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent	6.70%		3.50%		29.00%	6.20%
Production tax credits and other credits	(2.30%)				(36.70%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(0.00%)		(0.00%)		(0.00%)	(0.00%)
Noncontrolling interests	0.00%		0.00%			0.00%
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent	(0.00%)		(0.00%)		(0.00%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Other, Percent	0.00%				0.00%
Other(c)	0.90%		1.40%		2.50%	0.70%
Effective income tax rate	30.70%		34.80%		63.00%	32.60%
Atlantic City Electric Company [Member]
Increase (decrease) due to:
U.S. Federal statutory rate	35.00%		35.00%		35.00%	35.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent	6.10%		5.40%		5.50%	5.50%
Effective Income Tax Rate Reconciliation, Tax Contingency, Other, Percent	(0.00%)		(0.00%)		(0.00%)	(0.00%)
Domestic production activities deduction	(0.00%)		(0.00%)		(0.00%)	(0.00%)
Effective Income Tax Rate Reconciliation, Deduction, Medicare Prescription Drug Benefit, Percent	0.00%		0.00%			0.00%
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)		(0.30%)		(0.50%)	(0.50%)
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent	4.60%		3.10%		(7.80%)	2.50%
Production tax credits and other credits	(2.90%)				(35.40%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	(0.00%)		(0.00%)		(0.00%)	(0.00%)
Noncontrolling interests	0.00%		0.00%			0.00%
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent					(0.00%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Other, Percent	0.00%				0.00%
Other(c)	0.60%		(1.90%)		(0.40%)	(0.80%)
Effective income tax rate	32.90%		38.90%		13.80%	38.30%
Atlantic City Electric Company [Member] | Predecessor [Member]
Increase (decrease) due to:
Production tax credits and other credits		(11.10%)
Atlantic City Electric Company [Member] | Successor [Member]
Increase (decrease) due to:
U.S. Federal statutory rate		35.00%		35.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent		11.90%		4.40%
Domestic production activities deduction		(0.00%)		(0.00%)
Amortization of investment tax credit, including deferred taxes on basis difference		0.90%		0.50%
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent		13.50%		(17.50%)
Production tax credits and other credits				(49.80%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent		(0.00%)		(0.00%)
Noncontrolling interests		0.00%
Other(c)		(3.60%)		(1.40%)
Effective income tax rate		47.20%		9.00%

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Mar. 31, 2014	Sep. 30, 2016	Dec. 31, 2015	Mar. 31, 2013	Dec. 31, 2009
Income Tax Additional Narrative Information [Line Items]
Unrecognized Tax Benefits	$ 937			$ 937	$ 1,101
Payments for Other Taxes				1,000
Unrecognized Tax Benefits, Period Increase (Decrease)	328			164
Deferred Gain on Sale of Property							$ 1,200
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	251			251
IRS asserted penalties for understatement of tax	90
Expected non-cash charge to earnings						$ 265
Early termination amount		$ 200
Taxes Payable, Current		150
Income Taxes Receivable	80			80
Unrecognized Tax Benefits, Income Tax Penalties Accrued	1,400			1,400
Tax Adjustments, Settlements, and Unusual Provisions				300
Parent Company [Member]
Income Tax Additional Narrative Information [Line Items]
Unrecognized Tax Benefits, Increase Resulting from Settlements with Taxing Authorities				1
Exelon Generation Co L L C [Member]
Income Tax Additional Narrative Information [Line Items]
Unrecognized Tax Benefits	516			516	534
Unrecognized tax benefits that if recognized would affect the effective tax rate	52			52
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	52			52
Tax Adjustments, Settlements, and Unusual Provisions				6
Commonwealth Edison Co [Member]
Income Tax Additional Narrative Information [Line Items]
Unrecognized Tax Benefits	(12)			(12)	142
Unrecognized Tax Benefits, Period Increase (Decrease)	154
Expected non-cash charge to earnings			$ 172
Non-cash equity contributions			$ 172
Taxes Payable, Current		$ 150
Income Taxes Receivable	345			345
Unrecognized Tax Benefits, Income Tax Penalties Accrued	300			300
PECO Energy Co [Member]
Income Tax Additional Narrative Information [Line Items]
Unrecognized Tax Benefits	0			0	0
Baltimore Gas and Electric Company [Member]
Income Tax Additional Narrative Information [Line Items]
Unrecognized Tax Benefits	120			120	120
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	120			120
Pepco Holdings LLC [Member]
Income Tax Additional Narrative Information [Line Items]
Unrecognized Tax Benefits	157			157
Unrecognized Tax Benefits, Period Increase (Decrease)	135
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	79			79
Pepco Holdings LLC [Member] | Predecessor [Member]
Income Tax Additional Narrative Information [Line Items]
Unrecognized Tax Benefits					22
PEPCO Holdings Inc [Member]
Income Tax Additional Narrative Information [Line Items]
Fresh-Start Adjustment, Increase (Decrease), Deferred Income Tax Liabilities, Noncurrent	8			8
Potomac Electric Power Company [Member]
Income Tax Additional Narrative Information [Line Items]
Unrecognized Tax Benefits	79			79	8
Unrecognized Tax Benefits, Period Increase (Decrease)	71
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	59			59
Delmarva Power and Light Company [Member]
Income Tax Additional Narrative Information [Line Items]
Unrecognized Tax Benefits	34			34	3
Unrecognized Tax Benefits, Period Increase (Decrease)	31
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	20			20
Atlantic City Electric Company [Member]
Income Tax Additional Narrative Information [Line Items]
Unrecognized Tax Benefits	22			$ 22	$ 0
Unrecognized Tax Benefits, Period Increase (Decrease)	$ 22

Income Taxes Income Tax Unrecog

Income Taxes Income Tax Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$ 937	$ 1,101
Exelon Generation Co L L C [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	516	534
Commonwealth Edison Co [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	(12)	142
PECO Energy Co [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	0	0
Baltimore Gas and Electric Company [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	120	120
Pepco Holdings LLC [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	157
Pepco Holdings LLC [Member] | Predecessor [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits		22
Delmarva Power and Light Company [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	34	3
Potomac Electric Power Company [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	79	8
Atlantic City Electric Company [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$ 22	$ 0

Nuclear Decommissioning - Rollf

Nuclear Decommissioning - Rollforward of Nuclear Decommissioning ARO (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation, Accretion Expense	[1]	$ 333	$ 291
Exelon Generation Co L L C [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation, Accretion Expense	[1]	332	$ 291
Current portion of ARO				$ 7
Exelon Generation Co L L C [Member] | Oyster Creek [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation, Revision of Estimate		60
Exelon Generation Co L L C [Member] | Clinton And Quad Cities [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation, Revision of Estimate		384
Exelon Generation Co L L C [Member] | Nuclear Decommissioning [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Nuclear Decommissioning ARO, Beginning Balance	[2]	8,246
Asset Retirement Obligation, Accretion Expense		325
Asset Retirement Obligation, Liabilities Settled		(6)
Asset Retirement Obligation, Period Increase (Decrease)		763
Asset Retirement Obligation, Revision of Estimate		444
Nuclear Decommissioning ARO, Ending Balance	[2]	9,009
Current portion of ARO		$ 44
[1]	Included in Operating and maintenance expense on the Registrants’ Consolidated Statements of Operations and Comprehensive Income
[2]	Includes $44 million and $7 million for the current portion of the ARO at September 30, 2016 and December 31, 2015, respectively, which is included in Other current liabilities on Exelon’s and Generation’s Consolidated Balance Sheets.

Nuclear Decommissioning (Detail

Nuclear Decommissioning (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Nuclear Decommissioning Additional Narrative Information [Line Items]
Decommissioning Liability, Noncurrent	$ 33	$ 90
Decommissioning Fund Investments	11,076	10,342
Exelon Generation Co L L C [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Decommissioning Liability, Noncurrent	33	90
Decommissioning Fund Investments	11,076	$ 10,342
Nuclear Plant [Member] | Exelon Generation Co L L C [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Decommissioning Liability, Noncurrent	$ 87

Nuclear Decommissioning - Unrea

Nuclear Decommissioning - Unrealized Gains on NDT Funds (Details) - Exelon Generation Co L L C [Member] - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Unrealized Losses On Nuclear Decommissioning Trust Fund Investment [Line Items]
Net unrealized gains (losses) on decommissioning trust funds - regulatory agreement units	[1]	$ 155	$ (301)	$ 286	$ (385)
Net unrealized gains (losses) on decommissioning trust funds - non-regulatory agreement units	[2],[3]	116	$ (218)	216	(274)
Unrealized Gain Loss Investment Income Pledged Assets		$ (5)		$ (2)	$ 9
[1]	Net unrealized gains related to Generation’s NDT funds associated with Regulatory Agreement Units are included in Regulatory liabilities on Exelon’s Consolidated Balance Sheets and Noncurrent payables to affiliates on Generation’s Consolidated Balance Sheets.
[2]	Excludes $(5) million of net unrealized gain related to the Zion Station pledged assets for the three months ended September 30, 2016. Excludes $(2) million and $9 million of net unrealized gain related to the Zion Station pledged assets for the nine months ended September 30, 2016 and 2015, respectively. Net unrealized gains related to Zion Station pledged assets are included in the Payable for Zion Station decommissioning on Exelon’s and Generation’s Consolidated Balance Sheets.
[3]	Net unrealized gains related to Generation’s NDT funds with Non-Regulatory Agreement Units are included within Other, net in Exelon’s and Generation’s Consolidated Statements of Operations and Comprehensive Income.

Nuclear Decommissioning - Asset

Nuclear Decommissioning - Assets, Payables and Withdrawals by ZionSolutions (Details) - USD ($) $ in Millions		9 Months Ended	12 Months Ended
		Sep. 30, 2016	Dec. 31, 2015
Nuclear Decommissioning Additional Narrative Information [Line Items]
Pledged assets for Zion Station decommissioning		$ 135	$ 206
Exelon Generation Co L L C [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Pledged assets for Zion Station decommissioning		135	206
Payable to Zion Solutions	[1]	124	189
Current portion of payable to Zion Solutions	[2]	91	99
Withdrawals by Zion Solutions to pay decommissioning costs	[3]	$ 855	$ 786
[1]	Excludes a liability recorded within Exelon’s and Generation’s Consolidated Balance Sheets related to the tax obligation on the unrealized activity associated with the Zion Station NDT funds. The NDT funds will be utilized to satisfy the tax obligations as gains and losses are realized.
[2]	Included in Other current liabilities within Exelon’s and Generation’s Consolidated Balance Sheets.
[3]	Includes project expenses to decommission Zion Station and estimated tax payments on Zion Station NDT fund earnings.

Retirement Benefits - Narrative

Retirement Benefits - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2016	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Increase in regulatory assets due valuation received by Exelon for its legacy pension and other postretirement benefit obligations.	$ 27
Increase in regulatory liabilities due to updated valuation of Exelon's legacy pension and postretirement benefit obligations	3
Increase (Decrease) in Pension Plan Obligations	35
Increase (Decrease) in Postretirement Obligations	8
Defined Benefit Plan, Accumulated Other Comprehensive Income Net Gains (Losses), after Tax	$ (2)
PHI Pension and Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Increase (Decrease) in Pension Plan Obligations		$ 25
Pension Plan, Defined Benefit [Member] | Exelon Legacy Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected return on assets		7.00%
Discount rate		4.29%
Pension Plan, Defined Benefit [Member] | Pepco Holdings LLC [Member] | PHI Pension and Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected return on assets		6.50%
Discount rate		3.96%
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected return on assets		6.71%
Discount rate		4.29%
Other Postretirement Benefit Plan, Defined Benefit [Member] | Pepco Holdings LLC [Member] | PHI Pension and Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected return on assets		6.75%
Discount rate		3.80%

Retirement Benefits - Calculati

Retirement Benefits - Calculation of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended	9 Months Ended
	Sep. 30, 2016	Mar. 23, 2016	Mar. 22, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2016		Sep. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense						$ 458		$ 476
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 92			$ 82		262	[1]	245
Interest cost	215			178		616	[1]	533
Expected return on assets	(293)			(257)		(847)	[1]	(770)
Amortization of:
Prior service cost (benefit)	3			3		10	[1]	10
Defined Benefit Plan, Actuarial Gain (Loss)	142			142		411	[1]	427
Net periodic benefit cost	159			148		452	[1]	445
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	27			30		80	[1]	89
Interest cost	47			42		138	[1]	125
Expected return on assets	(42)			(38)		(121)	[1]	(113)
Amortization of:
Prior service cost (benefit)	(48)			(43)		(138)	[1]	(130)
Defined Benefit Plan, Actuarial Gain (Loss)	18			20		47	[1]	60
Net periodic benefit cost	$ 2			11		6	[1]	31
Potomac Electric Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense			$ 7			24		22
Pepco Holdings LLC [Member] | Predecessor [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense		$ 23						73
Pepco Holdings LLC [Member] | Successor [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense					$ 58
Pepco Holdings LLC [Member] | Pension Plan, Defined Benefit [Member] | Predecessor [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		12		15				43
Interest cost		26		28				82
Expected return on assets		(30)		(35)				(105)
Amortization of:
Prior service cost (benefit)		0		0				1
Defined Benefit Plan, Actuarial Gain (Loss)		14		16				49
Net periodic benefit cost		22		24				70
Pepco Holdings LLC [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member] | Predecessor [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		1		2				5
Interest cost		6		6				18
Expected return on assets		(5)		(6)				(17)
Amortization of:
Prior service cost (benefit)		(3)		(3)				(9)
Defined Benefit Plan, Actuarial Gain (Loss)		2		2				6
Net periodic benefit cost		$ 1		$ 1				3
Delmarva Power and Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense			4			13		11
Atlantic City Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense			3			$ 11		$ 11
Corporate, Non-Segment [Member] | Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense			$ 9
[1]	(a)PHI net periodic benefit costs for the period prior to the merger are not included in the table above.

Retirement Benefits - Allocated

Retirement Benefits - Allocated Portion of Pension and Postretirement Benefit Plan Costs (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended	9 Months Ended
		Sep. 30, 2016	Mar. 23, 2016	Mar. 22, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense							$ 458	$ 476
Other Pension Plan, Postretirement or Supplemental Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense		$ 161			$ 159		458	476
Corporate, Non-Segment [Member] | Other Pension Plan, Postretirement or Supplemental Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense	[1]	13			14		37	43
Pepco Holdings LLC [Member] | Other Pension Plan, Postretirement or Supplemental Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense		28				$ 58
Pepco Holdings LLC [Member] | Corporate, Non-Segment [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense				$ 9
Pepco Holdings LLC [Member] | Corporate, Non-Segment [Member] | Other Pension Plan, Postretirement or Supplemental Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense	[1],[2]	12			12		33	29
Exelon Generation Co L L C [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense							163	200
Exelon Generation Co L L C [Member] | Other Pension Plan, Postretirement or Supplemental Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense		54			67		163	200
Commonwealth Edison Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense							124	155
Commonwealth Edison Co [Member] | Other Pension Plan, Postretirement or Supplemental Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense		41			52		124	155
PECO Energy Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense							25	29
PECO Energy Co [Member] | Other Pension Plan, Postretirement or Supplemental Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense		8			10		25	29
Baltimore Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense							50	49
Baltimore Gas and Electric Company [Member] | Other Pension Plan, Postretirement or Supplemental Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense		17			16		51	49
Potomac Electric Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense				7			24	22
Potomac Electric Power Company [Member] | Other Pension Plan, Postretirement or Supplemental Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense	[2]	8			7		24	22
Delmarva Power and Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense				4			13	11
Delmarva Power and Light Company [Member] | Other Pension Plan, Postretirement or Supplemental Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense	[2]	4			3		13	11
Atlantic City Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense				$ 3			11	11
Atlantic City Electric Company [Member] | Other Pension Plan, Postretirement or Supplemental Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense	[2]	$ 4			3		$ 11	11
Predecessor [Member] | Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense			$ 23					73
Predecessor [Member] | Pepco Holdings LLC [Member] | Other Pension Plan, Postretirement or Supplemental Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense			$ 23		$ 25			$ 73
Successor [Member] | Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense						$ 58
[1]	These amounts primarily represent amounts billed to Exelon’s subsidiaries through intercompany allocations. These amounts are not included in the Generation, ComEd, PECO, BGE, PHI, Pepco, DPL or ACE amounts above.
[2]	Pepco's, DPL's, ACE's and PHISCO's pension and postretirement benefit costs for the nine months ended September 30, 2016 include $7 million, $4 million, $3 million and $9 million, respectively, of costs incurred prior to the closing of Exelon’s merger with PHI on March 23, 2016.

Retirement Benefits - Defined C

Retirement Benefits - Defined Contribution Savings Plans (Details) - USD ($) $ in Millions		3 Months Ended						6 Months Ended	9 Months Ended
		Sep. 30, 2016		Mar. 23, 2016	Mar. 22, 2016	Sep. 30, 2015		Sep. 30, 2016	Sep. 30, 2016		Sep. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions		$ 51				$ 51			$ 107		$ 111
Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions		3						$ 7
Exelon Generation Co L L C [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions		31				27			56		60
Commonwealth Edison Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions		10				10			23		23
PECO Energy Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions		3				3			7		7
Baltimore Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions		2				5			5		10
Business Services Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions	[1]	2				6			9		11
Potomac Electric Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions		0	[2]		$ 1	0	[2]		2	[2]	2	[2]
Delmarva Power and Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions		1	[2]		1	1	[2]		2	[2]	2	[2]
Atlantic City Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions	[2]	0				0			1		1
Predecessor [Member] | Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions				$ 3		3					10
Corporate, Non-Segment [Member] | Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions	[1],[2]	$ 2			$ 1	$ 2			$ 5		$ 5
[1]	These amounts primarily represent amounts billed to Exelon and PHI's subsidiaries through intercompany allocations. These costs are not included in the Generation, ComEd, PECO, BGE, Pepco and DPL amounts above.
[2]	Pepco's, DPL's and PHISCO's matching contributions for the nine months ended September 30, 2016 include $1 million, $1 million,and $1 million, respectively, of costs incurred prior to the closing of Exelon’s merger with PHI on March 23, 2016, which is not included in Exelon’s matching contributions for the nine months ended September 30, 2016.

Severance - Narrative (Details)

Severance - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Restructuring Cost and Reserve [Line Items]
Severance Costs	$ 8	$ (3)	$ 12	$ 18
Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	(2)		44
Exelon Generation Co L L C [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	7	$ (3)	10	$ 17
Exelon Generation Co L L C [Member] | Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	(2)		44
Exelon Generation Co L L C [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	1		$ 2
Exelon Generation Co L L C [Member] | Corporate, Non-Segment [Member] | Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	$ 2

Severance - Ongoing Severance P

Severance - Ongoing Severance Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	$ 8	$ (3)	$ 12	$ 18
Regulatory Assets	11,432		11,432		$ 6,824
Exelon Generation Co L L C [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	7	(3)	10	$ 17
Exelon Generation Co L L C [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	1		2
Commonwealth Edison Co [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	0	$ 0	1
Regulatory Assets	1,192		1,192		1,113
Commonwealth Edison Co [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			1
PECO Energy Co [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Regulatory Assets	1,688		1,688		1,617
Baltimore Gas and Electric Company [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Regulatory Assets	722		722		781
Pepco Holdings LLC [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	1		1
Pepco Holdings LLC [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			1
Potomac Electric Power Company [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Regulatory Assets	798		798		801
Delmarva Power and Light Company [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Regulatory Assets	359		359		371
Atlantic City Electric Company [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Regulatory Assets	$ 501		$ 501		$ 512

Severance - PHI Merger (Details

Severance - PHI Merger (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	$ 8	$ (3)	$ 12	$ 18
PHI Merger [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			55
Exelon Generation Co L L C [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	7	(3)	10	$ 17
Exelon Generation Co L L C [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	1		2
Exelon Generation Co L L C [Member] | PHI Merger [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			9
Exelon Generation Co L L C [Member] | PHI Merger [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			8
Commonwealth Edison Co [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	0	$ 0	1
Commonwealth Edison Co [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			1
Commonwealth Edison Co [Member] | PHI Merger [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			2
Commonwealth Edison Co [Member] | PHI Merger [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			2
PECO Energy Co [Member] | PHI Merger [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			1
PECO Energy Co [Member] | PHI Merger [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			1
Baltimore Gas and Electric Company [Member] | PHI Merger [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			1
Baltimore Gas and Electric Company [Member] | PHI Merger [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			1
Pepco Holdings LLC [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	$ 1		1
Pepco Holdings LLC [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			1
Pepco Holdings LLC [Member] | PHI Merger [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			42
Potomac Electric Power Company [Member] | PHI Merger [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			20
Potomac Electric Power Company [Member] | PHI Merger [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			19
Delmarva Power and Light Company [Member] | PHI Merger [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			12
Delmarva Power and Light Company [Member] | PHI Merger [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			11
Atlantic City Electric Company [Member] | PHI Merger [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			10
Atlantic City Electric Company [Member] | PHI Merger [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			$ 10

Severance - Severance Liabiliti

Severance - Severance Liabilities (Details) $ in Millions	9 Months Ended
	Sep. 30, 2016USD ($)
Restructuring Reserve [Roll Forward]
Beginning Balance	$ 35
Severance Charges Expense	(136)
Payments for Restructuring	(39)
Ending Balance	132
Exelon Generation Co L L C [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	23
Severance Charges Expense	(63)
Payments for Restructuring	(7)
Ending Balance	79
Commonwealth Edison Co [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	3
Severance Charges Expense	(1)
Payments for Restructuring	(1)
Ending Balance	3
PECO Energy Co [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	0
Severance Charges Expense	0
Payments for Restructuring	0
Ending Balance	0
Baltimore Gas and Electric Company [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	1
Severance Charges Expense	0
Payments for Restructuring	(1)
Ending Balance	0
Pepco Holdings LLC [Member]
Restructuring Reserve [Roll Forward]
Ending Balance	28
Potomac Electric Power Company [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	0
Severance Charges Expense	(1)
Payments for Restructuring	(1)
Ending Balance	0
Delmarva Power and Light Company [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	0
Severance Charges Expense	(1)
Payments for Restructuring	(1)
Ending Balance	0
Atlantic City Electric Company [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	0
Severance Charges Expense	0
Payments for Restructuring	0
Ending Balance	0
Successor [Member] | Pepco Holdings LLC [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	0
Severance Charges Expense	53
Payments for Restructuring	$ (25)

Severance Severance - Cost Mana

Severance Severance - Cost Management Program-Related (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Restructuring Cost and Reserve [Line Items]
Severance Costs	$ 8		$ (3)	$ 12	$ 18
Cost Management Project [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs		$ 17		18
PECO Energy Co [Member] | Cost Management Project [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs				1
PECO Energy Co [Member] | Corporate, Non-Segment [Member] | Cost Management Project [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs				1
Exelon Generation Co L L C [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	7		(3)	10	$ 17
Exelon Generation Co L L C [Member] | Cost Management Project [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	1			13
Exelon Generation Co L L C [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	1			2
Exelon Generation Co L L C [Member] | Corporate, Non-Segment [Member] | Cost Management Project [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs				7
Commonwealth Edison Co [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	0		$ 0	1
Commonwealth Edison Co [Member] | Cost Management Project [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs				3
Commonwealth Edison Co [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs				1
Commonwealth Edison Co [Member] | Corporate, Non-Segment [Member] | Cost Management Project [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs				3
Baltimore Gas and Electric Company [Member] | Cost Management Project [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs				1
Baltimore Gas and Electric Company [Member] | Corporate, Non-Segment [Member] | Cost Management Project [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs				1
Pepco Holdings LLC [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	$ 1			1
Pepco Holdings LLC [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs				$ 1

Mezzanine Equity Mezzanine E101

Mezzanine Equity Mezzanine Equity (Details) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Mar. 23, 2016
Redeemable Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Common, Carrying Amount	$ 26,000,000		$ 28,000,000
Temporary Equity, Other Changes	107,000,000
Preferred Stock, Shares Subscribed but Unissued, Value [Abstract]
Number of preferred shares purchased			18,000
Payments to Acquire Businesses, Gross	6,896,000,000	$ 28,000,000
Preferred Stock [Member]
Preferred Stock, Shares Subscribed but Unissued, Value [Abstract]
Payments to Acquire Businesses, Gross			$ 180,000,000
Exelon Generation Co L L C [Member]
Redeemable Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Common, Carrying Amount	26,000,000		28,000,000
Temporary Equity, Other Changes	(107,000,000)
Noncontrolling Interest, Increase from Sale of Parent Equity Interest	105,000,000
Preferred Stock, Shares Subscribed but Unissued, Value [Abstract]
Payments to Acquire Businesses, Gross	$ 255,000,000	$ 28,000,000
Pepco Holdings LLC [Member]
Preferred Stock, Shares Subscribed but Unissued, Value [Abstract]
Derivative, Fair Value, Net				$ 0
Increase (Decrease) in Derivative Assets			$ 18,000,000

Changes in Accumulated Other102

Changes in Accumulated Other Comprehensive Income - Schedule of Changes in AOCI (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2016		Sep. 30, 2015		Sep. 30, 2016		Sep. 30, 2015		Dec. 31, 2015		Dec. 31, 2014
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	$ (2,523)		$ (2,596)		$ (2,523)		$ (2,596)		$ (2,624)		$ (2,684)
OCI before reclassifications	[1]					(5)		(64)
Amounts reclassified from AOCI	[1],[2]					106		152
Net current-period OCI		36		32		96		88	[1]
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	(23)		(24)		(23)		(24)		(19)		(28)
OCI before reclassifications	[1]					(1)		(18)
Amounts reclassified from AOCI	[1],[2]					(3)		22
Net current-period OCI	[1]					(4)		4
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		3	[1]	3	[1]	3	[1]	3	[1]	3	[1]	3
OCI before reclassifications	[1]					0		0
Net current-period OCI	[1]					0		0
Accumulated Defined Benefit Plans Adjustment [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	(2,463)		(2,539)		(2,463)		(2,539)		(2,565)		(2,640)
OCI before reclassifications						(2)	[1]	(29)
Amounts reclassified from AOCI	[1],[2]					104		130
Net current-period OCI	[1]					102		101
Accumulated Translation Adjustment [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(32)	[1]	(36)	[1]	(32)	[1]	(36)	[1]	(40)	[1]	(19)
OCI before reclassifications	[1]					3		(17)
Amounts reclassified from AOCI						(5)
Net current-period OCI	[1]					8		(17)
Accumulated Equity Investment [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	(8)		0		(8)		0		(3)		0
OCI before reclassifications	[1]					(5)		0
Amounts reclassified from AOCI	[1],[2]					0		0
Net current-period OCI	[1]					(5)		0
AOCI Attributable to Parent [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Net current-period OCI	[1]					101
Exelon Generation Co L L C [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	(56)		(60)		(56)		(60)		(63)		(36)
OCI before reclassifications	[1]					5		(30)
Amounts reclassified from AOCI	[1],[2]					2		6
Net current-period OCI		4		(13)		2		(24)	[1]
Exelon Generation Co L L C [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(24)	[1]	(25)	[1]	(24)	[1]	(25)	[1]	(21)		(18)
OCI before reclassifications	[1]					0		(13)
Amounts reclassified from AOCI	[1],[2]					(3)		6
Net current-period OCI	[1]					(3)		(7)
Exelon Generation Co L L C [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		2	[1]	1	[1]	2	[1]	1	[1]	1		1	[1]
OCI before reclassifications	[1]					1		0
Net current-period OCI	[1]					1		0
Exelon Generation Co L L C [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]			0				0				0
Exelon Generation Co L L C [Member] | Accumulated Translation Adjustment [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(32)	[1]	(36)	[1]	(32)	[1]	(36)	[1]	(40)	[1]	(19)
OCI before reclassifications	[1]					3		(17)
Net current-period OCI	[1]					8		(17)
Exelon Generation Co L L C [Member] | Accumulated Equity Investment [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	(2)		0		(2)		0		(3)		0
OCI before reclassifications	[1]					1		0
Amounts reclassified from AOCI	[1],[2]					0		0
Net current-period OCI	[1]					1		0
Exelon Generation Co L L C [Member] | AOCI Attributable to Parent [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(56)				(56)				(63)
Net current-period OCI	[1]					7
PECO Energy Co [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	1		1		1		1		1		1
Net current-period OCI	[1]							0
PECO Energy Co [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	0		0		0		0		0		0
OCI before reclassifications	[1]							0
PECO Energy Co [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		1	[1]	1	[1]	1	[1]	1	[1]	1	[1]	1
OCI before reclassifications	[1]							0
PECO Energy Co [Member] | Accumulated Translation Adjustment [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
OCI before reclassifications	[1]							0
PECO Energy Co [Member] | Accumulated Equity Investment [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
OCI before reclassifications	[1]							0
PEPCO Holdings Inc [Member] | Predecessor [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(35)	[3]	(41)		(35)	[3]	(41)		(36)		(46)
OCI before reclassifications						0		0
Amounts reclassified from AOCI						1		5
Net current-period OCI						1		5
PEPCO Holdings Inc [Member] | Predecessor [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(8)	[3]	(8)		(8)	[3]	(8)		(8)		(9)
OCI before reclassifications						0		0
Amounts reclassified from AOCI						0		(1)
Net current-period OCI						0		1
PEPCO Holdings Inc [Member] | Predecessor [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		0	[3]	0		0	[3]	0		0		0
OCI before reclassifications						0		0
Amounts reclassified from AOCI						0
Net current-period OCI						0		0
PEPCO Holdings Inc [Member] | Predecessor [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(27)	[3]	(33)		(27)	[3]	(33)		(28)		(37)
OCI before reclassifications						0		0
Amounts reclassified from AOCI						1		4
Net current-period OCI						1		4
PEPCO Holdings Inc [Member] | Predecessor [Member] | Accumulated Translation Adjustment [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		0	[3]	0		0	[3]	0		0		0
OCI before reclassifications						0		0
Amounts reclassified from AOCI						0		0
Net current-period OCI						0		0
PEPCO Holdings Inc [Member] | Predecessor [Member] | Accumulated Equity Investment [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		$ 0	[3]	$ 0		0	[3]	0		$ 0		$ 0
OCI before reclassifications						0		0
Amounts reclassified from AOCI						0		0
Net current-period OCI						$ 0		$ 0
[1]	All amounts are net of tax and noncontrolling interest. Amounts in parenthesis represent a decrease in AOCI.
[2]	See next tables for details about these reclassifications.
[3]	As a result of the PHI Merger, the PHI predecessor balances at March 23, 2016 were reduced to zero on March 24, 2016 due to purchase accounting adjustments applied to PHI.

Changes in Accumulated Other103

Changes in Accumulated Other Comprehensive Income - Reclassification out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2016		Sep. 30, 2015		Sep. 30, 2016		Sep. 30, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues		$ 9,002		$ 7,401		$ 23,486		$ 22,746
Income before income taxes		871		703		1,597		2,767
Income taxes		(340)		(115)		(625)		(805)
Net income		526		587		956		1,959
Comprehensive Income (Loss), Net of Tax, Attributable to Parent		562		619		1,052		2,047
Other, net		120		(244)		377		(179)
Equity in (losses) earnings of unconsolidated affiliates						(15)		(3)
Interest Expense		506		243		1,148		724
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	[1]	(5)				(5)
Income taxes	[1]	0				0
Net income	[1]	(5)		(46)		(5)		(152)
Other, net		(5)				(5)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	[1]			(4)		5		(35)
Income taxes	[1]			1		(2)		13
Net income	[1]			(3)		3		(22)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Energy Related Derivative [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues	[1]							2
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Cash Flow Hedging [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income taxes	[1]					2		10
Interest Expense						5		(11)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Interest Rate Swap [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other, net	[1]							(26)
Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	[1]	(57)		(71)		(170)		(213)
Income taxes		22	[1]	28	[1]	66	[1]	83
Net income	[1]	(35)		(43)		(104)		(130)
Prior service benefit reclassified to periodic benefit cost		19		19		57		57
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax	[1],[2]	(76)		(90)		(227)		(270)
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income	[1]					(106)
Exelon Generation Co L L C [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues		5,035		4,768		13,363		14,841
Income before income taxes		450		297		865		1,583
Income taxes		(173)		36		(293)		(371)
Net income		271		332		556		1,208
Comprehensive Income (Loss), Net of Tax, Attributable to Parent		275		319		558		1,184
Other, net		185		(257)		395		(193)
Equity in (losses) earnings of unconsolidated affiliates						(16)		(4)
Interest Expense		67		56		243		236
Exelon Generation Co L L C [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	[1]	(5)				(5)
Income taxes	[1]	0				0
Net income	[1]	(5)		(3)		(5)		(6)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	[1]	(5)
Other, net		(5)				(5)
Exelon Generation Co L L C [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	[1]			(4)		5		(9)
Income taxes				1	[1]	(2)	[1]	(3)
Net income	[1]			(3)		3		(6)
Exelon Generation Co L L C [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Energy Related Derivative [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues	[1]							2
Exelon Generation Co L L C [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Cash Flow Hedging [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest Expense						5		(11)
Exelon Generation Co L L C [Member] | Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income	[1]					(2)
PEPCO Holdings Inc [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income				(1)				(5)
PEPCO Holdings Inc [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Energy Related Derivative [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues								0
Income before income taxes				(1)		0		(1)
Income taxes				0		0		0
Net income				(1)		0		(1)
PEPCO Holdings Inc [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Cash Flow Hedging [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues						0
Interest Expense				(1)				(1)
PEPCO Holdings Inc [Member] | Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes				(2)		(1)		(7)
Income taxes				(2)		0		3
Net income				0		(1)		(4)
Prior service benefit reclassified to periodic benefit cost				0		0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax				(2)		(1)		(7)
Potomac Electric Power Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues		635		592		1,695		1,641
Income before income taxes		114		92		54		190
Income taxes		(35)		(32)		(34)		(62)
Net income		79		60		20		128
Comprehensive Income (Loss), Net of Tax, Attributable to Parent		79		60		20		128
Other, net		12		8		28		21
Equity in (losses) earnings of unconsolidated affiliates						0		0
Interest Expense		30		31		98		92
Delmarva Power and Light Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues		331		314		974		1,004
Income before income taxes		63		24		2		89
Income taxes		(19)		(9)		(18)		(34)
Net income		44		15		(16)		55
Comprehensive Income (Loss), Net of Tax, Attributable to Parent		44		15		(16)		55
Other, net		3		4		9		8
Equity in (losses) earnings of unconsolidated affiliates						0		0
Interest Expense		12		12		37		37
Atlantic City Electric Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues		421		386		982		1,003
Income before income taxes		70		36		(58)		60
Income taxes		(23)		(14)		8		(23)
Net income		47		22		(50)		37
Comprehensive Income (Loss), Net of Tax, Attributable to Parent		47		22		(50)		37
Other, net		2		1		8		4
Equity in (losses) earnings of unconsolidated affiliates						0		0
Interest Expense		$ 15		16		$ 47		$ 48
Interest Expense [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest Expense				(4)
Interest Expense [Member] | Exelon Generation Co L L C [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest Expense				$ (4)
[1]	Amounts in parenthesis represent a decrease in net income.
[2]	This AOCI component is included in the computation of net periodic pension and OPEB cost (see Note 13 — Retirement Benefits for additional details).

Changes in Accumulated Other104

Changes in Accumulated Other Comprehensive Income - Components of Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Mar. 23, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension and non-pension postretirement benefit plans:
Prior service benefit reclassified to periodic benefit cost	$ 7		$ 8	$ 22	$ 22
Actuarial loss reclassified to periodic cost	(29)		(35)	(88)	(105)
Pension and non-pension postretirement benefit plans valuation adjustment	1		0	1	17
Change in unrealized gain/(loss) on cash flow hedges	(1)		3	3	(3)
Change in unrealized loss on equity investments	0		0	3	0
Change in unrealized gain on marketable securities	(1)		0	(1)	0
Total	(23)		(24)	(60)	(69)
PEPCO Holdings Inc [Member]
Pension and non-pension postretirement benefit plans:
Actuarial loss reclassified to periodic cost	2	$ 0			3
Exelon Generation Co L L C [Member]
Pension and non-pension postretirement benefit plans:
Change in unrealized gain/(loss) on cash flow hedges	(2)		3	1	4
Change in unrealized loss on equity investments	0		0	3	0
Change in unrealized gain on marketable securities	0		0	0	0
Total	$ (2)		$ 3	$ 4	$ 4

Earnings Per Share and Equity -

Earnings Per Share and Equity - Schedule of Earnings per Share (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 490	$ 629	$ 930	$ 1,959
Weighted average common shares outstanding — basic	925	913	924	879
Assumed exercise and/or distributions of stock-based awards	2	2	2	4
Weighted average common shares outstanding — diluted	927	915	926	883

Earnings Per Share and Equit106

Earnings Per Share and Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	Sep. 18, 2016	Jul. 03, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Oct. 01, 2015
Statement Of Equity Line Item [Line Items]
Treasury Stock, Shares held			35,000,000		35,000,000
Treasury Stock, Value			$ (2,327)		$ (2,327)		$ (2,327)
Preferred Stock, Value, Issued			$ 0		$ 0		193
Stock Redeemed or Called During Period, Shares	500,000	400,000	600,000		400,000
Preferred Stock, Dividend Rate, Percentage	6.97%	7.125%	6.99%		6.70%
Equity units issued [Member]
Statement Of Equity Line Item [Line Items]
Stock options not included in the calculation of diluted common shares outstanding			1,000,000	4,000,000	1,000,000	2,000,000
Employee Stock Option [Member]
Statement Of Equity Line Item [Line Items]
Stock options not included in the calculation of diluted common shares outstanding			11,000,000	14,000,000	12,000,000	14,000,000
Baltimore Gas and Electric Company [Member]
Statement Of Equity Line Item [Line Items]
Preferred Stock, Redemption Price Per Share			$ 100		$ 100
Preferred Stock, Value, Issued			$ 0		$ 0		$ 190	$ 190
Stock Redeemed or Called During Period, Value	$ 90	$ 100

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Equity Investment Commitments (Details) - Exelon Generation Co L L C [Member] $ in Millions	Sep. 30, 2016USD ($)
Equity Unit Purchase Agreements [Member]
Guarantor Obligations [Line Items]
Other Unrecorded Amounts	$ 20
Unrecorded Unconditional Purchase Obligation, Due in Next Twelve Months	79
2,015	25
2,016	4
Total	108
Noncontrolling Interest [Member]
Guarantor Obligations [Line Items]
Other Unrecorded Amounts	$ 31

Commitments and Contingencie108

Commitments and Contingencies - Commitments Narrative (Details) $ in Millions		3 Months Ended	9 Months Ended
		Sep. 30, 2016USD ($)	Sep. 30, 2016USD ($)MW	Jun. 30, 2013USD ($)
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted		$ 50	$ 50
Noncash Merger Related Costs	[1],[2]		$ 508
Power Volume | MW			220
Exelon Generation Co L L C [Member]
Guarantor Obligations [Line Items]
Noncash Merger Related Costs	[2]		$ 3
Costs Incurred, Development Costs		404
Minimum [Member] | Exelon Generation Co L L C [Member]
Guarantor Obligations [Line Items]
Business Acquisition, Development Of New Generation Cost		450	$ 450
Business Acquisition, Expected New Generation Mwh | MW			275
Maximum [Member] | Exelon Generation Co L L C [Member]
Guarantor Obligations [Line Items]
Business Acquisition, Development Of New Generation Cost		550	$ 550
Business Acquisition, Expected New Generation Mwh | MW			300
Noncash Merger Related Costs			$ 105
Equity Unit Purchase Agreements [Member] | Exelon Generation Co L L C [Member]
Guarantor Obligations [Line Items]
2,015		$ 25	$ 25
Merger Commitment [Member]
Guarantor Obligations [Line Items]
Investments				$ 1,000
Merger Commitment [Member] | Minimum [Member]
Guarantor Obligations [Line Items]
Investments				0
Merger Commitment [Member] | Maximum [Member]
Guarantor Obligations [Line Items]
Investments				$ 0
[1]	(e)Excludes $5 million of forgiveness of Accounts receivable related to merger commitments recorded in connection with the PHI Merger, the balance is included within Provision for uncollectible accounts.
[2]	See Note 4 — Mergers, Acquisitions and Dispositions for additional information related to the merger with PHI.

Commitments and Contingencie109

Commitments and Contingencies - Schedule of Commercial Commitments (Details) - USD ($) $ in Millions	Sep. 30, 2016	Aug. 31, 2016	Mar. 31, 2016	Jul. 31, 2014
Guarantor Obligations [Line Items]
Other Commitment	$ 6,497	$ 513	$ 508
Guarantor Obligations, Maximum Exposure, Undiscounted	50
Financial Standby Letter of Credit [Member]
Guarantor Obligations [Line Items]
Other Commitment	1,720
Guarantee of Indebtedness of Others [Member]
Guarantor Obligations [Line Items]
Other Commitment	628
Surety Bond [Member]
Guarantor Obligations [Line Items]
Other Commitment	1,084
Nuclear Insurance Premiums [Member]
Guarantor Obligations [Line Items]
Other Commitment	3,045
GuaranteedLeaseResidualValues [Member]
Guarantor Obligations [Line Items]
Other Commitment	20
Exelon Generation Co L L C [Member]
Guarantor Obligations [Line Items]
Other Commitment	5,679			$ 91
Exelon Generation Co L L C [Member] | Financial Standby Letter of Credit [Member]
Guarantor Obligations [Line Items]
Other Commitment	1,650
Exelon Generation Co L L C [Member] | Guarantee of Indebtedness of Others [Member]
Guarantor Obligations [Line Items]
Other Commitment	0
Exelon Generation Co L L C [Member] | Surety Bond [Member]
Guarantor Obligations [Line Items]
Other Commitment	984
Exelon Generation Co L L C [Member] | Nuclear Insurance Premiums [Member]
Guarantor Obligations [Line Items]
Other Commitment	3,045
Commonwealth Edison Co [Member]
Guarantor Obligations [Line Items]
Other Commitment	226
Commonwealth Edison Co [Member] | Financial Standby Letter of Credit [Member]
Guarantor Obligations [Line Items]
Other Commitment	16
Commonwealth Edison Co [Member] | Guarantee of Indebtedness of Others [Member]
Guarantor Obligations [Line Items]
Other Commitment	200
Commonwealth Edison Co [Member] | Surety Bond [Member]
Guarantor Obligations [Line Items]
Other Commitment	10
Commonwealth Edison Co [Member] | GuaranteedLeaseResidualValues [Member]
Guarantor Obligations [Line Items]
Other Commitment	0
PECO Energy Co [Member]
Guarantor Obligations [Line Items]
Other Commitment	210
PECO Energy Co [Member] | Financial Standby Letter of Credit [Member]
Guarantor Obligations [Line Items]
Other Commitment	23
PECO Energy Co [Member] | Guarantee of Indebtedness of Others [Member]
Guarantor Obligations [Line Items]
Other Commitment	178
PECO Energy Co [Member] | Surety Bond [Member]
Guarantor Obligations [Line Items]
Other Commitment	9
PECO Energy Co [Member] | GuaranteedLeaseResidualValues [Member]
Guarantor Obligations [Line Items]
Other Commitment	0
Baltimore Gas and Electric Company [Member]
Guarantor Obligations [Line Items]
Other Commitment	263
Baltimore Gas and Electric Company [Member] | Financial Standby Letter of Credit [Member]
Guarantor Obligations [Line Items]
Other Commitment	2
Baltimore Gas and Electric Company [Member] | Guarantee of Indebtedness of Others [Member]
Guarantor Obligations [Line Items]
Other Commitment	250
Baltimore Gas and Electric Company [Member] | Surety Bond [Member]
Guarantor Obligations [Line Items]
Other Commitment	11
Baltimore Gas and Electric Company [Member] | GuaranteedLeaseResidualValues [Member]
Guarantor Obligations [Line Items]
Other Commitment	0
PEPCO Holdings Inc [Member]
Guarantor Obligations [Line Items]
Other Commitment	37
PEPCO Holdings Inc [Member] | Financial Standby Letter of Credit [Member]
Guarantor Obligations [Line Items]
Other Commitment	1
PEPCO Holdings Inc [Member] | Guarantee of Indebtedness of Others [Member]
Guarantor Obligations [Line Items]
Other Commitment	0
PEPCO Holdings Inc [Member] | Surety Bond [Member]
Guarantor Obligations [Line Items]
Other Commitment	16
PEPCO Holdings Inc [Member] | Nuclear Insurance Premiums [Member]
Guarantor Obligations [Line Items]
Other Commitment	0
PEPCO Holdings Inc [Member] | GuaranteedLeaseResidualValues [Member]
Guarantor Obligations [Line Items]
Other Commitment	20
Potomac Electric Power Company [Member]
Guarantor Obligations [Line Items]
Other Commitment	15
Guarantor Obligations, Maximum Exposure, Undiscounted	13
Potomac Electric Power Company [Member] | Financial Standby Letter of Credit [Member]
Guarantor Obligations [Line Items]
Other Commitment	0
Potomac Electric Power Company [Member] | Guarantee of Indebtedness of Others [Member]
Guarantor Obligations [Line Items]
Other Commitment	0
Potomac Electric Power Company [Member] | Surety Bond [Member]
Guarantor Obligations [Line Items]
Other Commitment	9
Potomac Electric Power Company [Member] | Nuclear Insurance Premiums [Member]
Guarantor Obligations [Line Items]
Other Commitment	0
Potomac Electric Power Company [Member] | GuaranteedLeaseResidualValues [Member]
Guarantor Obligations [Line Items]
Other Commitment	6
Atlantic City Electric Company [Member]
Guarantor Obligations [Line Items]
Other Commitment	9
Guarantor Obligations, Maximum Exposure, Undiscounted	13
Atlantic City Electric Company [Member] | Financial Standby Letter of Credit [Member]
Guarantor Obligations [Line Items]
Other Commitment	1
Atlantic City Electric Company [Member] | Guarantee of Indebtedness of Others [Member]
Guarantor Obligations [Line Items]
Other Commitment	0
Atlantic City Electric Company [Member] | Surety Bond [Member]
Guarantor Obligations [Line Items]
Other Commitment	3
Atlantic City Electric Company [Member] | Nuclear Insurance Premiums [Member]
Guarantor Obligations [Line Items]
Other Commitment	0
Atlantic City Electric Company [Member] | GuaranteedLeaseResidualValues [Member]
Guarantor Obligations [Line Items]
Other Commitment	5
Delmarva Power and Light Company [Member]
Guarantor Obligations [Line Items]
Other Commitment	11
Guarantor Obligations, Maximum Exposure, Undiscounted	17
Delmarva Power and Light Company [Member] | Financial Standby Letter of Credit [Member]
Guarantor Obligations [Line Items]
Other Commitment	0
Delmarva Power and Light Company [Member] | Guarantee of Indebtedness of Others [Member]
Guarantor Obligations [Line Items]
Other Commitment	0
Delmarva Power and Light Company [Member] | Surety Bond [Member]
Guarantor Obligations [Line Items]
Other Commitment	4
Delmarva Power and Light Company [Member] | Nuclear Insurance Premiums [Member]
Guarantor Obligations [Line Items]
Other Commitment	0
Delmarva Power and Light Company [Member] | GuaranteedLeaseResidualValues [Member]
Guarantor Obligations [Line Items]
Other Commitment	$ 7

Commitments and Contingencie110

Commitments and Contingencies - Contingencies Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Commitments And Contingencies Additional Narrative Information [Line Items]
Nuclear Insurance Financial Protection Pool Surcharge On Nuclear Incident Assessment	12730000000.00%
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 50
Exelon Generation Co L L C [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Loss Contingency Accrual	44
Required nuclear liability insurance per site	0
Nuclear financial protection pool value	400
Current Liability Per Incident	13,400
Maximum liability per nuclear incident		$ 13,000
Potomac Electric Power Company [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	13
Nuclear Insurance Premiums [Member] | Exelon Generation Co L L C [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Nuclear financial protection pool value	2,700
Maximum assessment mandated by Price-Anderson Act per nuclear reactor for a nuclear incident	19
Maximum liability per nuclear incident	$ 0

Commitments and Contingencie111

Commitments and Contingencies - Environmental Issues Narrative (Details) $ in Millions	1 Months Ended		3 Months Ended	9 Months Ended
	Aug. 31, 2015gal	Oct. 31, 2007USD ($)	Sep. 30, 2016USD ($)MGPSitegal	Sep. 30, 2016USD ($)DefendantMGPSiteOpen_claimgal
Accrual For Environmental Loss Contingencies [Line Items]
Loss Contingency, Claims Dismissed, Number | Defendant				30
Commonwealth Edison Co [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Total number of MGP sites | MGPSite			17	17
Approved clean-up | MGPSite			42	42
Other Increase (Decrease) in Environmental Liabilities			$ 7
PECO Energy Co [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Total number of MGP sites | MGPSite			16	16
Approved clean-up | MGPSite			26	26
Other Increase (Decrease) in Environmental Liabilities			$ 2
Baltimore Gas and Electric Company [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Approved clean-up | MGPSite			13	13
Exelon Generation Co L L C [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Loss Contingency, New Claims Filed, Number | Open_claim				63
Site Contingency, Loss Exposure Not Accrued, Best Estimate			$ 90
Consent decree penalty		$ 1
Environmental loss contingencies			$ 13	$ 13
PEPCO Holdings Inc [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Sites under study/remediation | MGPSite			9	9
Environmental Remediation Expense				$ 10
PEPCO Holdings Inc [Member] | Minimum [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss			$ 7	7
PEPCO Holdings Inc [Member] | Maximum [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss			$ 18	18
Potomac Electric Power Company [Member]
Accrual For Environmental Loss Contingencies [Line Items]
QuantityOfMineralOilSPill | gal	6,100
Potomac Electric Power Company [Member] | Minimum [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Environmental Exit Costs, Anticipated Cost				3
Potomac Electric Power Company [Member] | Maximum [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Environmental Exit Costs, Anticipated Cost				$ 6
Delmarva Power and Light Company [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Total number of MGP sites | gal			2	2
Calpine Corporation [Member] | Maximum [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss			$ 10	$ 10
Sixty-Eighth Street Dump [Member] | Baltimore Gas and Electric Company [Member] | Minimum [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss			50	50
Sixty-Eighth Street Dump [Member] | Baltimore Gas and Electric Company [Member] | Maximum [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss			64	64
Rossville Ash Site [Member] | Exelon Generation Co L L C [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss			6	6
Sauer Dump Site [Member] | Exelon Generation Co L L C [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss			$ 2	$ 2

Commitments and Contingencie112

Commitments and Contingencies - Litigation and Regulatory Matters (Details) $ in Millions	3 Months Ended
	Sep. 30, 2016USD ($)claimantOpen_claim	Dec. 31, 2015USD ($)
Exelon Generation Co L L C [Member]
Asbestos Loss Contingency [Abstract]
Asbestos liability reserve	$ 22	$ 0
Asbestos liability reserve related to open claims	$ 0
Open asbestos liability claims | Open_claim	61,000,000
Asbestos liability reserve related to anticipated claims	$ 95
Telephone Consumer Protection Act Lawsuit [Abstract]
Loss Contingency Accrual	44
Loss Contingency, Damages Sought, Value	$ 14
Baltimore Gas and Electric Company [Member]
Asbestos Loss Contingency [Abstract]
Number of claimants | claimant	83,000,000

Commitments and Contingencie113

Commitments and Contingencies - Schedule of Accruals for Environmental Matters (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Total Accrual For Environmental Loss Contingencies [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	$ 427	$ 369
Total Accrual For Environmental Loss Contingencies [Member] | Exelon Generation Co L L C [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	76	63
Total Accrual For Environmental Loss Contingencies [Member] | Commonwealth Edison Co [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	283	266
Total Accrual For Environmental Loss Contingencies [Member] | PECO Energy Co [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	36	37
Total Accrual For Environmental Loss Contingencies [Member] | Baltimore Gas and Electric Company [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	2	3
Total Accrual For Environmental Loss Contingencies [Member] | PEPCO Holdings Inc [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	30	33
Total Accrual For Environmental Loss Contingencies [Member] | Potomac Electric Power Company [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	27	24
Total Accrual For Environmental Loss Contingencies [Member] | Delmarva Power and Light Company [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	2	3
Total Accrual For Environmental Loss Contingencies [Member] | Atlantic City Electric Company [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	1	1
Accrual For MGP Investigation And Remediation [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	318	301
Accrual For MGP Investigation And Remediation [Member] | Exelon Generation Co L L C [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	0	0
Accrual For MGP Investigation And Remediation [Member] | Commonwealth Edison Co [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	281	264
Accrual For MGP Investigation And Remediation [Member] | PECO Energy Co [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	34	35
Accrual For MGP Investigation And Remediation [Member] | Baltimore Gas and Electric Company [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	2	2
Accrual For MGP Investigation And Remediation [Member] | PEPCO Holdings Inc [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	1	1
Accrual For MGP Investigation And Remediation [Member] | Potomac Electric Power Company [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	0	0
Accrual For MGP Investigation And Remediation [Member] | Delmarva Power and Light Company [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	1	1
Accrual For MGP Investigation And Remediation [Member] | Atlantic City Electric Company [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	$ 0	$ 0

Supplemental Financial Infor114

Supplemental Financial Information - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2016	Dec. 31, 2015
Supplemental Financial Information Tables [Line Items]
Debt Instrument, Face Amount	$ 750
Gain (Loss) on Sale of Derivatives	26
PECO Energy Co [Member]
Supplemental Financial Information Tables [Line Items]
Financing Receivable, Net		$ 16	$ 15
Financing Receivable, Allowance for Credit Losses		14	$ 15
Low To Medium Risk [Member] | PECO Energy Co [Member]
Supplemental Financial Information Tables [Line Items]
Financing Receivable, Net	1	0
Risk Level, Medium [Member] | PECO Energy Co [Member]
Supplemental Financial Information Tables [Line Items]
Financing Receivable, Net	3	3
Risk Level, High [Member] | PECO Energy Co [Member]
Supplemental Financial Information Tables [Line Items]
Financing Receivable, Net	$ 11	$ 11

Supplemental Financial Infor115

Supplemental Financial Information - Operations (Detail) - USD ($) $ in Millions		3 Months Ended				6 Months Ended	9 Months Ended
		Sep. 30, 2016	Mar. 23, 2016	Sep. 30, 2015		Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes		$ 255		$ 151			$ 624	$ 430
Decommissioning-Related Activities [Abstract]
Net realized income on decommissioning trust funds - Regulatory Agreement Units		57		39	[1]		181	203	[1]
Net realized income on decommissioning trust funds - Non-Regulatory Agreement Units		35		18	[1]		95	122	[1]
Net unrealized income (losses) on decommissioning trust funds - Regulatory Agreement Units		155		(301)			286	(385)
Net unrealized income (losses) on decommissioning trust funds - Non-Regulatory Agreement		116		(218)			216	(274)
Net unrealized income (losses) on pledged assets		(5)					(2)	9
Regulatory offset to decommissioning trust fund-related activities		(168)		207	[2]		(380)	129	[2]
Total decommissioning-related activities		190		(255)			396	(196)
Investment income		2		4			14	6
Long-term lease income				4			4	12
Unrecognized Tax Benefits Interest Income		8					13	0
Income Tax Examination, Penalties and Interest Expense		106					106
AFUDC - equity		19		6			43	16
Gain (Loss) on Disposition of Assets	[3]							(26)
Unrecognized Tax Benefits, Income Tax Penalties Expense		(90)
Gains (Losses) on Extinguishment of Debt							(3)
Other Income		7		(3)			16	9
Other, net		120		(244)			377	(179)
Exelon Generation Co L L C [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes		35		28			90	79
Decommissioning-Related Activities [Abstract]
Net realized income on decommissioning trust funds - Regulatory Agreement Units		57		39	[1]		181	203	[1]
Net realized income on decommissioning trust funds - Non-Regulatory Agreement Units		35		18	[1]		95	122	[1]
Net unrealized income (losses) on decommissioning trust funds - Regulatory Agreement Units		155		(301)			286	(385)
Net unrealized income (losses) on decommissioning trust funds - Non-Regulatory Agreement		116		(218)			216	(274)
Net unrealized income (losses) on pledged assets		(5)					(2)	9
Regulatory offset to decommissioning trust fund-related activities		(168)		207	[2]		(380)	129	[2]
Total decommissioning-related activities		190		(255)			396	(196)
Investment income		1		1			6	1
Unrecognized Tax Benefits Interest Income		0					0	1
Gain (Loss) on Disposition of Assets								0
Gains (Losses) on Extinguishment of Debt							(2)
Other Income		(6)		(3)			(5)	1
Other, net		185		(257)			395	(193)
Commonwealth Edison Co [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes		67		63			186	180
Decommissioning-Related Activities [Abstract]
Investment income		0
Unrecognized Tax Benefits Interest Income							0	0
Income Tax Examination, Penalties and Interest Expense							86
AFUDC - equity		5		1			8	2
Other Income		1		3			6	12
Other, net		(80)		4			(72)	14
PECO Energy Co [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes		40		37			106	104
Decommissioning-Related Activities [Abstract]
Investment income		(1)		(1)			(1)	(1)
Unrecognized Tax Benefits Interest Income		0					0	0
AFUDC - equity		2		1			6	4
Other Income		1		1			1	0
Other, net		2		1			6	3
Baltimore Gas and Electric Company [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes		21		23			66	67
Decommissioning-Related Activities [Abstract]
Investment income		0		1	[4]		2	3	[4]
Unrecognized Tax Benefits Interest Income		0					0
AFUDC - equity		5		4			14	10
Other Income		0		(1)			0	0
Other, net		5		4			16	13
Potomac Electric Power Company [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes		87		82			240	239
Decommissioning-Related Activities [Abstract]
Investment income		0		0			0	0
Long-term lease income				0			0	0
Unrecognized Tax Benefits Interest Income		0					1	0
AFUDC - equity		5		3			14	9
Gain (Loss) on Disposition of Assets		0					8
Other Income		7		5			13	12
Other, net		12		8			28	21
Pepco Holdings LLC [Member] | Successor [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes		92				$ 176
Decommissioning-Related Activities [Abstract]
Investment income						1
Long-term lease income						0
Unrecognized Tax Benefits Interest Income						0
AFUDC - equity		7				15
Other Income		12				15
Other, net		19				$ 31
Pepco Holdings LLC [Member] | Predecessor [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes			$ 78	86				253
Decommissioning-Related Activities [Abstract]
Investment income			0					0
Long-term lease income			0					0
Unrecognized Tax Benefits Interest Income			0					0
AFUDC - equity			7	2				11
Other Income			(11)	25				37
Other, net			$ (4)	27				48
Delmarva Power and Light Company [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes		5		4			14	14
Decommissioning-Related Activities [Abstract]
Investment income		0		0			0	0
Long-term lease income				0			0	0
Unrecognized Tax Benefits Interest Income		0					0	0
AFUDC - equity		1		0			3	1
Gain (Loss) on Disposition of Assets		4		0			4	0
Other Income		2		4			6	7
Other, net		3		4			9	8
Atlantic City Electric Company [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes		0		0			0	0
Decommissioning-Related Activities [Abstract]
Investment income		0		0			0	0
Long-term lease income				0			0	0
Unrecognized Tax Benefits Interest Income		0					1	1
AFUDC - equity		1		0			5	1
Gain (Loss) on Disposition of Assets		0					1
Other Income		1		1			2	2
Other, net		$ 2		$ 1			$ 8	$ 4
[1]	Includes investment income and realized gains and losses on sales of investments of the trust funds.
[2]	Includes the elimination of NDT fund activity for the Regulatory Agreement Units, including the elimination of net income taxes related to all NDT fund activity for those units. See Note 16 — Asset Retirement Obligations of the Exelon 2015 Form 10-K for additional information regarding the accounting for nuclear decommissioning.
[3]	In January 2015, in connection with Generation's $750 million issuance of five-year Senior Unsecured Notes, Exelon terminated certain floating-to-fixed interest rate swaps. As the original forecasted transactions were a series of future interest payments over a ten year period, a portion of the anticipated interest payments were probable not to occur. As a result, $26 million of anticipated payments were reclassified from AOCI to Other, net in Exelon's Consolidated Statement of Operations and Comprehensive Income.
[4]	Relates to the cash return on BGE’s rate stabilization deferral. See Note 3 — Regulatory Matters of the Exelon 2015 Form 10-K for additional information regarding the rate stabilization deferral.

Supplemental Financial Infor116

Supplemental Financial Information - Cash Flow (Details) - USD ($) $ in Millions		3 Months Ended			6 Months Ended	9 Months Ended
		Jun. 30, 2016	Mar. 23, 2016	Mar. 22, 2016	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015	Mar. 24, 2016	Dec. 31, 2015
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]					$ 2,490	$ 1,648
Regulatory assets	[1]					293	131
Amortization of intangible assets, net	[1]					38	39
Amortization of energy contract assets and liabilities	[2]					(7)	(20)
Nuclear fuel	[3]					862	841
Total depreciation, amortization and accretion						4,009	2,930
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense						458	476
Gain (loss) on equity method investments						15	3
Provision for uncollectible accounts						107	114
Stock-based compensation costs						88	102
Other Decommissioning Related Activity	[4]					(237)	(31)
Energy-related options	[5]					(20)	18
Amortization of regulatory asset related to debt costs						7	0
Amortization of rate stabilization deferral						62	60
Amortization of debt fair value adjustment						(9)	(34)
Discrete impacts from EIMA	[6]					(36)	101
Amortization of debt costs						26	43
Merger related commitments	[7],[8]					508
Inventory Write-down						74	7
InventoryLCMReservePeriodCharge						36	15
Restructuring Costs						130
Other						15	(18)
Total other noncash operating activities						1,224	856
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities						(537)	(322)
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Non cash Fair Value Adjustment for CENG						0	95
Payments to Acquire Businesses, Gross						6,896	28
Capital Expenditures Incurred but Not yet Paid						(338)	(59)
Capitalized Costs, Asset Retirement Costs					$ 476	476			$ 811
Asset Retirement Obligation, Accretion Expense	[9]					333	291
Capital Project [Member]
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Noncash or Part Noncash Acquisition, Fixed Assets Acquired						84
Nuclear Fuel Project [Member]
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Noncash or Part Noncash Acquisition, Fixed Assets Acquired							0
Exelon Generation Co L L C [Member]
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]					1,297	739
Amortization of intangible assets, net	[1]					32	35
Amortization of energy contract assets and liabilities	[2]					(7)	(19)
Nuclear fuel	[3]					862	841
Total depreciation, amortization and accretion						2,516	1,887
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense						163	200
Gain (loss) on equity method investments						16	4
Provision for uncollectible accounts						14	15
Stock-based compensation costs						0	0
Other Decommissioning Related Activity	[4]					(237)	(31)
Energy-related options	[5]					(20)	18
Amortization of regulatory asset related to debt costs						0	0
Amortization of rate stabilization deferral						0	0
Amortization of debt fair value adjustment						(9)	(9)
Discrete impacts from EIMA						0	0
Amortization of debt costs						12	12
Merger related commitments	[8]					3
Inventory Write-down						70	8
InventoryLCMReservePeriodCharge						36	15
Restructuring Costs						57
Other						24	(5)
Total other noncash operating activities						129	227
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities						(204)	(245)
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Non cash Fair Value Adjustment for CENG	[8]					119
Payments to Acquire Businesses, Gross						255	28
Capital Expenditures Incurred but Not yet Paid						(289)	(48)
Capitalized Costs, Asset Retirement Costs					476	476			811
Asset Retirement Obligation, Accretion Expense	[9]					332	291
Exelon Generation Co L L C [Member] | Capital Project [Member]
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Noncash or Part Noncash Acquisition, Fixed Assets Acquired						84
Exelon Generation Co L L C [Member] | Nuclear Fuel Project [Member]
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Noncash or Part Noncash Acquisition, Fixed Assets Acquired							0
Commonwealth Edison Co [Member]
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]					524	471
Regulatory assets	[1]					49	57
Total depreciation, amortization and accretion						574	528
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense						124	155
Gain (loss) on equity method investments						0	0
Provision for uncollectible accounts						31	46
Stock-based compensation costs						0	0
Other Decommissioning Related Activity						0	0
Energy-related options						0	0
Amortization of regulatory asset related to debt costs						3	0
Amortization of rate stabilization deferral						0	0
Amortization of debt fair value adjustment						0	0
Discrete impacts from EIMA	[6]					(36)	101
Amortization of debt costs						(3)	3
Inventory Write-down						4	0
InventoryLCMReservePeriodCharge							0
Other						(1)	7
Total other noncash operating activities						122	312
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities						104	34
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Non cash Fair Value Adjustment for CENG						0	0
Capital Expenditures Incurred but Not yet Paid						(42)	(62)
Capitalized Costs, Asset Retirement Costs					0	0			0
Asset Retirement Obligation, Accretion Expense	[9]					1
Commonwealth Edison Co [Member] | Indemnification Agreement [Member]
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Contribution of Property	[10]					157	5
PECO Energy Co [Member]
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]					181	179
Regulatory assets	[1]					20	19
Total depreciation, amortization and accretion						201	198
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense						25	29
Gain (loss) on equity method investments						0	0
Provision for uncollectible accounts						24	37
Stock-based compensation costs						0	0
Other Decommissioning Related Activity						0	0
Energy-related options						0	0
Amortization of regulatory asset related to debt costs						1	0
Amortization of rate stabilization deferral						0	0
Amortization of debt fair value adjustment						0	0
Discrete impacts from EIMA						0	0
Amortization of debt costs						2	2
Inventory Write-down						0	0
InventoryLCMReservePeriodCharge							0
Other						(3)	1
Total other noncash operating activities						49	69
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities						(49)	(16)
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Non cash Fair Value Adjustment for CENG						0	0
Capital Expenditures Incurred but Not yet Paid						(4)	23
Capitalized Costs, Asset Retirement Costs					0	0			0
Baltimore Gas and Electric Company [Member]
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]					223	216
Regulatory assets	[1]					84	55
Total depreciation, amortization and accretion						307	271
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense						50	49
Gain (loss) on equity method investments						0	0
Provision for uncollectible accounts						12	15
Stock-based compensation costs						0	0
Other Decommissioning Related Activity						0	0
Energy-related options						0	0
Amortization of regulatory asset related to debt costs						0	0
Amortization of rate stabilization deferral						62	60
Amortization of debt fair value adjustment						0	0
Discrete impacts from EIMA						0	0
Amortization of debt costs						3	2
Inventory Write-down						0	0
InventoryLCMReservePeriodCharge							0
Other						18	15
Total other noncash operating activities						109	111
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities						(2)	(28)
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Non cash Fair Value Adjustment for CENG						0	0
Capital Expenditures Incurred but Not yet Paid						17	(14)
Capitalized Costs, Asset Retirement Costs					0	0			0
Asset Retirement Obligation, Accretion Expense						0
PEPCO Holdings Inc [Member] | Predecessor [Member]
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Capitalized Costs, Asset Retirement Costs									0
Potomac Electric Power Company [Member]
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]					128	122
Regulatory assets	[1]					93	69
Amortization of intangible assets, net	[1]					0	0
Amortization of energy contract assets and liabilities	[2]					0	0
Nuclear fuel	[3]					0	0
Total depreciation, amortization and accretion						221	191
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense				$ 7		24	22
Gain (loss) on equity method investments						0	0
Provision for uncollectible accounts						15	15
Stock-based compensation costs						0	0
Other Decommissioning Related Activity						0	0
Energy-related options						0	0
Amortization of regulatory asset related to debt costs						2	2
Amortization of rate stabilization deferral						3	3
Amortization of debt fair value adjustment						0	0
Discrete impacts from EIMA						0	0
Amortization of debt costs						0	0
Merger related commitments	[8]					125
Inventory Write-down						1	0
Other						(2)	0
Total other noncash operating activities						168	42
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities						(83)	(94)
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Non cash Fair Value Adjustment for CENG						0	0
Capital Expenditures Incurred but Not yet Paid						15	1
Capitalized Costs, Asset Retirement Costs									0
Asset Retirement Obligation, Accretion Expense	[9]					0	0
Potomac Electric Power Company [Member] | Successor [Member]
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Payments to Acquire Businesses, Gross						33
Delmarva Power and Light Company [Member]
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]					82	76
Regulatory assets	[1]					38	37
Amortization of intangible assets, net	[1]					0	0
Amortization of energy contract assets and liabilities	[2]					0	0
Nuclear fuel	[3]					0	0
Asset retirement obligation accretion						5
Total depreciation, amortization and accretion						120	113
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense				4		13	11
Gain (loss) on equity method investments						0	0
Provision for uncollectible accounts						12	18
Stock-based compensation costs						0	0
Other Decommissioning Related Activity						0	0
Energy-related options						0	0
Amortization of regulatory asset related to debt costs						0	0
Amortization of rate stabilization deferral						3	1
Amortization of debt fair value adjustment						0	0
Discrete impacts from EIMA						0	0
Amortization of debt costs						0	0
Merger related commitments	[8]					73
Inventory Write-down						1	0
Other						(8)	1
Total other noncash operating activities						99	31
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities						(70)	(22)
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Non cash Fair Value Adjustment for CENG						0	0
Capital Expenditures Incurred but Not yet Paid						(10)	(2)
Capitalized Costs, Asset Retirement Costs									0
Asset Retirement Obligation, Accretion Expense	[9]					0	0
Asset Retirement Obligation, Revision of Estimate						(5)
Atlantic City Electric Company [Member]
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]					61	57
Regulatory assets	[1]					69	78
Amortization of intangible assets, net	[1]					0	0
Amortization of energy contract assets and liabilities	[2]					0	0
Nuclear fuel	[3]					0	0
Asset retirement obligation accretion						2
Total depreciation, amortization and accretion						130	135
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense				$ 3		11	11
Gain (loss) on equity method investments						0	0
Provision for uncollectible accounts						18	15
Stock-based compensation costs						0	0
Other Decommissioning Related Activity						0	0
Energy-related options						0	0
Amortization of regulatory asset related to debt costs						1	0
Amortization of rate stabilization deferral						0	0
Amortization of debt fair value adjustment						0	0
Discrete impacts from EIMA						0	0
Amortization of debt costs						0	0
Merger related commitments	[8]					110
Inventory Write-down						1	0
Other						(5)	1
Total other noncash operating activities						138	27
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities						(87)	8
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Non cash Fair Value Adjustment for CENG						0	0
Capital Expenditures Incurred but Not yet Paid						2	0
Capitalized Costs, Asset Retirement Costs									$ 0
Asset Retirement Obligation, Accretion Expense	[9]					0	0
Asset Retirement Obligation, Revision of Estimate						(2)
Pepco Holdings LLC [Member]
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Non cash Fair Value Adjustment for CENG			$ 0
Capital Expenditures Incurred but Not yet Paid			11
Pepco Holdings LLC [Member] | Predecessor [Member]
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]		94				292
Regulatory assets	[1]		58				182
Amortization of intangible assets, net	[1]		0				0
Amortization of energy contract assets and liabilities	[2]		0				0
Nuclear fuel	[3]		0				0
Total depreciation, amortization and accretion			152				474
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense			23				73
Gain (loss) on equity method investments			0
Provision for uncollectible accounts			16				49
Stock-based compensation costs			3				9
Other Decommissioning Related Activity			0				0
Energy-related options			0				0
Amortization of regulatory asset related to debt costs			1				4
Amortization of rate stabilization deferral			5				3
Amortization of debt fair value adjustment			0				0
Discrete impacts from EIMA			0				0
Amortization of debt costs			0				1
Inventory Write-down			1				1
Other			(3)				3
Total other noncash operating activities			46				143
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities			(9)				(112)
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Non cash Fair Value Adjustment for CENG							0
Capital Expenditures Incurred but Not yet Paid							3
Asset Retirement Obligation, Accretion Expense	[9]		$ 0				$ 0
Pepco Holdings LLC [Member] | Successor [Member]
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]				215
Regulatory assets	[1]				140
Amortization of intangible assets, net	[1]				0
Amortization of energy contract assets and liabilities	[2]				0
Nuclear fuel	[3]				0
Total depreciation, amortization and accretion					355
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense					58
Gain (loss) on equity method investments					0
Provision for uncollectible accounts					27
Stock-based compensation costs					0
Other Decommissioning Related Activity					0
Energy-related options					0
Amortization of regulatory asset related to debt costs					2
Amortization of rate stabilization deferral					0
Amortization of debt fair value adjustment					0
Discrete impacts from EIMA					0
Amortization of debt costs					0
Merger related commitments	[8]				308
Inventory Write-down					0
Restructuring Costs					(53)
Other					(7)
Total other noncash operating activities					441
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities					(248)
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Non cash Fair Value Adjustment for CENG					129
Business Combination, Contingent Consideration, Liability, Noncurrent								$ 53
Capital Expenditures Incurred but Not yet Paid					(5)
Asset Retirement Obligation, Accretion Expense	[9]				0
Pepco Holdings LLC [Member] | Successor [Member]
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Payments to Acquire Businesses, Gross		$ 33			62
Deferred Compensation, Share-based Payments [Member] | Pepco Holdings LLC [Member]
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Payments to Acquire Businesses, Gross						$ 29
Deferred Compensation, Share-based Payments [Member] | Pepco Holdings LLC [Member] | Successor [Member]
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Payments to Acquire Businesses, Gross					$ 29
[1]	(a)Included in Depreciation and amortization on the Registrants' Consolidated Statements of Operations and Comprehensive Income.
[2]	(b)Included in Operating revenues or Purchased power and fuel expense on the Registrants’ Consolidated Statements of Operations and Comprehensive Income
[3]	Included in Purchased power and fuel expense on the Registrants’ Consolidated Statements of Operations and Comprehensive Income
[4]	Includes the elimination of NDT fund activity for the Regulatory Agreement Units, including the elimination of operating revenues, ARO accretion, ARC amortization, investment income and income taxes related to all NDT fund activity for these units. See Note 16 - Asset Retirement Obligations of the Exelon 2015 Form 10-K for additional information regarding the accounting for nuclear decommissioning
[5]	Includes option premiums reclassified to realized at the settlement of the underlying contracts and recorded
[6]	Reflects the change in distribution rates pursuant to EIMA, which allows for the recovery of costs by a utility through a pre-established performance-based formula rate tariff. See Note 5 — Regulatory Matters for more information
[7]	(e)Excludes $5 million of forgiveness of Accounts receivable related to merger commitments recorded in connection with the PHI Merger, the balance is included within Provision for uncollectible accounts.
[8]	See Note 4 — Mergers, Acquisitions and Dispositions for additional information related to the merger with PHI.
[9]	Included in Operating and maintenance expense on the Registrants’ Consolidated Statements of Operations and Comprehensive Income
[10]	See Note 11— Income Taxes for discussion of the like-kind exchange tax position

Supplemental Financial Infor117

Supplemental Financial Information - Balance Sheet (Details) - USD ($) $ in Millions	Sep. 30, 2016		Dec. 31, 2015
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	$ 18,354	[1]	$ 16,375	[2]
Accounts receivable, net
Allowance for uncollectible accounts	330		284
Exelon Generation Co L L C [Member]
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	10,004	[1]	8,639	[2]
Accounts receivable, net
Allowance for uncollectible accounts	85		77
Exelon Generation Co L L C [Member] | Nuclear Fuel [Member]
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	3,198		2,861
Commonwealth Edison Co [Member]
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	3,841		3,710
Accounts receivable, net
Allowance for uncollectible accounts	82		75
PECO Energy Co [Member]
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	3,213		3,101
Accounts receivable, net
Allowance for uncollectible accounts	78		83
Baltimore Gas and Electric Company [Member]
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	3,198		3,016
Accounts receivable, net
Allowance for uncollectible accounts	39		49
Pepco Holdings LLC [Member] | Predecessor [Member]
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation			5,341
Accounts receivable, net
Allowance for uncollectible accounts			56
Pepco Holdings LLC [Member] | Successor [Member]
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	146
Accounts receivable, net
Allowance for uncollectible accounts	46
Potomac Electric Power Company [Member]
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	3,026		2,929
Accounts receivable, net
Allowance for uncollectible accounts	15		17
Delmarva Power and Light Company [Member]
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	1,171		1,139
Accounts receivable, net
Allowance for uncollectible accounts	14		17
Atlantic City Electric Company [Member]
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	1,008		968
Accounts receivable, net
Allowance for uncollectible accounts	$ 17		$ 17
[1]	Includes accumulated amortization of nuclear fuel in the reactor core of $3,198 million
[2]	Includes accumulated amortization of nuclear fuel in the reactor core of $2,861 million

Supplemental Financial Infor118

Supplemental Financial Information Supplemental Financial Information - Utility Taxes (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended	9 Months Ended
	Sep. 30, 2016	Mar. 23, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes	$ 255		$ 151		$ 624	$ 430
Exelon Generation Co L L C [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes	35		28		90	79
Commonwealth Edison Co [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes	67		63		186	180
PECO Energy Co [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes	40		37		106	104
Baltimore Gas and Electric Company [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes	21		23		66	67
Pepco Holdings LLC [Member] | Predecessor [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes		$ 78	86			253
Pepco Holdings LLC [Member] | Successor [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes	92			$ 176
Potomac Electric Power Company [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes	87		82		240	239
Delmarva Power and Light Company [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes	5		4		14	14
Atlantic City Electric Company [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes	$ 0		$ 0		$ 0	$ 0

Segment Information - Narrative

Segment Information - Narrative (Details)	9 Months Ended
	Sep. 30, 2016Reportable_segment
Exelon Generation Co L L C [Member]
Segment Reporting Information [Line Items]
Number of reportable segments	6

Segment Information - Reconcili

Segment Information - Reconciliation to Consolidated Financial Statements (Details) - USD ($) $ in Millions	3 Months Ended						6 Months Ended	9 Months Ended
	Sep. 30, 2016		Jun. 30, 2016	Mar. 23, 2016	Sep. 30, 2015		Sep. 30, 2016	Sep. 30, 2016		Sep. 30, 2015		Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues	$ 9,002				$ 7,401			$ 23,486		$ 22,746
Competitive Energy Revenue	3,823				4,095			10,559		11,796
Electric Revenue	4,330				2,721			10,461		7,564
Other Operating Income	386				122			169		581
Revenue from Purchased Oil and Gas	326				347			1,515		1,901
Operating revenues from affiliates	1				2
Net income (loss)	526				587			956		1,959
Assets	114,535						$ 114,535	114,535				$ 95,384
Gas Domestic Regulated Revenue	137				116			781		904
Sales Revenue, Services, Other	0				0			1		0
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Competitive Energy Revenue					0			0		0
Electric Revenue	0				0			0		0
Other Operating Income					0			0		0
Revenue from Purchased Oil and Gas					0			0		0
Net income (loss)	(125)				(36)			(340)		(96)
Assets	9,883						9,883	9,883				15,389
Gas Domestic Regulated Revenue	0				0			0		0
Sales Revenue, Services, Other	362				348			1,166		1,007
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Competitive Energy Revenue	(499)				(204)			(1,118)		(564)
Electric Revenue	(8)				(1)			(24)		(3)
Other Operating Income	(1)				0			(2)		1
Revenue from Purchased Oil and Gas	0				0			0		0
Operating revenues from affiliates	(885)				(555)			3		3
Net income (loss)	(1)				(2)			(3)		(3)
Assets	(11,897)						(11,897)	(11,897)				(11,728)
Gas Domestic Regulated Revenue	(5)				(3)			(10)		(12)
Sales Revenue, Services, Other	(373)				(348)			(1,199)		(1,007)
Intersegment Eliminations [Member] | Successor [Member]
Segment Reporting Information [Line Items]
Electric Revenue	(4)						(9)
Operating revenues from affiliates	(4)						(9)
Net income (loss)	11						34
Assets	(4,743)						(4,743)	(4,743)
Gas Domestic Regulated Revenue							0
Sales Revenue, Services, Other	0						0
Intersegment Eliminations [Member] | Predecessor [Member]
Segment Reporting Information [Line Items]
Electric Revenue				$ (4)	0					0
Operating revenues from affiliates				(4)	(3)					(10)
Net income (loss)				0	0					0
Assets												(5,238)
Gas Domestic Regulated Revenue				0	0					0
Sales Revenue, Services, Other				0	0					0
Exelon Generation Co L L C [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Competitive Energy Revenue	4,322				4,299			11,677		12,360
Electric Revenue	0				0			0		0
Other Operating Income	387				122			171		580
Revenue from Purchased Oil and Gas	326				347			1,515		1,901
Net income (loss)	271				332			556		1,208
Assets	47,568						47,568	47,568				46,529
Gas Domestic Regulated Revenue	0				0			0		0
Sales Revenue, Services, Other	0				0			0		0
Exelon Generation Co L L C [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates	500				205			1,121		567
Generation Midwest [Member]
Segment Reporting Information [Line Items]
Revenues	1,164				1,151			3,343		3,633
Generation Midwest [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	1,163	[1]			1,152	[1]		3,330	[2]	3,634	[2]
Generation Midwest [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	1				(1)			13		(1)
Commonwealth Edison Co [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Competitive Energy Revenue	0				0			0		0
Electric Revenue	1,497				1,376			4,031		3,709
Other Operating Income	0				0			0		0
Revenue from Purchased Oil and Gas	0				0			0		0
Net income (loss)	37				149			297		339
Assets	28,020						28,020	28,020				26,532
Gas Domestic Regulated Revenue	0				0			0		0
Sales Revenue, Services, Other	0				0			0		0
Commonwealth Edison Co [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates	4				1			12		3
PECO Energy Co [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Competitive Energy Revenue	0				0			0		0
Electric Revenue	740				691			1,971		1,950
Other Operating Income	0				0			0		0
Revenue from Purchased Oil and Gas	0				0			0		0
Net income (loss)	122				90			346		299
Assets	11,041						11,041	11,041				10,367
Gas Domestic Regulated Revenue	48				49			322		436
Sales Revenue, Services, Other	0				0			0		0
PECO Energy Co [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates	2				1			5		1
Baltimore Gas and Electric Company [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Competitive Energy Revenue	0				0			0		0
Electric Revenue	735				655			1,998		1,908
Other Operating Income	0				0			0		0
Revenue from Purchased Oil and Gas	0				0			0		0
Net income (loss)	56				54			191		212
Assets	8,857						8,857	8,857				8,295
Gas Domestic Regulated Revenue	77				70			423		480
Sales Revenue, Services, Other	0				0			0		0
Baltimore Gas and Electric Company [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates	7				3			16		10
Corporate and Other [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates								1,166		1,003
Pepco Holdings LLC [Member] | Successor [Member]
Segment Reporting Information [Line Items]
Electric Revenue	1,366						2,485
Net income (loss)	166						(91)
Gas Domestic Regulated Revenue	17						46
Sales Revenue, Services, Other	11						34
Pepco Holdings LLC [Member] | Predecessor [Member]
Segment Reporting Information [Line Items]
Electric Revenue				1,096	1,317					3,680
Net income (loss)				19
Gas Domestic Regulated Revenue				57	19					129
Sales Revenue, Services, Other				0	0					0
Pepco Holdings LLC [Member] | Corporate, Non-Segment [Member] | Successor [Member]
Segment Reporting Information [Line Items]
Electric Revenue	0						3
Operating revenues from affiliates	11						35
Net income (loss)	(15)						(16)
Assets	11,057						11,057	11,057
Gas Domestic Regulated Revenue	0						0
Sales Revenue, Services, Other	11						34
Pepco Holdings LLC [Member] | Corporate, Non-Segment [Member] | Predecessor [Member]
Segment Reporting Information [Line Items]
Electric Revenue				42	44					161
Operating revenues from affiliates				0	0					0
Net income (loss)				(44)	(6)					(23)
Assets												7,162
Gas Domestic Regulated Revenue				1	0					0
Sales Revenue, Services, Other				0	0					0
Pepco Holdings LLC [Member] | Operating Segments [Member] | Successor [Member]
Segment Reporting Information [Line Items]
Competitive Energy Revenue	0							0		0
Electric Revenue	1,366				0			2,485		0
Other Operating Income	0							0		0
Revenue from Purchased Oil and Gas	0							0		0
Operating revenues from affiliates	11						34
Net income (loss)	166				0			(91)		0
Assets	21,063						21,063	21,063				0
Gas Domestic Regulated Revenue	17				0			46		0
Sales Revenue, Services, Other	11				0			34		0
Pepco Holdings LLC [Member] | Operating Segments [Member] | Predecessor [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates				0	0					0
Net income (loss)					91					197
Assets												16,188
Pepco Holdings LLC [Member] | Intersegment Eliminations [Member] | Successor [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates	11				0			34		0
Corporate, Non-Segment [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates	362				347
Segment Elimination [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates								(2,351)		(1,581)
Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Revenues	5,035				4,768			13,363		14,841
Generation Total Consolidated Group [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	5,035	[1]			4,768	[1]		13,363	[2]	14,841	[2]
Generation Total Consolidated Group [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	0				0			0		0
Potomac Electric Power Company [Member] | Operating Segments [Member] | Successor [Member]
Segment Reporting Information [Line Items]
Electric Revenue	635		$ 1,184
Operating revenues from affiliates	1						2
Net income (loss)	79						(12)
Assets	7,219						7,219	7,219
Gas Domestic Regulated Revenue	0		0
Sales Revenue, Services, Other	0		0
Potomac Electric Power Company [Member] | Operating Segments [Member] | Predecessor [Member]
Segment Reporting Information [Line Items]
Electric Revenue				511	592					1,641
Operating revenues from affiliates				1	1					4
Net income (loss)				32	60					128
Assets												6,908
Gas Domestic Regulated Revenue				0	0					0
Sales Revenue, Services, Other				0	0					0
Delmarva Power and Light Company [Member] | Operating Segments [Member] | Successor [Member]
Segment Reporting Information [Line Items]
Electric Revenue	314		593
Operating revenues from affiliates	2						4
Net income (loss)	44						(42)
Assets	4,023						4,023	4,023
Gas Domestic Regulated Revenue	17		46
Sales Revenue, Services, Other	0		0
Delmarva Power and Light Company [Member] | Operating Segments [Member] | Predecessor [Member]
Segment Reporting Information [Line Items]
Electric Revenue				279	295					875
Operating revenues from affiliates				2	1					4
Net income (loss)				26	15					55
Assets												3,969
Gas Domestic Regulated Revenue				56	19					129
Sales Revenue, Services, Other				0	0					0
Atlantic City Electric Company [Member] | Operating Segments [Member] | Successor [Member]
Segment Reporting Information [Line Items]
Electric Revenue	421		714
Operating revenues from affiliates	1						2
Net income (loss)	47						(55)
Assets	3,507						$ 3,507	3,507
Gas Domestic Regulated Revenue	0		0
Sales Revenue, Services, Other	0		$ 0
Atlantic City Electric Company [Member] | Operating Segments [Member] | Predecessor [Member]
Segment Reporting Information [Line Items]
Electric Revenue				268	386					1,003
Operating revenues from affiliates				1	1					2
Net income (loss)				5	22					37
Assets												$ 3,387
Gas Domestic Regulated Revenue				0	0					0
Sales Revenue, Services, Other				$ 0	0					0
PECO Energy Co Affiliate [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues								234		173
PECO Energy Co Affiliate [Member] | Generation Midwest [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	91				61
Baltimore Gas And Electric Company Affiliate [Member] | Generation Midwest [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	183				141			489		376
Commonwealth Edison Co Affiliate [Member] | Generation Midwest [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	20				$ 2			$ 38		$ 17
PotomacElectricPowerCompanyAffiliate [Member] | Generation Midwest [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	128
PotomacElectricPowerCompanyAffiliate [Member] | Generation Midwest [Member] | Operating Segments [Member] | Successor [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates	223
DelmarvaPowerandLightCompanyAffiliate [Member] | Generation Midwest [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	63
DelmarvaPowerandLightCompanyAffiliate [Member] | Generation Midwest [Member] | Operating Segments [Member] | Successor [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates	109
AtlanticCityElectricCompanyAffiliate [Member] | Generation Midwest [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	15
AtlanticCityElectricCompanyAffiliate [Member] | Generation Midwest [Member] | Operating Segments [Member] | Successor [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates	$ 28
[1]	Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 Revenuesfrom externalcustomers(a)IntersegmentrevenuesTotalRevenuesRevenuesfrom externalcustomers(a)(c)Intersegmentrevenues(c)TotalRevenues(c)Mid-Atlantic$1,813 $(13) $1,800 $1,640 $(8) $1,632Midwest1,163 1 1,164 1,152 (1) 1,151New England455 (4) 451 520 — 520New York331 (8) 323 254 (4) 250ERCOT289 6 295 317 (1) 316Other Power Regions271 (33) 238 416 (40) 376Total Revenues for Reportable Segments4,322 (51) 4,271 4,299 (54) 4,245Other(b)713 51 764 469 54 523Total Generation Consolidated Operating Revenues$5,035 $— $5,035 $4,768 $— $4,768
[2]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOjk5ZDczZmJiZmVlMzQwYjliY2U1YWJiOTI2MjM3MWNhfFRleHRTZWxlY3Rpb246NDNBNkVDOEMwNDMyNUYwOEEwRjQ1MDc1RjM2NzgxOTMM}

Segment Information - Generatio

Segment Information - Generation Total Revenues (Details) - USD ($) $ in Millions	3 Months Ended					9 Months Ended
	Sep. 30, 2016		Jun. 30, 2016	Sep. 30, 2015		Sep. 30, 2016		Sep. 30, 2015
Segment Reporting Information [Line Items]
Revenues	$ (9,002)			$ (7,401)		$ (23,486)		$ (22,746)
Revenue from Related Parties	(1)			(2)
Net income (loss)	526			587		956		1,959
Derivative, Loss on Derivative			$ (3)
Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Revenues	(1,800)			(1,632)		(4,736)		(4,491)
Generation New England [Member]
Segment Reporting Information [Line Items]
Revenues	(451)			(520)		(1,272)		(1,746)
Generation New York [Member]
Segment Reporting Information [Line Items]
Revenues	(323)			(250)		(873)		(778)
Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Revenues	(295)			(316)		(665)		(687)
Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Revenues	(238)			(376)		(686)		(880)
Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Revenues	(4,271)			(4,245)		(11,575)		(12,215)
Generation Reportable Segments Total [Member] | Scenario, Adjustment [Member]
Segment Reporting Information [Line Items]
Revenues				(54)				(144)
Revenue from Related Parties				(54)				(144)
Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues	(764)			(523)		(1,788)		(2,626)
Amortization of intangible assets related to commodity contracts	(21)			(3)		(10)		19
Derivative, Gain on Derivative	(187)							171
Derivative, Loss on Derivative				(7)		(366)
Generation All Other Segments [Member] | Scenario, Adjustment [Member]
Segment Reporting Information [Line Items]
Revenues				(54)				144
Revenue from Related Parties				(54)				(144)
Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Revenues	(5,035)			(4,768)		(13,363)		(14,841)
Operating Segments [Member] | Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Revenues	(1,813)	[1]		(1,640)	[1]	(4,776)	[2],[3]	(4,560)	[2],[3]
Operating Segments [Member] | Generation New England [Member]
Segment Reporting Information [Line Items]
Revenues	(455)	[1]		(520)	[1]	(1,278)	[3]	(1,752)	[3]
Operating Segments [Member] | Generation New York [Member]
Segment Reporting Information [Line Items]
Revenues	(331)	[1]		(254)	[1]	(906)	[2],[3]	(783)	[2],[3]
Operating Segments [Member] | Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Revenues	(289)	[1]		(317)	[1]	(659)	[3]	(691)	[3]
Operating Segments [Member] | Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Revenues	(271)	[1],[4]		(416)	[1],[4]	(728)	[3],[5]	(940)	[3],[5]
Operating Segments [Member] | Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Revenues	(4,322)	[1]		(4,299)	[1]	(11,677)	[3]	(12,360)	[3]
Operating Segments [Member] | Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Revenues	(5,035)	[1]		(4,768)	[1]	(13,363)	[3]	(14,841)	[3]
Operating Segments [Member] | Exelon Generation Co L L C [Member]
Segment Reporting Information [Line Items]
Net income (loss)	271			332		556		1,208
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Net income (loss)	(125)			(36)		(340)		(96)
Corporate, Non-Segment [Member] | Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues	(713)	[1],[6]		(469)	[1],[6]	(1,686)	[3],[7]	(2,481)	[3],[7]
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	885			555		(3)		(3)
Net income (loss)	(1)			(2)		(3)		(3)
Intersegment Eliminations [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties						(1,166)		(1,003)
Intersegment Eliminations [Member] | Segment Elimination [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties						2,351		1,581
Intersegment Eliminations [Member] | Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Revenues	13			8		40	[2]	69	[2]
Intersegment Eliminations [Member] | Generation New England [Member]
Segment Reporting Information [Line Items]
Revenues	4			0		6		6
Intersegment Eliminations [Member] | Generation New York [Member]
Segment Reporting Information [Line Items]
Revenues	8			4		33	[2]	5	[2]
Intersegment Eliminations [Member] | Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Revenues	(6)			1		(6)		4
Intersegment Eliminations [Member] | Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Revenues	33	[4]		40	[4]	42	[5]	60	[5]
Intersegment Eliminations [Member] | Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Revenues	51			54		102		145
Intersegment Eliminations [Member] | Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues	(51)	[6]		(54)	[6]	(102)	[7]	(145)	[7]
Intersegment Eliminations [Member] | Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Revenues	0			0		0		0
Intersegment Eliminations [Member] | Exelon Generation Co L L C [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	$ (500)			$ (205)		$ (1,121)		$ (567)
[1]	Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 Revenuesfrom externalcustomers(a)IntersegmentrevenuesTotalRevenuesRevenuesfrom externalcustomers(a)(c)Intersegmentrevenues(c)TotalRevenues(c)Mid-Atlantic$1,813 $(13) $1,800 $1,640 $(8) $1,632Midwest1,163 1 1,164 1,152 (1) 1,151New England455 (4) 451 520 — 520New York331 (8) 323 254 (4) 250ERCOT289 6 295 317 (1) 316Other Power Regions271 (33) 238 416 (40) 376Total Revenues for Reportable Segments4,322 (51) 4,271 4,299 (54) 4,245Other(b)713 51 764 469 54 523Total Generation Consolidated Operating Revenues$5,035 $— $5,035 $4,768 $— $4,768
[2]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOjk5ZDczZmJiZmVlMzQwYjliY2U1YWJiOTI2MjM3MWNhfFRleHRTZWxlY3Rpb246MTdGRTY4QTU5RDRENTQxRUI0NzhEODYyMUI4Q0UwRDQM}
[3]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOjk5ZDczZmJiZmVlMzQwYjliY2U1YWJiOTI2MjM3MWNhfFRleHRTZWxlY3Rpb246NDNBNkVDOEMwNDMyNUYwOEEwRjQ1MDc1RjM2NzgxOTMM}
[4]	Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 Revenuesfrom externalcustomers(a)IntersegmentrevenuesTotalRevenuesRevenuesfrom externalcustomers(a)(c)Intersegmentrevenues(c)TotalRevenues(c)Mid-Atlantic$1,813 $(13) $1,800 $1,640 $(8) $1,632Midwest1,163 1 1,164 1,152 (1) 1,151New England455 (4) 451 520 — 520New York331 (8) 323 254 (4) 250ERCOT289 6 295 317 (1) 316Other Power Regions271 (33) 238 416 (40) 376Total Revenues for Reportable Segments4,322 (51) 4,271 4,299 (54) 4,245Other(b)713 51 764 469 54 523Total Generation Consolidated Operating Revenues$5,035 $— $5,035 $4,768 $— $4,768
[5]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOjk5ZDczZmJiZmVlMzQwYjliY2U1YWJiOTI2MjM3MWNhfFRleHRTZWxlY3Rpb246NUY3NkI2RTJCMDAyNTZBQUJFNUZBOTU5MTExODhGMDgM}
[6]	Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 Revenuesfrom externalcustomers(a)IntersegmentrevenuesTotalRevenuesRevenuesfrom externalcustomers(a)(c)Intersegmentrevenues(c)TotalRevenues(c)Mid-Atlantic$1,813 $(13) $1,800 $1,640 $(8) $1,632Midwest1,163 1 1,164 1,152 (1) 1,151New England455 (4) 451 520 — 520New York331 (8) 323 254 (4) 250ERCOT289 6 295 317 (1) 316Other Power Regions271 (33) 238 416 (40) 376Total Revenues for Reportable Segments4,322 (51) 4,271 4,299 (54) 4,245Other(b)713 51 764 469 54 523Total Generation Consolidated Operating Revenues$5,035 $— $5,035 $4,768 $— $4,768
[7]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOjk5ZDczZmJiZmVlMzQwYjliY2U1YWJiOTI2MjM3MWNhfFRleHRTZWxlY3Rpb246QjRCNEYyM0QzNjhCNTEwRTlDNjBCQ0NFMEYxMzZERTAM}

Segment Information - Genera122

Segment Information - Generation Total Revenues Net of Purchased Power and Fuel Expense (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2016		Sep. 30, 2015		Sep. 30, 2016		Sep. 30, 2015
Segment Reporting Information [Line Items]
Revenues		$ 9,002		$ 7,401		$ 23,486		$ 22,746
Unrealized Gain (Loss) on Derivatives						(100)		363
Nuclear Fuel Amortization	[1]					862		841
Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel		2,446		2,249		6,754		7,041
Revenues		5,035		4,768		13,363		14,841
Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel		887		997		2,556		2,677
Revenues		1,800		1,632		4,736		4,491
Generation Midwest [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel		781		756		2,229		2,205
Revenues		1,164		1,151		3,343		3,633
Generation New England [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel		160		133		350		379
Revenues		451		520		1,272		1,746
Generation New York [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel		194		170		592		502
Revenues		323		250		873		778
Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel		93		111		231		235
Revenues		295		316		665		687
Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel		77		83		253		193
Revenues		238		376		686		880
Other Segments [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel				(1)
Other Segments [Member] | Scenario, Adjustment [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel				13				(6)
Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Amortization Of Intangible Assets Related To Commodity Contracts For Revenue Net Purchased Power And Fuel		(22)		(4)		(15)		20
Segment Reporting Information Revenue Net of Purchase Power And Fuel		254				543		850
Revenues		764		523		1,788		2,626
Derivative, Gain on Derivative		(187)						171
Unrealized Gain (Loss) on Derivatives		88		139		(113)		258
Nuclear Fuel Amortization		(28)				(38)
Generation All Other Segments [Member] | Scenario, Adjustment [Member]
Segment Reporting Information [Line Items]
Intersegment RNF				(12)				(22)
Segment Reporting Information Revenue Net of Purchase Power And Fuel								28
Revenues				54				(144)
Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel		2,192		2,250		6,211		6,191
Revenues		4,271		4,245		11,575		12,215
Generation Reportable Segments Total [Member] | Scenario, Adjustment [Member]
Segment Reporting Information [Line Items]
Intersegment RNF				12				22
Segment Reporting Information Revenue Net of Purchase Power And Fuel								6
Revenues				54				144
Intersegment Eliminations [Member] | Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Intersegment RNF		0		0		0		0
Revenues		0		0		0		0
Intersegment Eliminations [Member] | Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Intersegment RNF		6		18		15		(2)
Revenues		(13)		(8)		(40)	[2]	(69)	[2]
Intersegment Eliminations [Member] | Generation Midwest [Member]
Segment Reporting Information [Line Items]
Intersegment RNF		(1)		(4)		4		(15)
Revenues		1		(1)		13		(1)
Intersegment Eliminations [Member] | Generation New England [Member]
Segment Reporting Information [Line Items]
Intersegment RNF		(10)		(15)		(23)		(46)
Revenues		(4)		0		(6)		(6)
Intersegment Eliminations [Member] | Generation New York [Member]
Segment Reporting Information [Line Items]
Intersegment RNF		(1)		13		(15)		40
Revenues		(8)		(4)		(33)	[2]	(5)	[2]
Intersegment Eliminations [Member] | Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Intersegment RNF		(51)		(55)		(104)		(109)
Revenues		6		(1)		6		(4)
Intersegment Eliminations [Member] | Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Intersegment RNF		(66)		(71)		(104)		(148)
Revenues		(33)	[3]	(40)	[3]	(42)	[4]	(60)	[4]
Intersegment Eliminations [Member] | Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Intersegment RNF		123		114		227		280
Revenues		51	[5]	54	[5]	102	[6]	145	[6]
Intersegment Eliminations [Member] | Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Intersegment RNF		(123)		(114)		(227)		(280)
Revenues		(51)		(54)		(102)		(145)
Operating Segments [Member] | Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net Of Purchase Power And Fuel From External Customers		2,446		2,249		6,754		7,041
Revenues		5,035	[7]	4,768	[7]	13,363	[8]	14,841	[8]
Operating Segments [Member] | Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net Of Purchase Power And Fuel From External Customers		881		979		2,541		2,679
Revenues		1,813	[7]	1,640	[7]	4,776	[2],[8]	4,560	[2],[8]
Operating Segments [Member] | Generation Midwest [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net Of Purchase Power And Fuel From External Customers		782		760		2,225		2,220
Revenues		1,163	[7]	1,152	[7]	3,330	[8]	3,634	[8]
Operating Segments [Member] | Generation New England [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net Of Purchase Power And Fuel From External Customers		170		148		373		425
Revenues		455	[7]	520	[7]	1,278	[8]	1,752	[8]
Operating Segments [Member] | Generation New York [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net Of Purchase Power And Fuel From External Customers		195		157		607		462
Revenues		331	[7]	254	[7]	906	[2],[8]	783	[2],[8]
Operating Segments [Member] | Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net Of Purchase Power And Fuel From External Customers		144		166		335		344
Revenues		289	[7]	317	[7]	659	[8]	691	[8]
Operating Segments [Member] | Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net Of Purchase Power And Fuel From External Customers		143		154		357		341
Revenues		271	[3],[7]	416	[3],[7]	728	[4],[8]	940	[4],[8]
Operating Segments [Member] | Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net Of Purchase Power And Fuel From External Customers		131		(115)		316		570
Operating Segments [Member] | Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net Of Purchase Power And Fuel From External Customers		2,315		2,364		6,438		6,471
Revenues		$ 4,322	[7]	$ 4,299	[7]	$ 11,677	[8]	$ 12,360	[8]
[1]	Included in Purchased power and fuel expense on the Registrants’ Consolidated Statements of Operations and Comprehensive Income
[2]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOjk5ZDczZmJiZmVlMzQwYjliY2U1YWJiOTI2MjM3MWNhfFRleHRTZWxlY3Rpb246MTdGRTY4QTU5RDRENTQxRUI0NzhEODYyMUI4Q0UwRDQM}
[3]	Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 Revenuesfrom externalcustomers(a)IntersegmentrevenuesTotalRevenuesRevenuesfrom externalcustomers(a)(c)Intersegmentrevenues(c)TotalRevenues(c)Mid-Atlantic$1,813 $(13) $1,800 $1,640 $(8) $1,632Midwest1,163 1 1,164 1,152 (1) 1,151New England455 (4) 451 520 — 520New York331 (8) 323 254 (4) 250ERCOT289 6 295 317 (1) 316Other Power Regions271 (33) 238 416 (40) 376Total Revenues for Reportable Segments4,322 (51) 4,271 4,299 (54) 4,245Other(b)713 51 764 469 54 523Total Generation Consolidated Operating Revenues$5,035 $— $5,035 $4,768 $— $4,768
[4]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOjk5ZDczZmJiZmVlMzQwYjliY2U1YWJiOTI2MjM3MWNhfFRleHRTZWxlY3Rpb246NUY3NkI2RTJCMDAyNTZBQUJFNUZBOTU5MTExODhGMDgM}
[5]	Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 Revenuesfrom externalcustomers(a)IntersegmentrevenuesTotalRevenuesRevenuesfrom externalcustomers(a)(c)Intersegmentrevenues(c)TotalRevenues(c)Mid-Atlantic$1,813 $(13) $1,800 $1,640 $(8) $1,632Midwest1,163 1 1,164 1,152 (1) 1,151New England455 (4) 451 520 — 520New York331 (8) 323 254 (4) 250ERCOT289 6 295 317 (1) 316Other Power Regions271 (33) 238 416 (40) 376Total Revenues for Reportable Segments4,322 (51) 4,271 4,299 (54) 4,245Other(b)713 51 764 469 54 523Total Generation Consolidated Operating Revenues$5,035 $— $5,035 $4,768 $— $4,768
[6]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOjk5ZDczZmJiZmVlMzQwYjliY2U1YWJiOTI2MjM3MWNhfFRleHRTZWxlY3Rpb246QjRCNEYyM0QzNjhCNTEwRTlDNjBCQ0NFMEYxMzZERTAM}
[7]	Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 Revenuesfrom externalcustomers(a)IntersegmentrevenuesTotalRevenuesRevenuesfrom externalcustomers(a)(c)Intersegmentrevenues(c)TotalRevenues(c)Mid-Atlantic$1,813 $(13) $1,800 $1,640 $(8) $1,632Midwest1,163 1 1,164 1,152 (1) 1,151New England455 (4) 451 520 — 520New York331 (8) 323 254 (4) 250ERCOT289 6 295 317 (1) 316Other Power Regions271 (33) 238 416 (40) 376Total Revenues for Reportable Segments4,322 (51) 4,271 4,299 (54) 4,245Other(b)713 51 764 469 54 523Total Generation Consolidated Operating Revenues$5,035 $— $5,035 $4,768 $— $4,768
[8]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOjk5ZDczZmJiZmVlMzQwYjliY2U1YWJiOTI2MjM3MWNhfFRleHRTZWxlY3Rpb246NDNBNkVDOEMwNDMyNUYwOEEwRjQ1MDc1RjM2NzgxOTMM}

Uncategorized Items - exc-20160

Label	Element	Value
Pepco Holdings LLC [Member] | Predecessor [Member]
Distribution to members	exc_DistributionToMembers	$ 0
Payments for (Proceeds from) Other Investing Activities	us-gaap_PaymentsForProceedsFromOtherInvestingActivities	5,000,000
Unrealized Gain (Loss) on Derivatives	us-gaap_UnrealizedGainLossOnDerivatives	(18,000,000)
Change Receivables Payables From Affiliates	exc_ChangeReceivablesPayablesFromAffiliates	0
Increase (Decrease) in Receivables	us-gaap_IncreaseDecreaseInReceivables	28,000,000
Proceeds from Issuance of Preferred Stock and Preference Stock	us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock	0
Proceeds from (Payments for) Other Financing Activities	us-gaap_ProceedsFromPaymentsForOtherFinancingActivities	2,000,000
Payments to Acquire Marketable Securities	us-gaap_PaymentsToAcquireMarketableSecurities	68,000,000
Increase (Decrease) in Accounts Payable and Accrued Liabilities	us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	42,000,000
Proceeds from Issuance of Long-term Debt	us-gaap_ProceedsFromIssuanceOfLongTermDebt	0
Proceeds from (Repayments of) Short-term Debt, Maturing in Three Months or Less	us-gaap_ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	(121,000,000)
Pension and Other Postretirement Benefit Contributions	us-gaap_PensionAndOtherPostretirementBenefitContributions	4,000,000
Deferred Income Taxes and Tax Credits	us-gaap_DeferredIncomeTaxesAndTaxCredits	19,000,000
Payments of Ordinary Dividends, Common Stock	us-gaap_PaymentsOfDividendsCommonStock	0
Payments to Acquire Property, Plant, and Equipment	us-gaap_PaymentsToAcquirePropertyPlantAndEquipment	273,000,000
Increase (Decrease) Cash Collateral from Counterparties	us-gaap_IncreaseDecreaseCashCollateralFromCounterparties	1,000,000
Proceeds from Short-term Debt, Maturing in More than Three Months	us-gaap_ProceedsFromShortTermDebtMaturingInMoreThanThreeMonths	500,000,000
Increase (Decrease) in Income Taxes Payable	us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable	12,000,000
Change in Exelon intercompany money pool borrowings	exc_ChangeInExelonIntercompanyMoneyPoolBorrowings	0
Increase (Decrease) in Restricted Cash	us-gaap_IncreaseDecreaseInRestrictedCash	(3,000,000)
Repayments of Long-term Debt	us-gaap_RepaymentsOfLongTermDebt	11,000,000
Other Noncash Income (Expense)	us-gaap_OtherNoncashIncomeExpense	(46,000,000)
Cash and Cash Equivalents, Period Increase (Decrease)	us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease	293,000,000
Net Cash Provided by (Used in) Investing Activities	us-gaap_NetCashProvidedByUsedInInvestingActivities	(343,000,000)
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan	us-gaap_ProceedsFromIssuanceOfCommonStockDividendReinvestmentPlan	2,000,000
Increase (Decrease) in Inventories	us-gaap_IncreaseDecreaseInInventories	4,000,000
Pepco Holdings LLC [Member] | Successor [Member]
Distribution to members	exc_DistributionToMembers	(174,000,000)
Payments for (Proceeds from) Other Investing Activities	us-gaap_PaymentsForProceedsFromOtherInvestingActivities	(13,000,000)
Unrealized Gain (Loss) on Derivatives	us-gaap_UnrealizedGainLossOnDerivatives	0
Change Receivables Payables From Affiliates	exc_ChangeReceivablesPayablesFromAffiliates	39,000,000
Increase (Decrease) in Receivables	us-gaap_IncreaseDecreaseInReceivables	94,000,000
Proceeds from Issuance of Preferred Stock and Preference Stock	us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock	0
Proceeds from (Payments for) Other Financing Activities	us-gaap_ProceedsFromPaymentsForOtherFinancingActivities	(3,000,000)
Payments to Acquire Marketable Securities	us-gaap_PaymentsToAcquireMarketableSecurities	0
Increase (Decrease) in Accounts Payable and Accrued Liabilities	us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	(23,000,000)
Proceeds from Issuance of Long-term Debt	us-gaap_ProceedsFromIssuanceOfLongTermDebt	2,000,000
Proceeds from (Repayments of) Short-term Debt, Maturing in Three Months or Less	us-gaap_ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	(520,000,000)
Pension and Other Postretirement Benefit Contributions	us-gaap_PensionAndOtherPostretirementBenefitContributions	13,000,000
Deferred Income Taxes and Tax Credits	us-gaap_DeferredIncomeTaxesAndTaxCredits	237,000,000
Payments of Ordinary Dividends, Common Stock	us-gaap_PaymentsOfDividendsCommonStock	0
Payments to Acquire Property, Plant, and Equipment	us-gaap_PaymentsToAcquirePropertyPlantAndEquipment	624,000,000
Increase (Decrease) Cash Collateral from Counterparties	us-gaap_IncreaseDecreaseCashCollateralFromCounterparties	0
Proceeds from Short-term Debt, Maturing in More than Three Months	us-gaap_ProceedsFromShortTermDebtMaturingInMoreThanThreeMonths	0
Increase (Decrease) in Income Taxes Payable	us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable	(57,000,000)
Change in Exelon intercompany money pool borrowings	exc_ChangeInExelonIntercompanyMoneyPoolBorrowings	1,000,000
Increase (Decrease) in Restricted Cash	us-gaap_IncreaseDecreaseInRestrictedCash	39,000,000
Repayments of Long-term Debt	us-gaap_RepaymentsOfLongTermDebt	29,000,000
Proceeds from Sale of Property Held-for-sale	us-gaap_ProceedsFromSaleOfPropertyHeldForSale	19,000,000
Other Noncash Income (Expense)	us-gaap_OtherNoncashIncomeExpense	(441,000,000)
Cash and Cash Equivalents, Period Increase (Decrease)	us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease	(20,000,000)
Net Cash Provided by (Used in) Investing Activities	us-gaap_NetCashProvidedByUsedInInvestingActivities	(631,000,000)
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan	us-gaap_ProceedsFromIssuanceOfCommonStockDividendReinvestmentPlan	0
Repayments of Debt, Maturing in More than Three Months	us-gaap_RepaymentsOfDebtMaturingInMoreThanThreeMonths	300,000,000
Increase (Decrease) in Inventories	us-gaap_IncreaseDecreaseInInventories	0
Pepco Holdings LLC [Member] | Commitments [Member] | Common Stock Including Additional Paid in Capital [Member] | Successor [Member]
Payments to Acquire Businesses, Gross	us-gaap_PaymentsToAcquireBusinessesGross	$ 33,000,000