Commonwealth Edison 10-Q 9 Aug 16 2016 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information	6 Months Ended
	Jun. 30, 2016shares
Entity Registrant Name	EXELON CORP
Entity Central Index Key	1,109,357
Document Type	10-Q
Document Period End Date	Jun. 30, 2016
Amendment Flag	false
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q2
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	922,872,373
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	127,017,042
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
		Jun. 30, 2016	Jun. 30, 2016	Mar. 23, 2016	Jun. 30, 2015	Jun. 30, 2016		Jun. 30, 2015
Gain (Loss) on Disposition of Assets	[1]							$ (26)
Operating revenues [Abstract]
Electrical Generation Revenue		$ 3,234			$ 4,080	$ 7,708		9,714
Gas Domestic Regulated Revenue		197			165	641		788
Operating revenues from affiliates		1			1
Regulated Operating Revenue		3,676			2,434	6,777		5,631
Electric Revenue		3,480			2,270	6,136		4,844
Revenues		6,910			6,514	14,485		15,345
Operating expenses
Purchased power		1,576			1,848	4,016		5,274
Cost of Purchased Power		878			601	1,692		1,645
Operating and maintenance		2,505			2,042	5,341		4,123
Depreciation and amortization		941			602	1,626		1,212
Taxes other than income		394			294	720		598
Total operating expenses		6,294			5,387	13,395		12,852
Gain (Loss) on Sale of Assets and Asset Impairment Charges		31			7	40		8
Operating income		647			1,134	1,130		2,501
Other income and (deductions)
Interest expense, net		(366)			(145)	(643)		(480)
Interest expense to affiliates		(10)			(10)	(20)		(21)
Other, net		144			(17)	258		64
Total other income and (deductions)		(232)			(172)	(405)		(437)
Income before income taxes		415			962	725		2,064
Income taxes		102			327	285		690
Income (Loss) from Equity Method Investments, Net of Dividends or Distributions		(7)			(2)	(10)		(2)
Net income		306			633	430		1,372
Net income (loss) attributable to noncontrolling interests and preference stock dividends		39			(5)	(10)		41
Net income attributable to common shareholders		267			638	440		1,331
Other comprehensive income (loss), net of income taxes
Prior service benefit reclassified to periodic benefit cost		(12)			(11)	(23)		(23)
Actuarial loss reclassified to periodic benefit cost		46			55	93		110
Pension and non-pension postretirement benefit plan valuation adjustment		(1)			0	(3)		(29)
Unrealized (loss) gain on cash flow hedges		0			3	(7)		9
Unrealized loss on equity investments		(4)			0	(7)		0
Unrealized gain on marketable securities		2			0	0		0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax		0			3	6		(9)
Other comprehensive income		31			50	59	[2]	58	[2]
Comprehensive income		337			683	489		1,430
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest		39			(5)	(10)		41
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest		$ 298			$ 688	$ 499		$ 1,389
Average shares of common stock outstanding:
Weighted average common shares outstanding — basic		924			863	923		862
Average common shares outstanding — diluted		926			866	926		866
Earnings per average common share:
Earnings per share - basic (in usd per share)		$ 0.29			$ 0.74	$ 0.48		$ 1.54
Earnings per average common share - diluted
Earnings per share - diluted (in usd per share)		0.29			0.74	0.48		1.54
Dividends per common share (in usd per share)		$ 0.318			$ 0.31	$ 0.628		$ 0.62
PECO Energy Co [Member]
Operating revenues [Abstract]
Gas Domestic Regulated Revenue		$ 77			$ 79	$ 273		$ 386
Operating revenues from affiliates		2			0	4		1
Electric Revenue		585			582	1,228		1,259
Revenues		664			661	1,505		1,646
Operating expenses
Utilities Operating Expense, Purchased Power		130			161	295		377
Purchased power and fuel from affiliates		64			48	142		110
Utilities Operating Expense, Fuel Used		23			28	100		188
Operating and maintenance		157			166	333		363
Operating and maintenance from affiliates		33			26	72		51
Depreciation and amortization		67			69	134		131
Taxes other than income		38			39	80		80
Total operating expenses		512			537	1,156		1,300
Gain (Loss) on Disposition of Other Assets						0		1
Operating income		152			124	349		347
Other income and (deductions)
Interest expense, net		(28)			(25)	(56)		(50)
Interest expense to affiliates		(3)			(3)	(6)		(6)
Other, net		2			1	4		3
Total other income and (deductions)		(29)			(27)	(58)		(53)
Income before income taxes		123			97	291		294
Income taxes		23			27	67		85
Net income		100			70	224		209
Other comprehensive income (loss), net of income taxes
Other comprehensive income	[2]							0
Comprehensive income		100			70	224		209
Exelon Generation Co L L C [Member]
Gain (Loss) on Disposition of Assets								0
Operating revenues [Abstract]
Electrical Generation Revenue		3,231			4,079	7,702		9,709
Operating revenues from affiliates		358			153	627		365
Revenues		3,589			4,232	8,329		10,074
Operating expenses
Cost of Purchased Power		1,575			1,848	4,015		5,274
Purchased power and fuel from affiliates		2			1	5		8
Operating and maintenance		1,369			1,149	2,665		2,311
Operating and maintenance from affiliates		161			159	332		308
Depreciation and amortization		408			255	697		509
Taxes other than income		118			124	244		246
Total operating expenses		3,633			3,536	7,958		8,656
Gain (Loss) on Sale of Assets and Asset Impairment Charges		31			7	31		6
Operating income		(13)			703	402		1,424
Other income and (deductions)
Interest expense, net		(89)			(90)	(176)		(180)
Interest expense to affiliates		(10)			(9)	(20)		(21)
Other, net		117			(31)	210		62
Total other income and (deductions)		18			(130)	14		(139)
Income before income taxes		5			573	416		1,285
Income taxes		(31)			181	120		407
Income (Loss) from Equity Method Investments, Net of Dividends or Distributions		(8)			(2)	(11)		(3)
Net income		28			390	285		875
Net income (loss) attributable to noncontrolling interests		36			(8)	(17)		34
Net (loss) income attributable to membership interest		(8)			398	302		841
Other comprehensive income (loss), net of income taxes
Unrealized (loss) gain on cash flow hedges		1			2	(4)		(3)
Unrealized loss on equity investments		(2)			0	(4)		0
Unrealized gain on marketable securities		1			1	0		1
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax		0			3	6		(9)
Other comprehensive income		0			6	(2)	[2]	(11)	[2]
Comprehensive income		28			396	283		864
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest		36			(8)	(17)		34
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest		(8)			404	300		830
Commonwealth Edison Co [Member]
Operating revenues [Abstract]
Operating revenues		1,283			1,147	2,527		2,331
Operating revenues from affiliates		3			1	8		2
Revenues		1,286			1,148	2,535		2,333
Operating expenses
Cost of Purchased Power		326			269	668		586
Purchased power and fuel from affiliates		13			6	18		15
Operating and maintenance		318			337	623		670
Operating and maintenance from affiliates		50			47	113		92
Depreciation and amortization		190			177	379		352
Taxes other than income		65			69	141		146
Total operating expenses		962			905	1,942		1,861
Gain (Loss) on Sale of Assets and Asset Impairment Charges		0			0	5		0
Operating income		324			243	598		472
Other income and (deductions)
Interest expense, net		(88)			(78)	(170)		(158)
Interest expense to affiliates		(3)			(3)	(7)		(7)
Other, net		3			5	7		9
Total other income and (deductions)		(88)			(76)	(170)		(156)
Income before income taxes		236			167	428		316
Income taxes		91			68	168		127
Net income		145			99	260		189
Other comprehensive income (loss), net of income taxes
Comprehensive income		145			99	260		189
Baltimore Gas and Electric Company [Member]
Operating revenues [Abstract]
Gas Domestic Regulated Revenue		94			86	340		402
Operating revenues from affiliates		4			1	9		8
Electric Revenue		582			541	1,260		1,254
Revenues		680			628	1,609		1,664
Operating expenses
Utilities Operating Expense, Purchased Power		108			130	235		338
Purchased power and fuel from affiliates		133			96	304		233
Utilities Operating Expense, Fuel Used		20			13	95		155
Operating and maintenance		177			120	345		276
Operating and maintenance from affiliates		31			29	65		55
Depreciation and amortization		97			87	206		192
Taxes other than income		55			54	114		111
Total operating expenses		621			529	1,364		1,360
Operating income		59			99	245		304
Other income and (deductions)
Interest expense, net		(20)			(20)	(40)		(42)
Interest expense to affiliates		(4)			(4)	(8)		(8)
Other, net		5			4	11		8
Total other income and (deductions)		(19)			(20)	(37)		(42)
Income before income taxes		40			79	208		262
Income taxes		6			32	73		105
Net income		34			47	135		157
Preferred security dividends and redemption		3			3	6		6
Net income attributable to common shareholders		31			44	129		151
Other comprehensive income (loss), net of income taxes
Comprehensive income		34			47	135		157
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest		3			3	6		6
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest		31			44	129		151
Pepco Holdings LLC [Member] | Predecessor [Member]
Operating revenues [Abstract]
Gas Domestic Regulated Revenue				$ 57	25			111
Operating revenues from affiliates				0	0			0
Electric Revenue				1,096	1,094			2,362
Revenues				1,153	1,119			2,473
Operating expenses
Cost of Purchased Power				471	417			1,005
Purchased power and fuel from affiliates				0	0			0
Utilities Operating Expense, Fuel Used				26	12			62
Operating and maintenance				294	288			589
Operating and maintenance from affiliates				0	0			0
Depreciation and amortization				152	152			307
Taxes other than income				105	111			229
Total operating expenses				1,048	980			2,192
Operating income				105	139			281
Other income and (deductions)
Interest expense, net				(65)	(71)			(140)
Other, net				(4)	12			21
Total other income and (deductions)				(69)	(59)			(119)
Income before income taxes				36	80			162
Income taxes				17	27			56
Net income				19	53			106
Other comprehensive income (loss), net of income taxes
Actuarial loss reclassified to periodic benefit cost				1	3			4
Other comprehensive income				1	3			4
Comprehensive income				$ 20	56			110
Pepco Holdings LLC [Member] | Successor [Member]
Operating revenues [Abstract]
Gas Domestic Regulated Revenue		26	$ 28
Operating revenues from affiliates		10	23
Electric Revenue		1,030	1,120
Revenues		1,066	1,171
Operating expenses
Cost of Purchased Power		263	288
Purchased power and fuel from affiliates		144	155
Utilities Operating Expense, Fuel Used		9	11
Operating and maintenance		223	670
Operating and maintenance from affiliates		23	25
Depreciation and amortization		160	174
Taxes other than income		108	123
Total operating expenses		930	1,446
Operating income		136	(275)
Other income and (deductions)
Interest expense, net		(66)	(71)
Other, net		11	12
Total other income and (deductions)		(55)	(59)
Income before income taxes		81	(334)
Income taxes		29	(77)
Net income		52	(257)
Other comprehensive income (loss), net of income taxes
Actuarial loss reclassified to periodic benefit cost		0	0
Other comprehensive income		0	0
Comprehensive income		52	$ (257)
Potomac Electric Power Company [Member]
Gain (Loss) on Disposition of Assets		8				8
Operating revenues [Abstract]
Operating revenues from affiliates		1			1	3		2
Electric Revenue		508			503	1,058		1,047
Revenues		509			504	1,061		1,049
Operating expenses
Cost of Purchased Power		64			162	256		373
Purchased power and fuel from affiliates		88			0	95		0
Operating and maintenance		100			102	389		213
Operating and maintenance from affiliates		9			1	10		2
Depreciation and amortization		70			63	144		125
Taxes other than income		89			93	182		190
Total operating expenses		420			421	1,076		903
Operating income		97			83	(7)		146
Other income and (deductions)
Interest expense, net		(31)			(31)	(68)		(61)
Other, net		6			8	14		13
Total other income and (deductions)		(25)			(23)	(54)		(48)
Income before income taxes		72			60	(61)		98
Income taxes		23			18	(1)		30
Net income		49			42	(60)		68
Other comprehensive income (loss), net of income taxes
Comprehensive income		49			42	(60)		68
Delmarva Power and Light Company [Member]
Operating revenues [Abstract]
Gas Domestic Regulated Revenue		26			25	85		111
Operating revenues from affiliates		2			2	4		3
Electric Revenue		253			244	554		577
Revenues		281			271	643		691
Operating expenses
Utilities Operating Expense, Purchased Power		70			114	216		292
Purchased power and fuel from affiliates		43			0	47		0
Utilities Operating Expense, Fuel Used		9			11	35		58
Operating and maintenance		73			74	277		156
Operating and maintenance from affiliates		5			1	6		1
Depreciation and amortization		38			35	76		74
Taxes other than income		13			12	28		24
Total operating expenses		251			247	685		605
Operating income		30			24	(42)		86
Other income and (deductions)
Interest expense, net		(13)			(13)	(25)		(25)
Other, net		3			2	6		5
Total other income and (deductions)		(10)			(11)	(19)		(20)
Income before income taxes		20			13	(61)		66
Income taxes		8			5	(1)		26
Net income		12			8	(60)		40
Other comprehensive income (loss), net of income taxes
Comprehensive income		12			8	(60)		40
Atlantic City Electric Company [Member]
Gain (Loss) on Disposition of Assets		1				1
Operating revenues [Abstract]
Operating revenues from affiliates		1			1	2		2
Electric Revenue		269			284	559		616
Revenues		270			285	561		618
Operating expenses
Cost of Purchased Power		129			147	285		338
Purchased power and fuel from affiliates		12			0	13		0
Operating and maintenance		63			68	275		136
Operating and maintenance from affiliates		5			1	5		2
Depreciation and amortization		41			43	81		86
Taxes other than income		2			1	4		3
Total operating expenses		252			260	663		565
Operating income		19			25	(101)		53
Other income and (deductions)
Interest expense, net		(16)			(16)	(32)		(32)
Other, net		2			1	5		3
Total other income and (deductions)		(14)			(15)	(27)		(29)
Income before income taxes		5			10	(128)		24
Income taxes		2			4	(31)		9
Net income		3			6	(97)		15
Other comprehensive income (loss), net of income taxes
Comprehensive income		$ 3			$ 6	$ (97)		$ 15
[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. Amounts in parenthesis represent a decrease in AOCI.

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities
Net income	$ 430	$ 1,372
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	2,396	1,957
Impairment of long-lived assets and losses on regulatory assets	239	24
Gain on sales of assets	(40)	(8)
Deferred income taxes and amortization of investment tax credits	(261)	(211)
Net fair value changes related to derivatives	194	(507)
Gain (Loss) on Investments	114	2
Other non-cash operating activities	1,056	579
Changes in assets and liabilities:
Inventories	89	159
Accounts receivable	86	253
Accounts payable and accrued expenses	(363)	(540)
Option premiums received, net	(10)	22
Collateral received, net	710	659
Income taxes	470	247
Pension and non-pension postretirement benefit contributions	(258)	(301)
Other assets and liabilities	(593)	(156)
Net cash flows provided by operating activities	4,553	3,969
Cash flows from investing activities
Capital expenditures	(4,489)	(3,460)
Proceeds from nuclear decommissioning trust fund sales	4,977	3,314
Investment in nuclear decommissioning trust funds	(5,094)	(3,437)
Acquisition of businesses, net of cash acquired	(6,642)	(28)
Proceeds from Sale of Property Held-for-sale	45	145
Proceeds from termination of direct financing lease investment	360	0
Change in restricted cash	15	(3)
Other investing activities	(49)	(77)
Net cash flows used in investing activities	(10,877)	(3,546)
Cash flows from financing activities
Changes in short-term borrowings	798	(94)
Proceeds from short-term borrowings with maturities greater than 90 days	(194)	0
Issuance of long-term debt	3,174	5,907
Retirement of long-term debt	(217)	(1,708)
Dividends paid on common stock	(582)	(537)
Proceeds from employee stock plans	17	16
Other financing activities	4	59
Net cash flows provided by financing activities	1,469	3,713
Repayments of Short-term Debt, Maturing in More than Three Months	(315)	0
(Decrease) Increase in cash and cash equivalents	(4,855)	4,136
Cash and cash equivalents at beginning of period	6,502	1,878
Cash and cash equivalents at end of period	1,647	6,014
Exelon Generation Co L L C [Member]
Cash flows from operating activities
Net income	285	875
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	1,467	1,255
Impairment of long-lived assets and losses on regulatory assets	179	(1)
Gain on sales of assets	(31)	(6)
Deferred income taxes and amortization of investment tax credits	59	(65)
Net fair value changes related to derivatives	199	(396)
Gain (Loss) on Investments	114	2
Other non-cash operating activities	169	134
Changes in assets and liabilities:
Inventories	57	134
Accounts receivable	123	291
Change Receivables Payables From Affiliates	(77)	(11)
Accounts payable and accrued expenses	(228)	(369)
Option premiums received, net	(10)	22
Collateral received, net	720	682
Income taxes	41	27
Pension and non-pension postretirement benefit contributions	(117)	(122)
Other assets and liabilities	(217)	(155)
Net cash flows provided by operating activities	2,387	2,423
Cash flows from investing activities
Capital expenditures	(2,051)	(1,764)
Proceeds from nuclear decommissioning trust fund sales	4,977	3,314
Investment in nuclear decommissioning trust funds	(5,094)	(3,437)
Acquisition of businesses, net of cash acquired	(1)	(28)
Proceeds from Sale of Property Held-for-sale	30	144
Change in restricted cash	25	(16)
Other investing activities	(96)	(63)
Net cash flows used in investing activities	(2,210)	(1,850)
Cash flows from financing activities
Changes in short-term borrowings	0	(15)
Repayments of Debt, Maturing in More than Three Months	(15)	0
Issuance of long-term debt	173	1,307
Proceeds from Debt, Maturing in More than Three Months	194	0
Retirement of long-term debt	(131)	(39)
Repayments of Related Party Debt	0	(550)
Other financing activities	(39)	6
Distribution to member	(111)	(2,262)
Proceeds from Contributions from Affiliates	45	0
Change in Exelon intercompany money pool borrowings	(429)	638
Net cash flows provided by financing activities	(235)	(897)
(Decrease) Increase in cash and cash equivalents	(58)	(324)
Cash and cash equivalents at beginning of period	431	780
Cash and cash equivalents at end of period	373	456
Commonwealth Edison Co [Member]
Cash flows from operating activities
Net income	260	189
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	379	352
Gain on sales of assets	(5)	0
Deferred income taxes and amortization of investment tax credits	(222)	(36)
Other non-cash operating activities	83	222
Changes in assets and liabilities:
Inventories	7	(19)
Accounts receivable	(36)	(57)
Change Receivables Payables From Affiliates	1	(10)
Accounts payable and accrued expenses	(42)	(53)
Collateral received, net	(10)	0
Income taxes	261	239
Pension and non-pension postretirement benefit contributions	(35)	(125)
Other assets and liabilities	38	26
Net cash flows provided by operating activities	1,128	800
Cash flows from investing activities
Capital expenditures	(1,334)	(1,061)
Other investing activities	21	17
Net cash flows used in investing activities	(1,313)	(1,044)
Cash flows from financing activities
Changes in short-term borrowings	259	(199)
Issuance of long-term debt	1,200	400
Retirement of long-term debt	0	(260)
Dividends paid on common stock	(183)	(150)
Other financing activities	17	5
Contributions from parent	(113)	(45)
Net cash flows provided by financing activities	854	229
(Decrease) Increase in cash and cash equivalents	669	(15)
Cash and cash equivalents at beginning of period	67	66
Cash and cash equivalents at end of period	736	51
PECO Energy Co [Member]
Cash flows from operating activities
Net income	224	209
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	134	131
Deferred income taxes and amortization of investment tax credits	(51)	(4)
Other non-cash operating activities	27	45
Changes in assets and liabilities:
Inventories	19	21
Accounts receivable	(1)	(18)
Change Receivables Payables From Affiliates	(2)	(2)
Accounts payable and accrued expenses	(19)	3
Income taxes	31	57
Pension and non-pension postretirement benefit contributions	(29)	(15)
Other assets and liabilities	(96)	(60)
Net cash flows provided by operating activities	339	375
Cash flows from investing activities
Capital expenditures	(299)	(289)
Change in restricted cash	0	(1)
Other investing activities	8	9
Net cash flows used in investing activities	(291)	(281)
Cash flows from financing activities
Dividends paid on common stock	(139)	(139)
Other financing activities	1	0
Change in Exelon intercompany money pool borrowings		41
Net cash flows provided by financing activities	(140)	(98)
(Decrease) Increase in cash and cash equivalents	(92)	(4)
Cash and cash equivalents at beginning of period	295	30
Cash and cash equivalents at end of period	203	26
Baltimore Gas and Electric Company [Member]
Cash flows from operating activities
Net income	135	157
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	206	192
Impairment of long-lived assets and losses on regulatory assets	52
Deferred income taxes and amortization of investment tax credits	(17)	(54)
Other non-cash operating activities	60	76
Changes in assets and liabilities:
Inventories	6	23
Accounts receivable	11	25
Change Receivables Payables From Affiliates	6	(2)
Accounts payable and accrued expenses	(5)	(59)
Collateral received, net	0	(23)
Income taxes	46	(6)
Pension and non-pension postretirement benefit contributions	(42)	(9)
Other assets and liabilities	(3)	61
Net cash flows provided by operating activities	489	489
Cash flows from investing activities
Capital expenditures	(392)	(304)
Change in restricted cash	5	21
Other investing activities	12	8
Net cash flows used in investing activities	(375)	(275)
Cash flows from financing activities
Changes in short-term borrowings	2	120
Retirement of long-term debt	(39)	(37)
Dividends paid on common stock	(90)	(77)
Other financing activities	2	14
Contributions from parent	(21)	0
Dividends paid on preference stock	(6)	(6)
Net cash flows provided by financing activities	(118)	(254)
(Decrease) Increase in cash and cash equivalents	(4)	(40)
Cash and cash equivalents at beginning of period	9	64
Cash and cash equivalents at end of period	5	24
Pepco Holdings LLC [Member] | Successor [Member]
Cash flows from financing activities
Cash and cash equivalents at end of period	294
Pepco Holdings LLC [Member] | Predecessor [Member]
Cash flows from operating activities
Net income		106
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
Deferred income taxes and amortization of investment tax credits		(73)
Net fair value changes related to derivatives		0
Other non-cash operating activities		101
Changes in assets and liabilities:
Inventories		0
Accounts receivable		(196)
Change Receivables Payables From Affiliates		0
Accounts payable and accrued expenses		19
Collateral received, net		0
Income taxes		0
Pension and non-pension postretirement benefit contributions		(8)
Other assets and liabilities		(63)
Net cash flows provided by operating activities		339
Cash flows from investing activities
Capital expenditures		(562)
Purchases of investments		0
Change in restricted cash		11
Other investing activities		(2)
Net cash flows used in investing activities		(553)
Cash flows from financing activities
Changes in short-term borrowings		(69)
Proceeds from short-term borrowings with maturities greater than 90 days		0
Issuance of long-term debt		408
Retirement of long-term debt		(138)
Dividends paid on common stock		(137)
Common stock issued for the Direct Stock Purchase and Dividend Reinvestment Plan and employee-related compensation		19
Distribution to member		0
Other financing activities		24
Contributions from parent		0
Change in Exelon intercompany money pool borrowings		0
Issuance of preferred stock		36
Net cash flows provided by financing activities		233
(Decrease) Increase in cash and cash equivalents		19
Cash and cash equivalents at beginning of period	26	15
Cash and cash equivalents at end of period		34
Potomac Electric Power Company [Member]
Cash flows from operating activities
Net income	(60)	68
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	144	125
Deferred income taxes and amortization of investment tax credits	(20)	(31)
Other non-cash operating activities	158	33
Changes in assets and liabilities:
Inventories	1	(4)
Accounts receivable	(41)	(99)
Change Receivables Payables From Affiliates	47	2
Accounts payable and accrued expenses	(19)	(9)
Income taxes	165	0
Pension and non-pension postretirement benefit contributions	(3)	(6)
Other assets and liabilities	(47)	(36)
Net cash flows provided by operating activities	365	105
Cash flows from investing activities
Capital expenditures	(256)	(254)
Proceeds from Sale of Property Held-for-sale	12
Purchases of investments	(31)	0
Change in restricted cash	(31)	3
Other investing activities	(1)	3
Net cash flows used in investing activities	(307)	(248)
Cash flows from financing activities
Changes in short-term borrowings	64	104
Issuance of long-term debt	1	208
Retirement of long-term debt	(5)	(17)
Dividends paid on common stock	(55)	(31)
Other financing activities	0	9
Contributions from parent	(187)	(112)
Net cash flows provided by financing activities	64	159
(Decrease) Increase in cash and cash equivalents	122	16
Cash and cash equivalents at beginning of period	5	6
Cash and cash equivalents at end of period	127	22
Delmarva Power and Light Company [Member]
Cash flows from operating activities
Net income	(60)	40
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	76	74
Deferred income taxes and amortization of investment tax credits	(23)	(26)
Other non-cash operating activities	121	22
Changes in assets and liabilities:
Inventories	1	6
Accounts receivable	30	(43)
Change Receivables Payables From Affiliates	15	3
Accounts payable and accrued expenses	(2)	(9)
Collateral received, net	1	0
Income taxes	66	0
Other assets and liabilities	(51)	(4)
Net cash flows provided by operating activities	220	115
Cash flows from investing activities
Capital expenditures	(182)	(154)
Change in restricted cash	(1)	5
Other investing activities	3	1
Net cash flows used in investing activities	(180)	(148)
Cash flows from financing activities
Changes in short-term borrowings	105	76
Issuance of long-term debt	0	200
Retirement of long-term debt	0	(100)
Dividends paid on common stock	(38)	(62)
Other financing activities	0	2
Contributions from parent	(113)	(75)
Net cash flows provided by financing activities	(30)	35
(Decrease) Increase in cash and cash equivalents	10	2
Cash and cash equivalents at beginning of period	5	4
Cash and cash equivalents at end of period	15	6
Atlantic City Electric Company [Member]
Cash flows from operating activities
Net income	(97)	15
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	81	86
Deferred income taxes and amortization of investment tax credits	28	(9)
Other non-cash operating activities	138	17
Changes in assets and liabilities:
Inventories	(2)	(1)
Accounts receivable	31	(55)
Change Receivables Payables From Affiliates	8	0
Accounts payable and accrued expenses	6	37
Income taxes	181	(1)
Other assets and liabilities	(110)	(24)
Net cash flows provided by operating activities	208	83
Cash flows from investing activities
Capital expenditures	(164)	(138)
Proceeds from Sale of Property Held-for-sale	2	0
Change in restricted cash	1	0
Other investing activities	1	(2)
Net cash flows used in investing activities	(160)	(140)
Cash flows from financing activities
Changes in short-term borrowings	5	(91)
Retirement of long-term debt	(22)	(21)
Dividends paid on common stock	(11)	(12)
Other financing activities	1	0
Contributions from parent	(139)	0
Net cash flows provided by financing activities	100	58
(Decrease) Increase in cash and cash equivalents	148	1
Cash and cash equivalents at beginning of period	3	2
Cash and cash equivalents at end of period	$ 151	$ 3

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions		Jun. 30, 2016	Dec. 31, 2015
Assets, Current [Abstract]
Cash and cash equivalents		$ 1,647	$ 6,502
Restricted cash and cash equivalents		201	205
Accounts receivable, net
Customer		3,671	3,187
Other		988	912
Mark-to-market derivative assets		759	1,365
Unamortized energy contract assets		69	86
Inventories, net
Fossil fuel and emission allowances		317	462
Materials and supplies		1,183	1,104
Regulatory assets		1,559	759
Other		1,101	752
Total current assets		11,495	15,334
Property, plant and equipment, net		70,693	57,439
Deferred debits and other assets
Regulatory assets		10,121	6,065
Nuclear decommissioning trust funds		10,737	10,342
Investments		502	639
Goodwill		6,696	2,672
Mark-to-market derivative assets		546	758
Unamortized energy contract assets		461	484
Pledged assets for Zion Station decommissioning		161	206
Other		1,366	1,445
Total deferred debits and other assets		30,590	22,611
Total assets		112,778	95,384
Liabilities, Current [Abstract]
Short-term borrowings		951	533
Long-term debt due within one year		2,693	1,500
Accounts payable		2,826	2,883
Accrued expenses		2,757	2,376
Payables to affiliates		8	8
Regulatory liabilities		503	369
Mark-to-market derivative liabilities (current liabilities)		152	205
Unamortized energy contract liabilities		508	100
Other		1,025	842
Energy Marketing Accounts Payable		316	302
Accounts Payable and Accrued Liabilities, Current		155
Total current liabilities		11,894	9,118
Long-term debt		31,541	23,645
Long-term debt to financing trusts		641	641
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net		17,662	13,776
Asset Retirement Obligations, Noncurrent		9,256	8,585
Pension obligations		3,767	3,385
Non-pension postretirement benefit obligations		1,900	1,618
Spent nuclear fuel obligation		1,023	1,021
Regulatory liabilities		4,389	4,201
Mark-to-market derivative liabilities (noncurrent liabilities)		442	374
Unamortized energy contract liabilities		1,011	117
Payable for Zion Station decommissioning		54	90
Other		1,876	1,491
Total deferred credits and other liabilities		41,380	34,658
Total liabilities	[1]	85,456	68,062
Redeemable Noncontrolling Interest, Equity, Common, Carrying Amount		24	28
Commitments and contingencies
Preferred Stock, Value, Issued		193	193
Stockholders' Equity Attributable to Parent [Abstract]
Common stock		18,722	18,676
Treasury stock, at cost (35 shares at June 30, 2016 and December 31, 2015, respectively)		(2,327)	(2,327)
Retained earnings		11,926	12,068
Accumulated other comprehensive loss, net	[2]	(2,565)	(2,624)
Total shareholders’ equity		25,756	25,793
Preferred Stock, Value, Issued		193	193
Noncontrolling interests		1,349	1,308
Total equity		27,298	27,294
Total liabilities and shareholders’ equity		112,778	95,384
Member’s equity
Retained Earnings (Accumulated Deficit)		11,926	12,068
Accumulated other comprehensive loss, net	[2]	(2,565)	(2,624)
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	[3]	387	147
Variable Interest Entity, Primary Beneficiary [Member]
Assets, Current [Abstract]
Cash and cash equivalents		138	164
Restricted cash and cash equivalents		53	100
Accounts receivable, net
Customer		253	219
Other		44	43
Mark-to-market derivative assets		41	140
Inventories, net
Materials and supplies		189	181
Other		37	35
Total current assets		755	882
Property, plant and equipment, net		5,147	5,160
Deferred debits and other assets
Nuclear decommissioning trust funds		2,100	2,036
Goodwill		47	47
Mark-to-market derivative assets		24	53
Other		167	90
Total assets		8,240	8,268
Liabilities, Current [Abstract]
Long-term debt due within one year		312	111
Accounts payable		146	216
Accrued expenses		79	115
Mark-to-market derivative liabilities (current liabilities)		21	5
Unamortized energy contract liabilities		13	12
Other		23	13
Total current liabilities		594	472
Long-term debt		675	666
Deferred credits and other liabilities
Asset Retirement Obligations, Noncurrent	[4]	2,053	1,999
Pension obligations		9	9
Unamortized energy contract liabilities		31	39
Other		99	79
Total liabilities		3,461	3,264
Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Deferred debits and other assets
Total assets		8,240	8,268
Deferred credits and other liabilities
Total liabilities		3,461	3,264
Exelon Generation Co L L C [Member]
Assets, Current [Abstract]
Cash and cash equivalents		373	431
Restricted cash and cash equivalents		98	123
Accounts receivable, net
Customer		2,076	2,095
Other		325	360
Mark-to-market derivative assets		759	1,365
Unamortized energy contract assets		69	86
Receivables from affiliates		184	83
Inventories, net
Fossil fuel and emission allowances		266	384
Materials and supplies		840	880
Other		735	535
Total current assets		5,725	6,342
Property, plant and equipment, net		26,656	25,843
Deferred debits and other assets
Nuclear decommissioning trust funds		10,737	10,342
Investments		294	210
Goodwill		47	47
Mark-to-market derivative assets		499	733
Unamortized energy contract assets		460	484
Deferred Tax Assets, Net, Noncurrent		13	6
Pledged assets for Zion Station decommissioning		161	206
Other		632	627
Prepaid pension asset		1,673	1,689
Total deferred debits and other assets		14,516	14,344
Total assets		46,897	46,529
Liabilities, Current [Abstract]
Short-term borrowings		208	29
Long-term debt due within one year		174	90
Accounts payable		1,271	1,583
Accrued expenses		743	935
Payables to affiliates		110	104
Other Short-term Borrowings		817	1,252
Mark-to-market derivative liabilities (current liabilities)		134	182
Unamortized energy contract liabilities		75	100
Other		339	356
Energy Marketing Accounts Payable		316	302
Total current liabilities		4,187	4,933
Long-term debt		7,965	7,936
Long-term debt to affiliate		927	933
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net		5,750	5,845
Asset Retirement Obligations, Noncurrent		9,081	8,431
Non-pension postretirement benefit obligations		935	924
Spent nuclear fuel obligation		1,023	1,021
Due to Affiliate, Noncurrent		2,643	2,577
Mark-to-market derivative liabilities (noncurrent liabilities)		237	150
Unamortized energy contract liabilities		94	117
Payable for Zion Station decommissioning		54	90
Other		634	602
Total deferred credits and other liabilities		20,451	19,757
Total liabilities	[5]	33,530	33,559
Redeemable Noncontrolling Interest, Equity, Common, Carrying Amount		24	28
Commitments and contingencies
Stockholders' Equity Attributable to Parent [Abstract]
Retained earnings		2,892	2,701
Accumulated other comprehensive loss, net	[2]	(65)	(63)
Noncontrolling interests		1,348	1,307
Total liabilities and shareholders’ equity		46,897	46,529
Member’s equity
Members' Capital		9,168	8,997
Retained Earnings (Accumulated Deficit)		2,892	2,701
Accumulated other comprehensive loss, net	[2]	(65)	(63)
Total member's equity		11,995	11,635
Limited Liability Company (LLC) Members' Equity, Including Portion Attributable to Noncontrolling Interest		13,343	12,942
Exelon Generation Co L L C [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Assets, Current [Abstract]
Cash and cash equivalents		138	164
Restricted cash and cash equivalents		26	77
Accounts receivable, net
Customer		253	219
Other		44	43
Mark-to-market derivative assets		41	140
Inventories, net
Materials and supplies		189	181
Other		30	30
Total current assets		721	854
Property, plant and equipment, net		5,147	5,160
Deferred debits and other assets
Nuclear decommissioning trust funds		2,100	2,036
Goodwill		47	47
Mark-to-market derivative assets		24	53
Other		133	85
Total assets		8,172	8,235
Liabilities, Current [Abstract]
Long-term debt due within one year		183	27
Accounts payable		146	216
Accrued expenses		76	113
Mark-to-market derivative liabilities (current liabilities)		21	5
Unamortized energy contract liabilities		13	12
Other		23	13
Total current liabilities		462	386
Long-term debt		557	623
Deferred credits and other liabilities
Asset Retirement Obligations, Noncurrent		2,053	1,999	[4]
Pension obligations		9	9
Unamortized energy contract liabilities		31	39
Other		99	79
Total liabilities		3,211	3,135
Exelon Generation Co L L C [Member] | Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Deferred debits and other assets
Total assets		8,172	8,235
Deferred credits and other liabilities
Total liabilities		3,211	3,135
Commonwealth Edison Co [Member]
Assets, Current [Abstract]
Cash and cash equivalents		736	67
Restricted cash and cash equivalents		2	2
Accounts receivable, net
Customer		557	533
Other		237	272
Receivables from affiliates		206	199
Inventories, net
Regulatory assets		213	218
Other		68	63
Inventories, net		155	164
Total current assets		2,174	1,518
Property, plant and equipment, net		18,416	17,502
Deferred debits and other assets
Regulatory assets		923	895
Investments		6	6
Goodwill		2,625	2,625
Other		324	324
Receivable from affiliate		2,205	2,172
Prepaid pension asset		1,432	1,490
Total deferred debits and other assets		7,515	7,512
Total assets		28,105	26,532
Liabilities, Current [Abstract]
Short-term borrowings		35	294
Long-term debt due within one year		665	665
Accounts payable		609	660
Accrued expenses		929	706
Payables to affiliates		65	62
Regulatory liabilities		153	155
Mark-to-market derivative liabilities (current liabilities)		18	23
Other		77	70
Customer deposits		128	131
Total current liabilities		2,679	2,766
Long-term debt		7,030	5,844
Long-term debt to financing trusts		205	205
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net		5,142	4,914
Asset Retirement Obligations, Noncurrent		114	111
Non-pension postretirement benefit obligations		249	259
Regulatory liabilities		3,524	3,459
Mark-to-market derivative liabilities (noncurrent liabilities)		203	224
Other		521	507
Total deferred credits and other liabilities		9,753	9,474
Total liabilities		19,667	18,289
Commitments and contingencies
Stockholders' Equity Attributable to Parent [Abstract]
Common stock		1,588	1,588
Retained earnings		1,055	978
Other paid-in capital		5,795	5,677
Total shareholders’ equity		8,438	8,243
Total liabilities and shareholders’ equity		28,105	26,532
Member’s equity
Retained Earnings (Accumulated Deficit)		1,055	978
PECO Energy Co [Member]
Assets, Current [Abstract]
Cash and cash equivalents		203	295
Restricted cash and cash equivalents		3	3
Accounts receivable, net
Customer		248	258
Other		126	146
Receivables from affiliates		5	2
Inventories, net
Fossil fuel and emission allowances		24	43
Materials and supplies		26	26
Regulatory assets		48	34
Other		34	24
Prepaid utility taxes		84	11
Total current assets		801	842
Property, plant and equipment, net		7,303	7,141
Deferred debits and other assets
Regulatory assets		1,636	1,583
Investments		26	28
Other		21	21
Receivable from affiliate		438	405
Prepaid pension asset		361	347
Total deferred debits and other assets		2,482	2,384
Total assets		10,586	10,367
Liabilities, Current [Abstract]
Long-term debt due within one year		300	300
Accounts payable		269	281
Accrued expenses		100	109
Payables to affiliates		56	55
Regulatory liabilities		128	112
Other		39	29
Customer deposits		60	58
Total current liabilities		952	944
Long-term debt		2,281	2,280
Long-term debt to financing trusts		184	184
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net		2,920	2,792
Asset Retirement Obligations, Noncurrent		27	27
Non-pension postretirement benefit obligations		288	287
Regulatory liabilities		529	527
Other		84	90
Total deferred credits and other liabilities		3,848	3,723
Total liabilities		7,265	7,131
Commitments and contingencies
Stockholders' Equity Attributable to Parent [Abstract]
Common stock		2,455	2,455
Retained earnings		865	780
Accumulated other comprehensive loss, net	[2]	1	1
Total shareholders’ equity		3,321	3,236
Total liabilities and shareholders’ equity		10,586	10,367
Member’s equity
Retained Earnings (Accumulated Deficit)		865	780
Accumulated other comprehensive loss, net	[2]	1	1
Baltimore Gas and Electric Company [Member]
Assets, Current [Abstract]
Cash and cash equivalents		5	9
Restricted cash and cash equivalents		19	24
Accounts receivable, net
Customer		289	300
Other		70	112
Inventories, net
Fossil fuel and emission allowances		22	36
Materials and supplies		41	33
Regulatory assets		261	267
Other		7	3
Prepaid utility taxes		0	61
Total current assets		714	845
Property, plant and equipment, net		6,747	6,597
Deferred debits and other assets
Regulatory assets		520	514
Investments		12	12
Other		9	8
Prepaid pension asset		323	319
Total deferred debits and other assets		864	853
Total assets		8,325	8,295
Liabilities, Current [Abstract]
Short-term borrowings		208	210
Long-term debt due within one year		380	378
Accounts payable		222	209
Accrued expenses		101	110
Payables to affiliates		58	52
Regulatory liabilities		60	38
Other		30	35
Customer deposits		106	102
Total current liabilities		1,165	1,134
Long-term debt		1,440	1,480
Long-term debt to financing trusts		252	252
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net		2,111	2,081
Asset Retirement Obligations, Noncurrent		15	17
Non-pension postretirement benefit obligations		204	209
Regulatory liabilities		137	184
Other		71	61
Total deferred credits and other liabilities		2,538	2,552
Total liabilities	[6]	5,395	5,418
Preferred Stock, Value, Issued		190	190
Stockholders' Equity Attributable to Parent [Abstract]
Common stock		1,381	1,367
Retained earnings		1,359	1,320
Total shareholders’ equity		2,740	2,687
Preferred Stock, Value, Issued		190	190
Total equity		2,930	2,877
Total liabilities and shareholders’ equity		8,325	8,295
Member’s equity
Retained Earnings (Accumulated Deficit)		1,359	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		17	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		17	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		20	26
Liabilities, Current [Abstract]
Long-term debt due within one year		81	79
Accounts payable		0	0
Accrued expenses		1	2
Mark-to-market derivative liabilities (current liabilities)		0	0
Unamortized energy contract liabilities		0	0
Other		0	0
Total current liabilities		82	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		82	122
Baltimore Gas and Electric Company [Member] | Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Deferred debits and other assets
Total assets		20	26
Deferred credits and other liabilities
Total liabilities		82	122
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
Notes and Loans, Noncurrent			4
Goodwill			1,406
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
Preferred Stock, Shares Outstanding			18,000
Preferred Stock, Value, Issued			$ 183
Stockholders' Equity Attributable to Parent [Abstract]
Retained earnings			617
Accumulated other comprehensive loss, net			(36)
Preferred Stock, Value, Issued			183
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		294
Restricted cash and cash equivalents		44
Accounts receivable, net
Customer		501
Other		237
Mark-to-market derivative assets		0
Inventories, net
Fossil fuel and emission allowances		5
Materials and supplies		121
Regulatory assets		730
Other		87
Total current assets		2,019
Property, plant and equipment, net		11,148
Deferred debits and other assets
Regulatory assets		3,044
Investments		131
Notes and Loans, Noncurrent		4
Goodwill		4,024
Mark-to-market derivative assets		0
Deferred Tax Assets, Net, Noncurrent		5
Other		57
Prepaid pension asset		489
Total deferred debits and other assets		7,754
Total assets		20,921
Liabilities, Current [Abstract]
Short-term borrowings		500
Long-term debt due within one year		551
Accounts payable		344
Accrued expenses		306
Payables to affiliates		90
Exelon Money Pool Borrowing Current		34
Regulatory liabilities		101
Mark-to-market derivative liabilities (current liabilities)		0
Unamortized energy contract liabilities		433
Other		31
Customer deposits		128
Payables to Customers		118
Total current liabilities		2,636
Long-term debt		5,522
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net		3,470
Asset Retirement Obligations, Noncurrent		12
Pension obligations		0
Non-pension postretirement benefit obligations		141
Regulatory liabilities		171
Mark-to-market derivative liabilities (noncurrent liabilities)		0
Unamortized energy contract liabilities		918
Other		280
Total deferred credits and other liabilities		4,992
Total liabilities		13,150
Preferred Stock, Value, Issued		0
Stockholders' Equity Attributable to Parent [Abstract]
Retained earnings		(257)
Accumulated other comprehensive loss, net		0
Preferred Stock, Value, Issued		0
Total liabilities and shareholders’ equity		20,921
Member’s equity
Members' Capital		8,028
Retained Earnings (Accumulated Deficit)		(257)
Accumulated other comprehensive loss, net		0
Total member's equity		7,771
Limited Liability Company (LLC) Members' Equity, Including Portion Attributable to Noncontrolling Interest		7,771
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		10
Accounts receivable, net
Customer		0
Other		0
Mark-to-market derivative assets		0
Inventories, net
Materials and supplies		0
Other		4
Total current assets		14
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		45
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		118
Deferred credits and other liabilities
Asset Retirement Obligations, Noncurrent		0
Pension obligations	[4]	0
Unamortized energy contract liabilities		0
Other		0
Total liabilities		166
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		45
Deferred credits and other liabilities
Total liabilities		166
Potomac Electric Power Company [Member]
Assets, Current [Abstract]
Cash and cash equivalents		127	5
Restricted cash and cash equivalents		33	2
Accounts receivable, net
Customer		255	230
Other		116	261
Inventories, net
Materials and supplies		65	67
Regulatory assets		129	140
Other		9	21
Total current assets		734	726
Property, plant and equipment, net		5,321	5,162
Deferred debits and other assets
Regulatory assets		669	661
Investments		99	68
Other		4	4
Prepaid pension asset		272	287
Total deferred debits and other assets		1,044	1,020
Total assets		7,099	6,908
Liabilities, Current [Abstract]
Short-term borrowings		0	64
Long-term debt due within one year		12	11
Accounts payable		127	145
Accrued expenses		141	119
Payables to affiliates		77	30
Regulatory liabilities		27	15
Other		13	25
Customer deposits		54	46
Payables to Customers		42	0
Total current liabilities		493	455
Long-term debt		2,337	2,340
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net		1,755	1,723
Non-pension postretirement benefit obligations		48	49
Regulatory liabilities		24	29
Other		163	72
Total deferred credits and other liabilities		1,990	1,873
Total liabilities		4,820	4,668
Stockholders' Equity Attributable to Parent [Abstract]
Common stock		1,309	1,122
Other paid-in capital		970	1,118
Total shareholders’ equity		2,279	2,240
Total equity		2,279	2,240
Total liabilities and shareholders’ equity		7,099	6,908
Delmarva Power and Light Company [Member]
Assets, Current [Abstract]
Cash and cash equivalents		15	5
Restricted cash and cash equivalents		1	0
Accounts receivable, net
Customer		124	154
Other		32	96
Unamortized energy contract assets		16	9
Inventories, net
Fossil fuel and emission allowances		5	8
Materials and supplies		33	32
Regulatory assets		63	72
Other		1	12
Total current assets		290	388
Property, plant and equipment, net		3,177	3,070
Deferred debits and other assets
Regulatory assets		295	299
Goodwill		8	8
Other		8	2
Prepaid pension asset		193	202
Total deferred debits and other assets		504	511
Total assets		3,971	3,969
Liabilities, Current [Abstract]
Short-term borrowings		0	105
Long-term debt due within one year		218	204
Accounts payable		93	109
Accrued expenses		45	31
Payables to affiliates		37	20
Regulatory liabilities		53	49
Other		7	15
Customer deposits		38	31
Payables to Customers		27	0
Total current liabilities		518	564
Long-term debt		1,047	1,061
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net		968	945
Non-pension postretirement benefit obligations		20	19
Regulatory liabilities		102	111
Other		64	32
Total deferred credits and other liabilities		1,154	1,107
Total liabilities		2,719	2,732
Stockholders' Equity Attributable to Parent [Abstract]
Common stock		725	612
Retained earnings		527	625
Total shareholders’ equity		1,252	1,237
Total liabilities and shareholders’ equity		3,971	3,969
Member’s equity
Retained Earnings (Accumulated Deficit)		527	625
Atlantic City Electric Company [Member]
Assets, Current [Abstract]
Cash and cash equivalents		151	3
Restricted cash and cash equivalents		10	12
Accounts receivable, net
Customer		122	156
Other		69	242
Due from Affiliates		1	0
Inventories, net
Materials and supplies		23	23
Regulatory assets		97	98
Other		4	12
Prepaid utility taxes		36	0
Total current assets		513	546
Property, plant and equipment, net		2,427	2,322
Deferred debits and other assets
Regulatory assets		418	414
Notes and Loans, Noncurrent		4	4
Other		23	19
Prepaid pension asset		76	82
Total deferred debits and other assets		521	519
Total assets		3,461	3,387
Liabilities, Current [Abstract]
Short-term borrowings		0	5
Long-term debt due within one year		44	48
Accounts payable		107	96
Accrued expenses		86	70
Payables to affiliates		25	16
Regulatory liabilities		21	18
Other		7	14
Customer deposits		37	30
Payables to Customers		48	0
Total current liabilities		375	297
Long-term debt		1,136	1,153
Deferred credits and other liabilities
Deferred Income Tax Liabilities, Net		859	885
Non-pension postretirement benefit obligations		35	33
Regulatory liabilities		2	7
Other		23	12
Total deferred credits and other liabilities		919	937
Total liabilities		2,430	2,387
Stockholders' Equity Attributable to Parent [Abstract]
Common stock		912	773
Retained earnings		119	227
Total shareholders’ equity		1,031	1,000
Total liabilities and shareholders’ equity		3,461	3,387
Member’s equity
Retained Earnings (Accumulated Deficit)		119	227
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities		150	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		10	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		10	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		29	30
Liabilities, Current [Abstract]
Long-term debt due within one year		42	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		44	48
Long-term debt		106	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		$ 150	$ 172
[1]	Exelon’s consolidated assets include $8,240 million and $8,268 million at June 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 $3,461 million and $3,264 million at June 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. 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 $8,172 million and $8,235 million at June 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 $3,211 million and $3,135 million at June 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 $20 million and $26 million at June 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 $82 million and $122 million at June 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	Jun. 30, 2016	Dec. 31, 2015
Common Stock, Shares Authorized	2,000,000,000	2,000,000,000
Stockholders' Equity Attributable to Parent [Abstract]
Assets	$ 112,778	$ 95,384
Treasury Stock, Shares held	35,000,000
Exelon Generation Co L L C [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets	$ 46,897	46,529
Commonwealth Edison Co [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets	28,105	26,532
PECO Energy Co [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets	10,586	10,367
Baltimore Gas and Electric Company [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets	8,325	8,295
Potomac Electric Power Company [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets	7,099	6,908
Delmarva Power and Light Company [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets	3,971	3,969
Atlantic City Electric Company [Member]
Noncontrolling Interest in Variable Interest Entity	29	30
Stockholders' Equity Attributable to Parent [Abstract]
Assets	3,461	$ 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	$ 20,921

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]Other Additional Capital [Member]	Commonwealth Edison Co [Member]Retained Earnings, Unappropriated [Member]	Commonwealth Edison Co [Member]Retained Earnings, Appropriated [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]Nonredeemable Preferred Stock [Member]	Baltimore Gas and Electric Company [Member]Retained Earnings [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]	Deferred Compensation, Share-based Payments [Member]Pepco Holdings LLC [Member]	Commitments [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]																														$ 4
Other Comprehensive Income (Loss), Net of Tax	[1]	58								(11)											0
Net income | Predecessor [Member]																														106
Net income		1,372								875						$ 189					209					$ 157											$ 68			$ 40			$ 15
Proceeds from Contributions from Parent | Predecessor [Member]																														0
Proceeds from Contributions from Parent																45										0											112			75			0
Payments to Acquire Businesses, Gross		(28)								(28)
Other Comprehensive Income (Loss), Net of Tax | Predecessor [Member]																														3
Other Comprehensive Income (Loss), Net of Tax		50								6
Net income | Predecessor [Member]																														53
Net income		633								390						99					70					47											42			8			6
Accumulated other comprehensive loss, net	[1]	(2,626)								(47)											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
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	$ 5,677	$ (1,639)	$ 2,617	3,236		$ 2,455	$ 780	$ 1	2,687	$ 1,367	$ 190	$ 1,320								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				1
Stock Issued During Period, Value, Employee Stock Purchase Plan | Predecessor [Member]																														3
Net income | Predecessor [Member]																														19			19
Employee stock purchase plan issuances | Predecessor [Member]																														3
Other comprehensive loss, net of income taxes of $53 | Predecessor [Member]																														1
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	5,677	(1,639)	2,617	3,236		2,455	780	1	2,687	1,367	190	1,320								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		59	[1]							(2)	[1]	0	(2)	0
Stock Issued During Period, Value, Employee Stock Purchase Plan		$ 17		17
Stock Issued During Period, Shares, Employee Stock Purchase Plans		599
Net income		$ 430				440		(17)	7	285		302	0	(17)		260			260		224			224		135		0	135								(60)		(60)	(60)		(60)	(97)		(97)	$ (262)
Distribution Made to Limited Liability Company (LLC) Member, Cash Distributions Declared | Successor [Member]																														(16)
Distribution Made to Limited Liability Company (LLC) Member, Cash Distributions Declared										111		111														(7)	(7)		0
Noncontrolling Interest, Increase from Sale of Parent Equity Interest										52
Long-term incentive plan activity (in shares)		2,349
Long-term incentive plan activity		$ 47		47
Employee stock purchase plan issuances (in shares)		599
Employee stock purchase plan issuances		$ 17		17
Appropriation of retained earnings for future dividends																0			(260)	260
Tax benefit on stock compensation		(18)		(18)
Common stock dividends		(582)				(582)			(7)							(183)				(183)	(139)			(139)		(90)		0	90											38		38	(11)		(11)
Contribution from parent										171					171	113		113								21	21		0								187	187		113	113		139	139
Dividends																																					(88)		(88)
Allocation of tax benefit from parent																5		5
Minority Interest Increase From Acquisition		2						2		2				2
Preferred security dividends		(7)																								(6)		0	(6)
Temporary Equity, Other Changes		(56)						(56)		56				(56)
Other comprehensive loss, net of income taxes of $53		59					59
Ending Balance at Jun. 30, 2016		$ 27,298		18,722	(2,327)	11,926	(2,565)	1,349	193																	2,930											2,279
Ending Balance (in shares) at Jun. 30, 2016		957,616
Ending Balance at Jun. 30, 2016		$ 25,756														8,438	1,588	5,795	(1,639)	2,694	3,321		2,455	865	1	2,740	1,381	190	1,359								2,279	1,309	970	1,252	725	527	1,031	912	119
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from Contributions from Parent																113										21											187			113			139
Payments to Acquire Businesses, Gross		(6,642)								(1)
Common Stock, Value, Issued | Predecessor [Member]																														3		$ 3
Additional Paid in Capital | Predecessor [Member]																															$ 3,835
Payments to Acquire Businesses, Gross | Successor [Member]																																															$ (29)	$ (33)
Beginning Balance (Predecessor [Member]) at Mar. 23, 2016																														4,439			636	(35)	3,838
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax | Successor [Member]																														0
Net income | Successor [Member]																														(257)			(257)
Contribution from parent | Successor [Member]																														1,088
Ending Balance at Jun. 30, 2016		$ 27,298		18,722	(2,327)	11,926	(2,565)	1,349	193																	2,930											2,279
Ending Balance (in shares) at Jun. 30, 2016		957,616
Ending Balance at Jun. 30, 2016		$ 25,756														8,438	1,588	5,795	(1,639)	2,694	3,321		2,455	865	1	2,740	1,381	190	1,359								2,279	1,309	970	1,252	725	527	1,031	912	119
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from Contributions from Parent | Successor [Member]																														1,088
Payments to Acquire Businesses, Gross | Successor [Member]																																														(62)	$ (29)
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]																														235
Business Combination, Separately Recognized Transactions, Assets Recognized | Successor [Member]																														53
Fresh-Start Adjustment, Increase (Decrease), Deferred Income Tax Liabilities, Noncurrent | Successor [Member]																																				$ 59
Net income | Successor [Member]																																				$ 0
Ending Balance at Jun. 30, 2016		$ 27,298		18,722	(2,327)	11,926	(2,565)	1,349	193																	2,930											2,279
Ending Balance (in shares) at Jun. 30, 2016		957,616
Ending Balance at Jun. 30, 2016		$ 25,756														8,438	1,588	5,795	(1,639)	2,694	3,321		2,455	865	1	2,740	1,381	190	1,359								2,279	1,309	970	1,252	725	527	1,031	912	119
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax | Successor [Member]																														0
Other Comprehensive Income (Loss), Net of Tax		31								0
Net income | Successor [Member]																														52
Net income		306								28						145					100					34											49			12			3			$ 52
Ending Balance at Jun. 30, 2016		$ 27,298		$ 18,722	$ (2,327)	$ 11,926	$ (2,565)	$ 1,349	$ 193																	2,930											2,279
Ending Balance (in shares) at Jun. 30, 2016		957,616
Ending Balance at Jun. 30, 2016		$ 25,756														8,438	$ 1,588	$ 5,795	$ (1,639)	$ 2,694	3,321		$ 2,455	$ 865	$ 1	2,740	$ 1,381	$ 190	$ 1,359								2,279	$ 1,309	$ 970	1,252	$ 725	$ 527	1,031	$ 912	$ 119
Common Stock, Value, Issued		18,722														1,588					2,455					1,381											1,309			725			912
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance | Successor [Member]																														8,028					$ 8,028
Beginning Balance										9,168					$ 9,168
Retained Earnings (Accumulated Deficit) | Successor [Member]																														(257)			$ (257)
Retained Earnings (Accumulated Deficit)		11,926								2,892		$ 2,892				1,055					865					$ 1,359														$ 527			$ 119
Accumulated other comprehensive loss, net | Successor [Member]																														0				$ 0
Accumulated other comprehensive loss, net		(2,565)	[1]							(65)	[1]		$ (65)	$ 1,348							$ 1	[1]
Limited Liability Company (LLC) Members' Equity, Including Portion Attributable to Noncontrolling Interest | Successor [Member]																														7,771
Limited Liability Company (LLC) Members' Equity, Including Portion Attributable to Noncontrolling Interest										13,343
Business Combination, Contingent Consideration, Asset | Successor [Member]																														(251)
Business Combination, Contingent Consideration, Asset		(235)								(163)
Additional Paid in Capital																$ 5,795																					$ 970
Derivative Asset, Noncurrent | Successor [Member]																														$ 0
Derivative Asset, Noncurrent		$ 546								$ 499
[1]	All amounts are net of tax. 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		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income taxes	$ 102	$ 327	$ 285	$ 690
Exelon Generation Co L L C [Member]
Income taxes	(31)	181	120	407
Atlantic City Electric Company [Member]
Income taxes	2	4	(31)	9
PECO Energy Co [Member]
Income taxes	23	27	67	85
Commonwealth Edison Co [Member]
Income taxes	91	68	168	127
Baltimore Gas and Electric Company [Member]
Income taxes	6	32	73	105
Potomac Electric Power Company [Member]
Income taxes	$ 23	$ 18	$ (1)	$ 30

Significant Accounting Policies

Significant Accounting Policies	6 Months Ended
	Jun. 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. During preparation of the June 30, 2016 financial statements, an error was identified related to the PHI successor period Consolidated Statement of Cash Flows for the period March 24, 2016 to March 31, 2016. The $46 million classification error related to the presentation of changes in Receivables from and payables to affiliates, net within Cash flows from operating activities and Change in Exelon intercompany money pool within Cash flows from financing activities. This was corrected for the period of March 24, 2016 to June 30, 2016 and will be revised within the first quarter 2017 Form 10-Q when the March 24 to March 31, 2016 successor period will next be disclosed. As revised, the successor period statement of cash flows for the period March 24, 2016 to March 31, 2016 will present Cash flows used in operating activities of $3 million , a decrease of $46 million from the originally reported amount, and Cash flows used in financing activities of $135 million , a decrease of $46 million from the originally reported amount. Management has concluded that the error is not material to the previously issued financial statements. 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 is a decrease of $4 million for the three months ended June 30, 2015 and an increase of $1 million for the six months ended June 30, 2015 . 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 three and six months ended June 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 June 30, 2016 and 2015 and for the three and six 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)	6 Months Ended
	Jun. 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 June 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 June 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 a total of $250 million of equity incrementally from inception through December 2016 in proportion to their ownership interests, which equates to approximately $172 million for the tax equity investor and $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 June 30, 2016 and December 31, 2015 , ComEd, PECO, Pepco and DPL did not have any material consolidated VIEs. As of June 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 June 30, 2016 , the remaining obligation is $308 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 June 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 $13 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 six months ended June 30, 2016 , BGE remitted $21 million and $42 million to BondCo, respectively. During the three and six months ended June 30, 2015 , BGE remitted $21 million and $42 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 six months ended June 30, 2016 , ACE transferred $12 million and $26 million to ATF, respectively. During the three and six months ended June 30, 2015 , ACE transferred $14 million and $27 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 June 30, 2016 and December 31, 2015 are as follows: June 30, 2016 December 31, 2015 Successor Predecessor Exelon (a)(b) Generation BGE PHI (b) ACE Exelon (a) Generation BGE PHI ACE Current assets $ 818 $ 784 $ 17 $ 14 $ 10 $ 909 $ 881 $ 23 $ 12 $ 12 Noncurrent assets 8,083 8,048 3 31 19 8,009 8,004 3 18 18 Total assets $ 8,901 $ 8,832 $ 20 $ 45 $ 29 $ 8,918 $ 8,885 $ 26 $ 30 $ 30 Current liabilities $ 597 $ 464 $ 82 48 $ 44 $ 473 $ 387 $ 81 $ 48 $ 48 Noncurrent liabilities 3,070 2,951 — 118 106 2,927 2,884 41 124 124 Total liabilities $ 3,667 $ 3,415 $ 82 $ 166 $ 150 $ 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 June 30, 2016 and December 31, 2015 , these assets and liabilities primarily consisted of the following: June 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 $ 138 $ 138 $ — $ — $ — $ 164 $ 164 $ — $ — $ — Restricted cash 53 26 17 10 10 100 77 23 12 12 Accounts receivable, net Customer 253 253 — — — 219 219 — — — Other 44 44 — — — 43 43 — — — Mark-to-market derivatives assets 41 41 — — — 140 140 — — — Inventory Materials and supplies 189 189 — — — 181 181 — — — Other current assets 37 30 — 4 — 35 30 — — — Total current assets 755 721 17 14 10 882 854 23 12 12 Property, plant and equipment, net 5,147 5,147 — — — 5,160 5,160 — — — Nuclear decommissioning trust funds 2,100 2,100 — — — 2,036 2,036 — — — Goodwill 47 47 — — — 47 47 — — — Mark-to-market derivatives assets 24 24 — — — 53 53 — — — Other noncurrent assets 167 133 3 31 19 90 85 3 18 18 Total noncurrent assets 7,485 7,451 3 31 19 7,386 7,381 3 18 18 Total assets $ 8,240 $ 8,172 $ 20 $ 45 $ 29 $ 8,268 $ 8,235 $ 26 $ 30 $ 30 Long-term debt due within one year $ 312 $ 183 $ 81 $ 46 $ 42 $ 111 $ 27 $ 79 $ 46 $ 46 Accounts payable 146 146 — — — 216 216 — — — Accrued expenses 79 76 1 2 2 115 113 2 2 2 Mark-to-market derivative liabilities 21 21 — — — 5 5 — — — Unamortized energy contract liabilities 13 13 — — — 12 12 — — — Other current liabilities 23 23 — — — 13 13 — — — Total current liabilities 594 462 82 48 44 472 386 81 48 48 Long-term debt 675 557 — 118 106 666 623 41 124 124 Asset retirement obligations 2,053 2,053 — — — 1,999 1,999 — — — Pension obligation (c) 9 9 — — — 9 9 — — — Unamortized energy contract liabilities 31 31 — — — 39 39 — — — Other noncurrent liabilities 99 99 — — — 79 79 — — — Total noncurrent liabilities 2,867 2,749 — 118 106 2,792 2,749 41 124 124 Total liabilities $ 3,461 $ 3,211 $ 82 $ 166 $ 150 $ 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 June 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 $18 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 $18 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 a total of $250 million of equity incrementally from inception through December 2016 in proportion of their ownership interests, which equates to approximately $172 million for the tax equity investor and $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: June 30, 2016 Commercial Agreement VIEs Equity Investment VIEs Total Total assets (a) $ 503 $ 395 $ 898 Total liabilities (a) 106 281 387 Exelon's ownership interest in VIE (a) — 80 80 Other ownership interests in VIE (a) 397 34 431 Registrants’ maximum exposure to loss: Carrying amount of equity method investments — 137 137 Contract intangible asset 9 — 9 Debt and payment guarantees — 3 3 Net assets pledged for Zion Station decommissioning (b) 13 — 13 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 $161 million and $206 million as of June 30, 2016 and December 31, 2015 , respectively; offset by payables to ZionSolutions LLC of $148 million and $189 million as of June 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	6 Months Ended
	Jun. 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. Exelon estimates total commitments of approximately $444 million on a net present value basis (excluding charitable contributions and renewable generation commitments) will be provided. The actual cost of commitments may differ by a material amount depending on the result of final negotiations and application of the most favored nation provision. The following pre-tax costs were recognized, including the estimated impacts of applying the most favored nation provision, after the closing of the merger and are included 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 six months ended June 30, 2016 and PHI's successor Consolidated Statements of Operations and Comprehensive Income: Expected Payment Period Successor Description Pepco DPL ACE PHI Exelon Customer bill credit 2016 - 2017 $ 65 $ 58 $ 62 $ 185 $ 185 Energy efficiency 2016 - 2021 — — — — 64 Charitable contributions 2016 - 2026 28 12 10 50 50 Customer base rate credit 2016 - 2019 26 — — 26 26 Delivery system modernization Q2 2016 — — — — 22 Green sustainability fund Q2 2016 — — — — 14 Workforce development 2016 - 2020 — — — — 11 Most favored nation 19 32 48 99 129 Other 1 2 — 3 7 Total $ 139 $ 104 $ 120 $ 363 $ 508 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 and the District of Columbia, 27 MWs of which are expected to be completed by 2018. These investments are expected to total approximately $130 million , are expected to be primarily capital in nature, and will generate future earnings at Exelon and Generation. The actual cost of new generation may differ by a material amount 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 has been 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 Exelon aided and abetted the individual directors’ breaches. The suits seek rescission of the merger. In addition, they also seek unspecified damages and costs. Exelon was also named in a federal court suit making similar claims. On June 1, 2016, the parties executed a settlement to resolve all claims, subject to the approval of the Delaware Court. Exelon does not believe resolution of these suits will have a material impact on Exelon’s results of operations or cash flows. On July 21, 2015, the OPC filed a motion to stay the MDPSC order approving the merger and to set a schedule for discovery and presentation of new evidence. On July 29, 2015, Public Citizen, Inc. filed a response supporting OPC’s motion to stay, and on July 31, 2015 the Sierra Club and the Chesapeake Climate Action Network (CCAN) filed a joint motion to stay. 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. On March 25, 2016, Grid 2.0 filed an application for reconsideration of the DCPSC’s March 23, 2016 order approving the merger. On March 30, 2016, Exelon filed a reply to that application. On April 20, 2016, DC Public Power filed a motion to reconsider the DCPSC's March 23, 2016 order, motion to intervene and motion to consider alternative settlement provisions (namely, that the DCPSC consider requiring the post-merger divestiture of Pepco’s DC-based assets to a not-for-profit independent grid operator). On April 27, 2016, Exelon filed a reply to these motions. On April 22, 2016, (1) the District of Columbia Office of People’s Counsel, (2) the District of Columbia Government, and (3) DC Sun and Public Citizen each filed separate applications for reconsideration of the DCPSC’s March 23, 2016 order. On April 29, 2016, Exelon filed a reply to these applications. These applications for reconsideration generally argue that the DCPSC violated its regulations, utilized improper processes, abused its discretion, acted arbitrarily and capriciously, committed legal error and denied due process in approving the merger under terms that revised the Settlement Agreement offered by the companies and various parties. On June 17, 2016, the DCPSC denied all motions. The parties have until August 16, 2016 to appeal the DCPSC decision. 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, if not sooner. During the second quarter, certain modifications were made to preliminary valuation amounts for acquired unamortized energy contracts, long-term debt and pension and OPEB liability resulting in an $8 million net increase 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 11,076 Regulatory assets 5,015 Other assets 248 Goodwill 4,024 Total assets $ 21,804 Current liabilities $ 2,763 Unamortized energy contracts 1,515 Regulatory liabilities 297 Long-term debt, including current maturities 5,636 Deferred income taxes 3,443 Pension and OPEB liability 821 Other liabilities 187 Total liabilities $ 14,662 Total purchase price $ 7,142 During preparation of the June 30, 2016 financial statements, an error was identified related to the preliminary purchase price allocation table above as originally reported in the first quarter 2016 Form 10-Q. The error resulted in a gross up of certain assets and liabilities related to legacy PHI intercompany and income tax receivable and payable balances that were not properly reflected in the first quarter 2016 Form 10-Q disclosure, with no impact on reported net assets acquired or goodwill. The correction of the disclosure error has been reflected in the table presented above. As revised, the Current assets, Other assets, Current liabilities, Long-term debt, including current maturities, Deferred income taxes, and Other liabilities would have been disclosed as $1,441 million , $249 million , $2,764 million , $5,661 million , $3,448 million and $187 million , respectively, within the first quarter 2016 Form 10-Q. Management has concluded that the disclosure error is not material to the previously issued financial statements. 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 , $1.2 billion and $1.1 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 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 six months ended June 30, 2016 was as follows: PHI Exelon (a) Beginning balance $ — $ 2,672 Goodwill from business combination 4,016 4,016 Measurement period adjustment 8 8 Ending balance $ 4,024 $ 6,696 _____________ (a) As of June 30, 2016 , there were no changes to the carrying amount of goodwill for ComEd and Generation, 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 June 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 $1,112 million and Net income of $52 million during the three months ended June 30, 2016 , and Operating revenues of $1,219 million and Net loss of $(262) million during the six months ended June 30, 2016 For the three and six months ended June 30, 2016 and 2015 , the Registrants have recognized costs to achieve the PHI acquisition as follows: Three Months Ended June 30, Six Months Ended June 30, Acquisition, Integration and Financing Costs (a) 2016 2015 2016 2015 Exelon (b) $ 1 $ (87 ) $ 103 $ 21 Generation 4 7 20 15 ComEd (c) 1 3 (7 ) 6 PECO 1 1 2 2 BGE (d) (5 ) 1 (4 ) 3 Pepco (d) (4 ) 1 23 2 DPL (d) — 1 16 1 ACE 2 1 15 1 Successor Predecessor Successor Predecessor Acquisition, Integration and Financing Costs (a) Three Months Ended Three Months Ended March 24, 2016 to June 30, 2016 January 1, 2016 to March 23, 2016 Six Months Ended June 30, 2015 PHI (d) $ (1 ) $ 5 $ 55 $ 29 $ 14 ______________ (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 six months ended June 30, 2016 , includes the reversal of previously incurred acquisition, integration and financing costs of $8 million incurred at ComEd that has been deferred and recorded as a regulatory asset for anticipated recovery. See Note 5 — Regulatory Matters for more information. (d) For the three and six months ended June 30, 2016 , includes the reversal of previously incurred acquisition, integration and financing costs of $6 million , $9 million , $3 million and $12 million incurred at 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 Six Months Ended Year Ended December 31, 2016 (a) 2015 (b) 2016 (a) 2015 (b) 2015 (c) Total operating revenues $ 6,910 $ 7,522 $ 15,466 $ 17,584 $ 33,823 Net income attributable to common shareholders 268 623 845 1,423 2,618 Basic earnings per share $ 0.29 $ 0.68 $ 0.92 $ 1.55 $ 2.85 Diluted earnings per share 0.29 0.67 0.91 1.54 2.84 ______________ (a) The amounts above include adjustments for non-recurring costs directly related to the merger of $1 million and $641 million for the three and six months ended June 30, 2016 , respectively, and intercompany revenue of $170 million for the six months ended June 30, 2016 . (b) The amounts above include adjustments for non-recurring costs directly related to the merger of $(82) million and $35 million and intercompany revenue of $111 million and $233 million for the three and six months ended June 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. Proposed Acquisition of ConEdison Solutions (Exelon and Generation) On July 27, 2016, Generation entered into an Asset Purchase Agreement (the Purchase Agreement) with ConEdison Solutions, a subsidiary of Consolidated Edison, Inc. (collectively ConEdison). Pursuant to the Purchase Agreement, ConEdison Solutions agreed to sell its competitive retail electric and natural gas business to Generation for an all cash purchase price of $53 million plus estimated purchase price adjustments, including net working capital, of $130 million . Pursuant to the Purchase Agreement, Generation has agreed to use its commercially reasonable efforts to replace the guarantees and other credit support currently being provided by ConEdison in support of the ongoing competitive retail electric and natural gas business and to reimburse ConEdison for any payments arising pursuant to such arrangements continuing for any post-closing period. The renewable energy, sustainable services and energy efficiency businesses of ConEdison are excluded from the transaction. The transaction is expected to close in the third or fourth quarter of 2016. The closing of the transaction is subject to certain conditions, including, obtaining the termination or expiration of any applicable waiting period required under the HSR Act for the consummation of the transaction. Either party may terminate the Purchase Agreement if the transaction has not been consummated within six months after the date of the Purchase Agreement. The Purchase Agreement also includes various representations, warranties, covenants, indemnifications and other provisions customary for a transaction of this nature. The total costs directly related to the closing of the transaction are not expected to have a material impact on the financial results of Exelon and Generation. The transaction is expected to be accounted for as a business combination. Therefore, 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. 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 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 refuel the plant and 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, a portion of which for financial reporting purposes will be evaluated as part of the purchase price consideration. 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. The transaction is expected to be accounted for as a business combination. Therefore, 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. 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 a result, $61 million of Property, plant and equipment and $5 million of Asset retirement obligation were reclassified as held for sale within Other current assets and Other current liabilities on Exelon’s and Generation’s Consolidated Balance Sheets.

Regulatory Matters (All Registr

Regulatory Matters (All Registrants)	6 Months Ended
	Jun. 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 numerous easements across the project route through voluntary transactions. ComEd is seeking to acquire the remaining rights either through settlement or condemnation proceedings that are currently pending in the relevant circuit courts. 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 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 is procuring 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. As of June 30, 2016 , PECO entered into contracts with PAPUC-approved bidders, including Generation, resulting from the first three 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. The program has a 24-month term from June 1, 2017 through May 31, 2019, and complies with electric generation procurement guidelines set forth in Act 129. A PAPUC ruling is expected in late 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 annual service revenues for electric delivery, 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. Any adjustments to rates approved by the MDPSC are expected to take effect in November 2016. Pepco cannot predict how much of the requested increase the MDPSC will approve. In addition to the proposed $127 million 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 whether 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, 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. 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 $66 million 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; and 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. BGE is evaluating its options as to the outstanding issues in its petition for rehearing. 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 June 30, 2016 and December 31, 2015 , BGE recorded a regulatory asset of $240 million and $196 million , respectively, representing incremental program costs, including a debt return thereon, and at June 30, 2016, $56 million of unamortized costs of the non-AMI meters replaced under the program. The balance as of June 30, 2016, reflects the impact of the cost disallowances and adjustments discussed below. This regulatory asset is being recovered through rates and amortized to expense over 10 years. As part of rate base, the regulatory asset is earning a return except for the $56 million portion reflecting the unamortized cost of the retired non-AMI meters and a $32 million portion related to post-test year incremental program 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 the benefits exceed the costs on a present value basis by a ratio of more than 2.0 to 1.0. 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. BGE is evaluating its options as to the outstanding issues in its petition for rehearing. 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 $56 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 June 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 June 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. 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 allows DPL to put into effect $2.5 million of the rate increase two months after filing the application and 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. 2013 Electric Distribution Base Rates (Exelon, PHI and DPL). In March 2013, and as amended on September 20, 2013, DPL filed for an electric distribution base rate increase with the DPSC, ultimately requesting an annual increase of $42 million . In August 2014, the DPSC issued a final order in DPL's 2013 electric distribution rate case for an annual increase of $15 million and an ROE of 9.70% . Rates became effective on May 1, 2014. In September 2014, DPL filed an appeal with the Delaware Superior Court of the DPSC’s August 2014 order in this proceeding, seeking the court’s review of the DPSC’s decision relating to the recovery of costs associated with one component of employee compensation, certain retirement benefits and credit facility expenses. The Division of the Public Advocate filed a cross-appeal in September 2014, pertaining to the treatment of a prepaid pension expense and other postretirement benefit obligations in base rates. Under the Settlement Agreement related to the Merger, the parties agreed to suspend the appeal and, upon consummation of the Merger, to the withdrawal of the appeal and the cross-appeal with prejudice. In accordance with the settlement, on April 13, 2016, the parties filed a Stipulation of Dismissal with the court to dismiss the appeal and the cross-appeal, and the case is now closed. 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 , based on a requested ROE of 10.6% . Pepco has requested that the DCPSC issue a final decision by May 29, 2017. Any adjustments to its rates approved by the DCPSC are expected to take effect in June 2017. Pepco cannot predict how much of the requested increase the DCPSC will approve. 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. This $1 billion initiative seeks to selectively place underground some of the District of Columbia’s most outage-prone power lines, which lines and surrounding conduit would be owned and maintained by Pepco. 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 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 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 and recovery of Pepco’s investment through a volumetric surcharge (the Triennial Plan), all in accordance with the Improvement Financing Act. In August 2014, Pepco filed an application for the issuance of a financing order to provide for the issuance of the District's bonds and a volumetric surcharge for the District to recover the costs associated with the bond issuance (the DDOT surcharge). In March 2015, a party to the DCPSC proceedings filed with the District of Columbia Court of Appeals a petition for review of the order approving the Triennial Plan and the issuance of the financing order. On January 14, 2016, the District of Columbia Court of Appeals affirmed the orders of the DCPSC. On January 27, 2016, the original petitioning party sought rehearing of the District of Columbia Court of Appeals decision. On March 17, 2016, the District of Columbia Court of Appeals denied the original petitioning party’s motion for rehearing. Separately, 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 March 22, 2016, as supplemented and updated on May 10, 2016, ACE filed an application with the NJBPU requesting an increase of $85 million (including New Jersey sales and use tax) to its annual service revenues for electric delivery, based on a requested ROE of 10.6% . In addition to the request for base rate relief, ACE has also included a request that the NJBPU approve ACE’s five-year grid resiliency initiative known as “PowerAhead.” As proposed, PowerAhead includes $176 million of 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. A decision is expected in the first half of 2017. ACE cannot predict how much of the requested increase the NJBPU will approve or if it will approve ACE's 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. Standard Offer Capacity Agreements (Exelon, PHI and ACE). On April 28, 2011, ACE entered into three SOCAs by order of the NJBPU, each with a different generation company. ACE and the other New Jersey EDCs entered into the SOCAs under protest, arguing that the EDCs were denied due process and that the SOCAs violated certain of the requirements of the New Jersey law under which the SOCAs were established (the NJ SOCA Law). On October 22, 2013, in light of the decision of the U.S. District Court for the District of New Jersey described below, the state appeals of the NJBPU implementation orders filed by the EDCs and generators were dismissed without prejudice, subject to the parties exercising their appellate rights in the Federal courts. In February 2011, ACE joined other plaintiffs in an action filed in the U.S. District Court for the District of New Jersey challenging the NJ SOCA Law on the grounds that it violates the Commerce Clause and the Supremacy Clause of the U.S. Constitution. In October 2013, the Federal district court issued a ruling that the NJ SOCA Law is preempted by the Federal Power Act (FPA) and violates the Supremacy Clause, and is therefore null and void. On October 11, 2013, the Federal district court issued an order ruling that the SOCAs are void, invalid and unenforceable, which order was affirmed by the U.S. Court of Appeals for the Third Circuit on September 11, 2014. On November 26, 2014 and December 10, 2014, respectively, one of the generation companies and the NJBPU petitioned the U.S. Supreme Court to consider hearing an appeal of the Third Circuit decision. On April 19, 2016, the U.S. Supreme Court unanimously affirmed the Fourth Circuit decision, discussed above under “MDPSC New Generation Contract Requirement,” holding that the MDPSC’s required contracts are illegal and unenforceable. On April 25, 2016, the U.S. Supreme Court ruled not to review the Third Circuit decision. This denial leaves the Third Circuit decision in place, with the same outcome as the Fourth Circuit decision. ACE terminated one of the three SOCAs effective July 1, 2013 due to the occurrence of an event of default on the part of the generation company counterparty. ACE terminated the remaining two SOCAs effective November 19, 2013, in response to the October 2013 Federal district court decision. New York Regulatory Matters Ginna Nuclear Power Plant Reliability Support Services Agreement (Exelon and Generation). In November 2014, in response to a petition filed by Ginna Nuclear Power Plant (Ginna) regarding the possible retirement of Ginna, the New York Public Service Commission (NYPSC) directed Gi

Impairment of Long-lived Assets

Impairment of Long-lived Assets (Exelon and Generation)	6 Months Ended
	Jun. 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 were classified as held for sale on Exelon's and Generation's Consolidated Balance Sheets at June 30, 2016 . See Note 4 — Mergers, Acquisitions and Dispositions for additional information. 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. The fair value analysis was primarily based on the income approach using significant unobservable inputs (Level 3) including commodity prices and production volumes, projected capital and maintenance expenditures and discount rates. 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 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)	6 Months Ended
	Jun. 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 the second quarter of 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 $141 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. Exelon's and Generation's second quarter 2016 results include an incremental $110 million of pre-tax expense for these items. 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. 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 2018, 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, the New York Public Service Commission (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 New York State Energy Research & Development Agency (NYSERDA), as required under the CES, and subject to any potential 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, Ginna is required to file a notice to that effect with the NYPSC no later than September 30, 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 June 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 $ 38 $ 30 $ 69 Nuclear fuel inventory, net 104 47 235 Completed plant, net 968 125 1,137 Construction work in progress 35 12 70 Liability Balances Asset retirement obligation (485 ) (659 ) (770 ) NRC License Renewal Term 2034 2029 2029 (unit 1) 2046 (unit 2) 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)	6 Months Ended
	Jun. 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 June 30, 2016 and December 31, 2015 : Exelon June 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 954 $ 3 $ 951 $ — $ 954 Long-term debt (including amounts due within one year) (a) 34,234 1,135 33,863 2,176 37,174 Long-term debt to financing trusts (b) 641 — — 689 689 SNF obligation 1,023 — 835 — 835 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 June 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 208 $ — $ 208 $ — $ 208 Long-term debt (including amounts due within one year) (a) 9,066 — 7,953 1,577 9,530 SNF obligation 1,023 — 835 — 835 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 June 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 35 $ — $ 35 $ — $ 35 Long-term debt (including amounts due within one year) (a) 7,695 — 8,832 — 8,832 Long-term debt to financing trusts (b) 205 — — 209 209 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 June 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 2,581 $ — $ 3,002 $ — $ 3,002 Long-term debt to financing trusts 184 — — 205 205 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 June 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 211 $ 3 $ 208 $ — $ 211 Long-term debt (including amounts due within one year) (a) 1,820 — 2,136 — 2,136 Long-term debt to financing trusts (b) 252 — — 275 275 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 June 30, 2016 Carrying Amount Fair Value Successor Level 1 Level 2 Level 3 Total Short-term liabilities $ 500 $ — $ 500 $ — $ 500 Long-term debt (including amounts due within one year) 6,073 — 5,752 599 6,351 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 June 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 2,349 $ — $ 3,028 $ 2 $ 3,030 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 June 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 1,265 $ — $ 1,279 $ 102 $ 1,381 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 June 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 1,180 $ — $ 1,083 $ 301 $ 1,384 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 of $200 million , $69 million , $48 million , $14 million , $8 million , $30 million , $10 million , and $6 million for Exelon, Generation, ComEd, PECO, BGE, Pepco, DPL and ACE, respectively, as of June 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 of $7 million , $1 million , and $6 million for Exelon, ComEd and BGE, respectively, as of June 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 six months ended June 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 June 30, 2016 and December 31, 2015 : Generation Exelon As of June 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) $ 42 $ — $ — $ — $ 42 $ 1,311 $ — $ — $ — $ 1,311 NDT fund investments Cash equivalents (b) 381 12 — — 393 381 12 — — 393 Equities 3,205 215 1 1,908 5,329 3,205 215 1 1,908 5,329 Fixed income Corporate debt — 1,910 249 — 2,159 — 1,910 249 — 2,159 U.S. Treasury and agencies 1,452 29 — — 1,481 1,452 29 — — 1,481 Foreign governments — 44 — — 44 — 44 — — 44 State and municipal debt — 285 — — 285 — 285 — — 285 Other (c) — 60 — 399 459 — 60 — 399 459 Fixed income subtotal 1,452 2,328 249 399 4,428 1,452 2,328 249 399 4,428 Middle market lending — — 465 — 465 — — 465 — 465 Private equity — — — 124 124 — — — 124 124 Real estate — — — 46 46 — — — 46 46 NDT fund investments subtotal (d) 5,038 2,555 715 2,477 10,785 5,038 2,555 715 2,477 10,785 Pledged assets for Zion Station decommissioning Cash equivalents 15 — — — 15 15 — — — 15 Equities — 6 — — 6 — 6 — — 6 Fixed income U.S. Treasury and agencies 23 2 — — 25 23 2 — — 25 Corporate debt — 9 — — 9 — 9 — — 9 Generation Exelon As of June 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 23 11 — — 34 23 11 — — 34 Middle market lending — — 25 81 106 — — 25 81 106 Pledged assets for Zion Station (e) 38 17 25 81 161 38 17 25 81 161 Rabbi trust investments Cash equivalents 8 — — — 8 81 — — — 81 Mutual funds 18 — — — 18 49 — — — 49 Fixed income — — — — — — 14 — — 14 Life insurance contracts — 17 — — 17 — 63 20 — 83 Rabbi trust investments subtotal 26 17 — — 43 130 77 20 — 227 Commodity derivative assets Economic hedges 1,342 3,087 1,506 — 5,935 1,343 3,087 1,506 — 5,936 Proprietary trading 25 71 31 — 127 25 71 31 — 127 Effect of netting and allocation of collateral (f) (1,308 ) (2,733 ) (779 ) — (4,820 ) (1,309 ) (2,733 ) (779 ) — (4,821 ) Commodity derivative assets subtotal 59 425 758 — 1,242 59 425 758 — 1,242 Interest rate and foreign currency derivative assets Derivatives designated as hedging instruments — — — — — — 47 — — 47 Economic hedges — 28 — — 28 — 28 — — 28 Proprietary trading 10 1 — — 11 10 1 — — 11 Effect of netting and allocation of collateral (7 ) (16 ) — — (23 ) (7 ) (16 ) — — (23 ) Interest rate and foreign currency derivative assets subtotal 3 13 — — 16 3 60 — — 63 Other investments — — 37 — 37 — — 37 — 37 Total assets 5,206 3,027 1,535 2,558 12,326 6,579 3,134 1,555 2,558 13,826 Liabilities Commodity derivative liabilities Economic hedges (1,456 ) (3,089 ) (1,013 ) — (5,558 ) (1,456 ) (3,089 ) (1,234 ) — (5,779 ) Proprietary trading (24 ) (73 ) (34 ) — (131 ) (24 ) (73 ) (34 ) — (131 ) Effect of netting and allocation of collateral (f) 1,431 3,012 898 — 5,341 1,431 3,012 898 — 5,341 Commodity derivative liabilities subtotal (49 ) (150 ) (149 ) — (348 ) (49 ) (150 ) (370 ) — (569 ) Interest rate and foreign currency derivative liabilities Derivatives designated as hedging instruments — (21 ) — — (21 ) — (23 ) — — (23 ) Economic hedges — (19 ) — — (19 ) — (19 ) — — (19 ) Proprietary trading (9 ) — — — (9 ) (9 ) — — — (9 ) Effect of netting and allocation of collateral 10 16 — — 26 10 16 — — 26 Interest rate and foreign currency derivative liabilities subtotal 1 (24 ) — — (23 ) 1 (26 ) — — (25 ) Deferred compensation obligation — (30 ) — — (30 ) — (127 ) — — (127 ) Total liabilities (48 ) (204 ) (149 ) — (401 ) (48 ) (303 ) (370 ) — (721 ) Total net assets $ 5,158 $ 2,823 $ 1,386 $ 2,558 $ 11,925 $ 6,531 $ 2,831 $ 1,185 $ 2,558 $ 13,105 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 $332 million million and $329 million at June 30, 2016 and December 31, 2015 and restricted cash of $97 million and $121 million at June 30, 2016 and December 31, 2015 . Exelon excludes cash of $423 million and $763 million at June 30, 2016 and December 31, 2015 and restricted cash of $136 million and $178 million at June 30, 2016 and December 31, 2015 and includes long term restricted cash of $22 million at June 30, 2016 , which is reported in other deferred debits on the balance sheet. (b) Includes $71 million and $52 million of cash received from outstanding repurchase agreements at June 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 $(16) million and $(8) million , which have a total notional amount of $1,303 million and $1,236 million at June 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 $(48) million and $(3) million at June 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 June 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 $123 million , $279 million and $119 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of June 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 June 30, 2016 and December 31, 2015 : ComEd PECO BGE As of June 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) $ 700 $ — $ — $ 700 $ 184 $ — $ — $ 184 $ 20 $ — $ — $ 20 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 700 — — 700 191 11 — 202 24 — — 24 Liabilities Deferred compensation obligation — (8 ) — (8 ) — (10 ) — (10 ) — (4 ) — (4 ) Mark-to-market derivative liabilities (b) — — (221 ) (221 ) — — — — — — — — Total liabilities — (8 ) (221 ) (229 ) — (10 ) — (10 ) — (4 ) — (4 ) Total net assets (liabilities) $ 700 $ (8 ) $ (221 ) $ 471 $ 191 $ 1 $ — $ 192 $ 24 $ (4 ) $ — $ 20 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 $ 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 $36 million and $38 million at June 30, 2016 and December 31, 2015 and restricted cash of $2 million and $2 million at June 30, 2016 and December 31, 2015 . PECO excludes cash of $22 million and $27 million at June 30, 2016 and December 31, 2015 . BGE excludes cash of $5 million and $6 million at June 30, 2016 and December 31, 2015 and restricted cash of $2 million and $2 million at June 30, 2016 and December 31, 2015 and includes long term restricted cash of $3 million at June 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 $18 million and $203 million , respectively, at June 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 June 30, 2016 and December 31, 2015 : Successor Predecessor As of June 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) $ 344 $ — $ — $ 344 $ 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 20 42 — 27 19 46 Rabbi trust investments subtotal 73 36 20 129 12 42 19 73 Total assets 417 36 20 473 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 $ 417 $ 8 $ 20 $ 445 $ 54 $ 12 $ 37 $ 103 Pepco DPL ACE As of June 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) $ 155 $ — $ — $ 155 $ 12 $ — $ — $ 12 $ 176 $ — $ — $ 176 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 20 42 — — — — — — — — Rabbi trust investments subtotal 43 36 20 99 — — — — — — — — Total assets 198 36 20 254 12 — — 12 176 — — 176 Liabilities Deferred compensation obligation — (5 ) — (5 ) — (1 ) — (1 ) — — — — Total liabilities — (5 ) — (5 ) — (1 ) — (1 ) — — — — Total net assets (liabilities) $ 198 $ 31 $ 20 $ 249 $ 12 $ (1 ) $ — $ 11 $ 176 $ — $ — $ 176 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 $13 million and $16 million at June 30, 2016 and December 31, 2015 and includes long term restricted cash of $19 million and $18 million at June 30, 2016 and December 31, 2015 which is reported in other deferred debits on the balance sheet. Pepco excludes cash of $5 million and $5 million at June 30, 2016 and December 31, 2015 . DPL excludes cash of $4 million and $5 million at June 30, 2016 and December 31, 2015 . ACE excludes cash of $4 million and $3 million at June 30, 2016 and December 31, 2015 and includes long term restricted cash of $19 million and $18 million at June 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 six months ended June 30, 2016 and 2015 : Successor Generation ComEd PHI Exelon Three Months Ended June 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 March 31, 2016 $ 684 $ 25 $ 1,047 $ 36 $ 1,792 $ (265 ) $ 20 $ — $ 1,547 Total realized / unrealized gains (losses) Included in net income 4 — (428 ) (b) — (424 ) — 1 — (423 ) Included in noncurrent payables to affiliates 8 — — — 8 — — (8 ) — Included in payable for Zion Station decommissioning — — — — — — — — — Included in regulatory assets — — — — — 44 — 8 52 Change in collateral — — (32 ) — (32 ) — — — (32 ) Purchases, sales, issuances and settlements Purchases 85 — 23 1 109 — — — 109 Sales (1 ) — (1 ) — (2 ) — — — (2 ) Issuances — — — — — — (1 ) — (1 ) Settlements (65 ) — — — (65 ) — — — (65 ) Transfers into Level 3 — — — — — — — — — Transfers out of Level 3 — — — — — — — — Balance at June 30, 2016 $ 715 $ 25 $ 609 $ 37 $ 1,386 $ (221 ) $ 20 $ — $ 1,185 The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of June 30, 2016 $ 3 $ — $ (264 ) $ — $ (261 ) $ 1 $ — $ (260 ) Successor Generation ComEd PHI (c) Exelon Six Months Ended June 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 6 — (434 ) (b) — (428 ) — 1 — (427 ) Included in noncurrent payables to affiliates 12 — — — 12 — — (12 ) — Included in payable for Zion Station decommissioning — 2 — — 2 — — — 2 Included in regulatory assets/liabilities — — — — — 26 — 12 38 Change in collateral — — (82 ) — (82 ) — — — (82 ) Purchases, sales, issuances and settlements Purchases 119 1 82 4 206 — — — 206 Sales (1 ) — (3 ) — (4 ) — — — (4 ) Issuances — — — — — — (1 ) — (1 ) Settlements (91 ) — — — (91 ) — — — (91 ) Transfers into Level 3 — — 2 — 2 — — — 2 Transfers out of Level 3 — — (7 ) — (7 ) — — — (7 ) Balance as of June 30, 2016 $ 715 $ 25 $ 609 $ 37 $ 1,386 $ (221 ) $ 20 $ — $ 1,185 The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of June 30, 2016 $ 4 $ — $ (45 ) $ — $ (41 ) $ — $ 1 $ — $ (40 ) ___________________ (a) Includes $40 million of increases in fair value and realized losses due to settlements of $4 million recorded in purchased power expense associated with floating-to-fixed energy swap contracts with unaffiliated suppliers for the three months ended June 30, 2016 . Includes $ 15 million of increases in fair value and realized losses due to settlements of $ 11 million for the six months ended June 30, 2016 . (b) Includes a reduction for the reclassification of $164 million and $389 million of realized gains due to the settlement of derivative contracts recorded in results of operations for the three and six months ended June 30, 2016 , respectively. (c) Successor period represents activity from March 24, 2016 through June 30, 2016 . See tables below for PHI's predecessor periods, as well as activity for Pepco and DPL for the three and six months ended June 30,

Derivative Financial Instrument

Derivative Financial Instruments (All Registrants)	6 Months Ended
	Jun. 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 June 30, 2016 , the proportion of expected generation hedged for the major reportable segments is 97% - 100% , 78% - 81% and 47% - 50% 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 2015 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 2015 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 30% 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 1,289 GWhs and 2,509 GWhs for the three and six months ended June 30, 2016 , respectively, and 1,657 GWhs and 3,465 GWhs for the three and six months ended June 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 June 30, 2016 , Exelon had $800 million of notional amounts of fixed-to-floating hedges outstanding, and Exelon and Generation had $764 million and $674 million of notional amounts of floating-to-fixed hedges outstanding, respectively. 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 $3 million decrease in Exelon Consolidated pre-tax income for the six months ended June 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 June 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) $ — $ 14 $ 6 $ (11 ) $ 9 $ — $ 9 Mark-to-market derivative assets (noncurrent assets) — 14 5 (12 ) 7 47 54 Total mark-to-market derivative assets — 28 11 (23 ) 16 47 63 Mark-to-market derivative liabilities (current liabilities) (8 ) (9 ) (4 ) 12 (9 ) — (9 ) Mark-to-market derivative liabilities (noncurrent liabilities) (13 ) (10 ) (5 ) 14 (14 ) (2 ) (16 ) Total mark-to-market derivative liabilities (21 ) (19 ) (9 ) 26 (23 ) (2 ) (25 ) Total mark-to-market derivative net assets (liabilities) $ (21 ) $ 9 $ 2 $ 3 $ (7 ) $ 45 $ 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. 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 June 30, Income Statement Location 2016 2015 2016 2015 Gain (loss) on Swaps Gain (loss) on Borrowings Exelon Interest expense $ 5 $ (11 ) $ (1 ) $ 16 Six Months Ended June 30, Income Statement Location 2016 2015 2016 2015 Gain (loss) on Swaps Gain (loss) on Borrowings Generation Interest expense (a) $ — $ (1 ) $ — $ — Exelon Interest expense 22 (1 ) (16 ) 9 __________ (a) For the six months ended June 30, 2015 , the loss on Generation swaps included $1 million realized in earnings with an immaterial amount excluded from hedge effectiveness testing. At June 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 $47 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 six months ended June 30, 2016 , the impact on the results of operations as a result of ineffectiveness from fair value hedges was a $4 million and a $6 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 the anticipated issuance of debt. The swaps are designated as cash flow hedges. At June 30, 2016 , Exelon had a $1 million derivative liability related to the swaps. 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 $497 million as of June 30, 2016 and expire in 2019. The swap was designated as a cash flow hedge in the fourth quarter of 2014. At June 30, 2016 , the subsidiary had a $18 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 $177 million as of June 30, 2016 and expire in 2020. The swaps are designated as cash flow hedges. At June 30, 2016 , the subsidiary had a $4 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 six months ended June 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 June 30, 2016 , Generation had immaterial notional amounts of interest rate derivative contracts to economically hedge risk associated with the interest rate component of commodity positions and $100 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 June 30, 2016 and December 31, 2015 , $10 million and $3 million of cash collateral 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 June 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) $ 4,089 $ 99 $ (3,438 ) $ 750 $ — $ 1 $ (1 ) $ — $ — $ 750 Mark-to-market derivative assets (noncurrent assets) 1,846 28 (1,382 ) 492 — — — — — 492 Total mark-to-market derivative assets 5,935 127 (4,820 ) 1,242 — 1 (1 ) — — 1,242 Mark-to-market derivative liabilities (current liabilities) (3,797 ) (94 ) 3,766 (125 ) (18 ) — — — — (143 ) Mark-to-market derivative liabilities (noncurrent liabilities) (1,761 ) (37 ) 1,575 (223 ) (203 ) — — — — (426 ) Total mark-to-market derivative liabilities (5,558 ) (131 ) 5,341 (348 ) (221 ) — — — — (569 ) Total mark-to-market derivative net assets (liabilities) $ 377 $ (4 ) $ 521 $ 894 $ (221 ) $ 1 $ (1 ) $ — $ — $ 673 ______ (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

Debt and Credit Agreements (All

Debt and Credit Agreements (All Registrants)	6 Months Ended
	Jun. 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 June 30, 2016 and December 31, 2015 : Commercial Paper Borrowings June 30, 2016 December 31, 2015 ComEd $ 35 $ 294 BGE 208 210 PHI Corporate — 484 Pepco — 64 DPL — 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, 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 July 28, 2016. 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% . As of June 30, 2016 , $10 million was outstanding under each note. The $10 million note outstanding between Generation and CENG is eliminated in consolidation and therefore not reflected in Exelon's or Generation's Consolidated Balance Sheets. The $10 million note with EDF is reflected in Exelon's and Generation's Consolidated Balance Sheet within Short-term borrowings. On July 25, 2016, CENG paid off the outstanding $10 million balance 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 lines 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 June 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 six months ended June 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 $ 63 Albany Green Energy biomass generation development Generation Energy Efficiency Project Financing 3.17 % February 1, 2037 $ 16 Funding to install energy conservation measures in Brooklyn, NY Generation Energy Efficiency Project Financing 3.90 % February 1, 2018 $ 7 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. Pepco Energy Efficiency Project Financing 3.30 % August 15, 2017 $ 1 Funding to install energy conservation measures for the DOE Germantown project 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)	6 Months Ended
	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes (Exelon, Generation, ComEd, PECO and BGE)	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 June 30, 2016 Successor Exelon Generation (e) ComEd PECO BGE (f) 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 2.3 (116.7) 4.8 0.3 2.0 6.1 3.5 4.8 5.9 Qualified nuclear decommissioning trust fund income 5.7 591.2 — — — — — — — Domestic production activities deduction — — — — — — — — — Health care reform legislation — — — — — — — — — Amortization of investment tax credit, net deferred taxes (1.8) (157.8) (0.2) (0.1) (0.4) (0.3) (0.1) (0.6) (1.6) Plant basis differences (d) (6.9) — (0.4) (11.3) (20.6) (7.0) (5.7) (3.5) (7.1) Production tax credits and other credits (5.8) (603.0) — — — — — — — Noncontrolling interests 0.9 94.4 — — — — — — — Statute of limitations expiration (1.7) (410.8) — — — — — — — Merger expenses 0.2 — — — — 1.0 0.2 3.1 — Other (c) (3.3) (52.3) (0.6) (5.2) (1.0) 1.0 (1.0) 1.2 7.8 Effective income tax rate 24.6% (620.0)% 38.6% 18.7% 15.0% 35.8% 31.9% 40.0% 40.0% Three Months Ended June 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 3.9 3.4 5.6 1.4 5.3 5.3 5.0 5.0 9.9 Qualified nuclear decommissioning trust fund income (1.0) (1.7) — — — — — — — Domestic production activities deduction (2.0) (3.4) — — — — — — — Health care reform legislation — — — — 0.1 — — — — Amortization of investment tax credit, net deferred taxes (0.6) (0.9) (0.3) (0.1) (0.2) (0.3) — (1.0) (0.2) Plant basis differences (1.0) — (0.1) (9.0) (0.5) (7.3) (8.3) (4.2) (0.1) Production tax credits and other credits (1.3) (2.2) — — — — — — — Noncontrolling interests (0.4) (0.6) — — — — — — — Other 1.4 2.0 0.5 0.5 0.8 1.1 (1.7) 3.7 (4.6) Effective income tax rate 34.0% 31.6% 40.7% 27.8% 40.5% 33.8% 30.0% 38.5% 40.0% Successor Predecessor Six Months Ended June 30, 2016 March 24, 2016 to June 30, 2016 January 1, 2016 to March 23, 2016 Exelon Generation ComEd PECO BGE Pepco (a) 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) 0.8 2.6 4.9 0.7 4.6 (9.5) (5.2) 5.9 5.2 11.9 Qualified nuclear decommissioning trust fund income 5.6 9.8 — — — — — — — — Domestic production activities deduction — — — — — — — — — — Health care reform legislation — — — — — — — — — — Amortization of investment tax credit, including deferred taxes on basis difference (1.7) (2.5) (0.2) (0.1) (0.1) 0.1 0.4 0.1 0.1 (0.9) Plant basis differences (d) (6.3) — (0.3) (10.2) (4.5) 12.6 2.0 1.0 1.7 (13.5) Production tax credits and other credits (5.5) (9.6) — — — — — — — — Noncontrolling interests 0.7 1.2 — — — — — — — — Statute of limitations expiration (1.0) (3.9) — — — — — — — Merger expenses 14.5 — — — — (36.1) (30.5) (17.7) (18.9) 11.1 Other (c) (2.8) (3.8) (0.1) (2.4) 0.1 (0.5) (0.1) (0.1) — 3.6 Effective income tax rate 39.3% 28.8% 39.3% 23.0% 35.1% 1.6% 1.6% 24.2% 23.1% 47.2% Six Months Ended June 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 3.2 3.0 5.3 1.3 5.3 6.4 4.1 5.5 5.5 Qualified nuclear decommissioning trust fund income 0.6 0.9 — — — — — — — Domestic production activities deduction (2.1) (3.4) — — — — — — — Health care reform legislation — — — — 0.2 — — — — Amortization of investment tax credit, including deferred taxes on basis difference (0.8) (1.1) (0.3) (0.1) (0.1) (0.4) — (0.4) (0.9) Plant basis differences (1.1) — (0.2) (7.5) (0.3) (6.1) (8.2) (1.5) (1.7) Production tax credits and other credits (1.6) (2.5) — — — — — — — Noncontrolling interests (0.6) (0.8) — — — — — — — Other 0.8 0.6 0.4 0.2 — (0.3) (0.3) 0.8 (0.4) Effective income tax rate 33.4% 31.7% 40.2% 28.9% 40.1% 34.6% 30.6% 39.4% 37.5% (a) Pepco, DPL and ACE recognized a loss before income taxes for the six months ended June 30, 2016 , and PHI recognized a loss before income taxes for the period of March 24, 2016, through June 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. (d) At BGE, includes a cumulative adjustment related to a regulatory asset. (e) The effective tax rate for the three months ended June 30, 2016 , is disproportionately impacted due to the decline in pre-tax GAAP earnings as compared to the changes in tax credits and other reconciling items. In three months ended June 30, 2016 , due to the expiration of a statute of limitations, Generation recorded an income tax benefit of $16 million. The statute of limitations expired in the third quarter of 2015; therefore, this represents an out of period adjustment. (f) The effective tax rate for the quarter is disproportionately impacted due to the decline in pre-tax GAAP earnings and changes in other reconciling items. Accounting for Uncertainty in Income Taxes The Registrants have the following unrecognized tax benefits as of June 30, 2016 and December 31, 2015 : Successor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE June 30, 2016 $ 963 $ 531 $ (12 ) $ — $ 120 $ 181 $ 95 $ 39 $ 24 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 June 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 $190 million , $159 million , $87 million , $36 million and $24 million , respectively. Reasonably possible the total amount of unrecognized tax benefits could significantly increase or decrease within 12 months after the reporting date Like-Kind Exchange As of June 30, 2016 , Exelon and ComEd have approximately $75 million and $(12) million of unrecognized state income tax benefits that could significantly decrease and increase, respectively, within the 12 months after the reporting date as a result of a decision or settlement in the like-kind exchange litigation described below. These unrecognized tax benefits, if recognized, would decrease Exelon’s effective tax rate by $75 million and increase ComEd’s effective tax rate by $12 million . Settlement of Income Tax Audits and Litigation As of June 30, 2016 , Exelon, Generation, BGE, PHI, Pepco, and DPL have approximately $300 million , $ 67 million , $120 million , $ 113 million , $ 71 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, Generation, PHI, and Pepco have $ 102 million , $ 67 million , $ 35 million , $ 13 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 has been unable to reach agreement with the IRS regarding the dispute over the like-kind exchange position. The IRS has asserted that the Exelon purchase and leaseback transaction is 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 has asserted that the sale of the fossil plants followed by the purchase and leaseback of the municipal owned generation facilities does not qualify as a like-kind exchange and the gain on the sale is fully subject to tax. The IRS has also asserted a penalty of approximately $90 million for a substantial understatement of tax. Exelon disagrees with the IRS and continues to believe that its like-kind exchange transaction is not the same as or substantially similar to a SILO. Although Exelon has been and remains willing to settle the disagreement on terms commensurate with the hazards of litigation, Exelon does not believe a settlement is likely. Because Exelon believed, as of December 31, 2012, that it is more-likely-than-not that Exelon would prevail in litigation, Exelon and ComEd had no liability for unrecognized tax benefits with respect to the like-kind exchange position. On January 9, 2013, the U.S. Court of Appeals for the Federal Circuit reversed the U.S. Court of Federal Claims and reached a decision for the government in Consolidated Edison v. United States. The Court disallowed Consolidated Edison’s deductions stemming from its participation in a LILO transaction that the IRS also has characterized as a tax shelter. In accordance with applicable accounting standards, Exelon is required to assess whether it is more-likely-than-not that it will prevail in litigation. Exelon continues to believe that its transaction is not a SILO and that it has a strong case on the merits. However, in light of the Consolidated Edison decision and Exelon’s current determination that settlement is unlikely, Exelon has concluded that subsequent to December 31, 2012, it is no longer more-likely-than-not that its position will be sustained. As a result, in the first quarter of 2013 Exelon recorded a non-cash charge to earnings of approximately $265 million , which represents 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 intends to hold ComEd harmless from any unfavorable impacts of the after-tax interest amounts on ComEd’s equity. As such, ComEd recorded on its consolidated balance sheet as of March 31, 2013, a $172 million receivable and non-cash equity contributions from Exelon. Exelon and ComEd will continue to accrue interest on the unpaid tax liabilities related to the uncertain tax position, and the charges arising from future interest accruals are not expected to be material to the annual operating earnings of Exelon or ComEd. In addition, ComEd will continue to record non-cash equity contributions from Exelon in the amount of the net after-tax interest charges attributable to ComEd in connection with the like-kind exchange position. Exelon continues to believe that it is unlikely that the IRS's assertion of penalties will ultimately be sustained and therefore no liability for the penalty has been recorded. 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. While the Tax Court could reach its decision as early as 2016, the litigation could take three to five years if an appeal is necessary. Decisions in the Tax Court are not controlled by the Federal Circuit’s decision in Consolidated Edison. In the event of a fully successful IRS challenge to Exelon’s like-kind exchange position, as of June 30, 2016 , potential tax of $ 460 million and after-tax interest of $ 310 million , exclusive of penalties, could become payable (net of a $ 65 million deposit made to the IRS in 2015). Of the above amounts, approximately $275 million would be attributable to ComEd after consideration of Exelon’s agreement to hold ComEd harmless. Interest will continue to accrue until such time as payment is made. An appeal of an adverse decision in the Tax Court would necessitate either the posting of a bond or the payment of the tax and interest for the tax years before the court. 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 $360 million . As a result of the lease terminations, any remaining tax gain related to the LKE position taken in 1999 will no longer be deferred. In the event of a successful outcome in the litigation, Exelon will not be required to pay the after-tax interest described in the preceding paragraph ($ 310 million as of June 30, 2016 ) but will be required to report the remaining $ 460 million of tax due on the transaction in Exelon's 2014 and 2016 tax years. Of that approximately $ 230 million is attributable to ComEd. The tax liabilities from the terminations will not result in a current year cash outflow due to the utilization of net operating losses and tax credit carryforwards. Long-Term State Tax Apportionment (Exelon, Generation and PHI) Exelon and Generation 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 and Generation 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)	6 Months Ended
	Jun. 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 generally updates its ARO annually during the third quarter, 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 June 30, 2016 : Nuclear decommissioning ARO at December 31, 2015 (a) $ 8,246 Accretion expense 215 Net increase due to changes in, and timing of, estimated cash flows 444 Costs incurred to decommission retired plants (2 ) Nuclear decommissioning ARO at June 30, 2016 (a) $ 8,903 _________ (a) Includes $11 million and $7 million for the current portion of the ARO at June 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 six months ended June 30, 2016 , Generation’s nuclear ARO increased by approximately $ 657 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 the 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 June 30, 2016 and December 31, 2015 , Exelon and Generation had NDT fund investments totaling $10,737 million and $10,342 million , respectively. The following table provides unrealized gains on NDT funds for the three and six months ended June 30, 2016 and 2015 : Exelon and Generation Exelon and Generation Three Months Ended June 30, Six Months Ended June 30, 2016 2015 2016 2015 Net unrealized gains (losses) on decommissioning trust funds — Regulatory Agreement Units (a) $ 52 $ (133 ) $ 131 $ (85 ) Net unrealized gains (losses) on decommissioning trust funds — Non-Regulatory Agreement Units (b)(c) 48 (96 ) 100 (56 ) _________ (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 $1 million of net unrealized gain related to the Zion Station pledged assets for the three months ended June 30, 2016 . Excludes $3 million and $9 million of net unrealized gain related to the Zion Station pledged assets for the six months ended June 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 $86 million which is included within the nuclear decommissioning ARO at June 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 June 30, 2016 and December 31, 2015 : Exelon and Generation June 30, 2016 December 31, 2015 Carrying value of Zion Station pledged assets $ 161 $ 206 Payable to Zion Solutions (a) 148 189 Current portion of payable to Zion Solutions (b) 94 99 Cumulative withdrawals by Zion Solutions to pay decommissioning costs (c) 834 786 _________ (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)	6 Months Ended
	Jun. 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 six months ended June 30, 2016 and 2015 . Pension Benefits Other Postretirement Benefits 2016 2015 2016 2015 Service cost $ 91 $ 81 $ 28 $ 29 Interest cost 212 178 48 42 Expected return on assets (292 ) (256 ) (42 ) (37 ) Amortization of: Prior service cost (benefit) 4 4 (47 ) (44 ) Actuarial loss 142 142 16 21 Net periodic benefit cost $ 157 $ 149 $ 3 $ 11 Pension Benefits Other Postretirement Benefits 2016 (a) 2015 2016 (a) 2015 Components of net periodic benefit cost: Service cost $ 170 $ 163 $ 54 $ 59 Interest cost 403 355 90 83 Expected return on assets (555 ) (513 ) (80 ) (75 ) Amortization of: Prior service cost (benefit) 7 7 (91 ) (88 ) Actuarial loss 269 285 30 41 Net periodic benefit cost $ 294 $ 297 $ 3 $ 20 _______ (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 June 30, 2015 Six Months Ended June 30, 2015 January 1, 2016 to March 23, 2016 Three Months Ended June 30, 2015 Six Months Ended June 30, 2015 Service cost $ 12 $ 14 $ 28 $ 1 $ 1 $ 3 Interest cost 26 27 54 6 6 12 Expected return on assets (30 ) (35 ) (70 ) (5 ) (5 ) (11 ) Amortization of: Prior service cost (benefit) — 1 1 (3 ) (3 ) (6 ) Actuarial loss 14 17 33 2 1 4 Net periodic benefit cost $ 22 $ 24 $ 46 $ 1 $ — $ 2 The amounts below represent Exelon's, Generation's, ComEd's, PECO's, BGE'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 six months ended June 30, 2016 and 2015 . Three Months Ended June 30, Six Months Ended June 30, Pension and Other Postretirement Benefit Costs 2016 2015 2016 2015 Exelon $ 160 $ 160 $ 297 $ 317 Generation 55 68 109 133 ComEd 42 51 83 103 PECO 8 10 17 19 BGE 18 17 33 33 BSC (a) 10 14 24 29 Pepco (b) 7 7 16 15 DPL (b) 4 4 9 8 ACE (b) 4 4 8 8 PHISCO (a)(b) 12 9 21 17 Successor Predecessor Successor Predecessor Pension and Other Postretirement Benefit Costs Three Months Ended June 30, 2016 Three Months Ended June 30, 2015 March 24, 2016 to June 30, 2016 January 1, 2016 to March 23, 2016 Six Months Ended June 30, 2015 PHI $ 27 $ 24 $ 31 $ 23 $ 48 _________ (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 six months ended June 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 six months ended June 30, 2016 and 2015 : Three Months Ended June 30, Six Months Ended June 30, Savings Plan Matching Contributions 2016 2015 2016 2015 Exelon $ 30 $ 38 $ 56 $ 60 Generation 13 20 25 33 ComEd 7 8 13 13 PECO 2 3 4 4 BGE 2 3 3 5 BSC (a) 2 4 7 5 Pepco (b) 1 1 2 2 DPL (b) — 1 1 1 PHISCO (a)(b) 2 1 3 3 ACE (b) 1 1 1 1 Successor Predecessor Successor Predecessor Savings Plan Matching Contributions Three Months Ended June 30, 2016 Three Months Ended June 30, 2015 March 24, 2016 to June 30, 2016 January 1, 2016 to March 23, 2016 Six Months Ended June 30, 2015 PHI $ 4 $ 4 $ 4 $ 3 $ 7 _________ (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 six months ended June 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 six months ended June 30, 2016 .

Severance (All Registrants)

Severance (All Registrants)	6 Months Ended
	Jun. 30, 2016
Restructuring Charges [Abstract]
Severance (Exelon, Generation, ComEd, PECO and BGE)	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 six months ended June 30, 2016 and 2015 , Exelon, Generation and ComEd recorded the following severance costs associated with these ongoing severance benefits within Operating and maintenance expense in their Consolidated Statements of Operations and Comprehensive Income. Exelon Generation (a) ComEd Three Months Ended June 30, 2016 $ 2 $ 1 $ 1 June 30, 2015 1 1 — Six Months Ended June 30, 2016 $ 4 $ 3 $ 1 June 30, 2015 21 21 — _______ (a) The amounts above for Generation include $1 million and $2 million for amounts billed by BSC through intercompany allocations for the three months ended June 30, 2016 and 2015 , respectively, and $2 million and $4 million for the six months ended June 30, 2016 and 2015 , respectively. The amounts above for ComEd include less than $1 million and $1 million billed by BSC through intercompany allocations for the three and six months ended June 30, 2016 , respectively. 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. In June 2016, Exelon and Generation recognized severance benefit costs of $46 million related to expected employee severances resulting from the plant retirements within Operating and maintenance expense in their Consolidated Statements of Operations and Comprehensive Income. The final amount of severance cost will ultimately depend on the specific employees severed. The $46 million of costs for Generation include $3 million for amounts billed by BSC through intercompany allocations for the three and six months ended June 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 second quarter were immaterial. The final amount of the charge will ultimately depend on the specific employees severed. For the six months ended June 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 Six Months Ended June 30, 2016 Severance benefits (a) $ 17 $ 12 $ 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 six months ended June 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 and six months ended June 30, 2016 , the Registrants recorded the following severance costs (benefits) 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 Three Months Ended June 30, 2016 Severance benefits (a) $ 2 $ (1 ) $ (1 ) $ — $ — $ 4 $ 2 $ 1 $ 1 Six Months Ended June 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 $(1) million , $(1) million , less than $1 million , less than $1 million , $2 million , $1 million and $1 million , respectively, for amounts billed by BSC and/or PHISCO through intercompany allocations for the three months ended June 30, 2016 , and $8 million , $2 million , $1 million , $1 million , $19 million , $11 million and $10 million for the six months ended June 30, 2016 . (b) Pepco established a regulatory asset of $9 million as of June 30, 2016, primarily for severance benefit costs related to the PHI merger. (c) DPL established a regulatory asset of $3 million as of June 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 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) 129 56 1 — — 54 1 1 — Payments (19 ) (4 ) (1 ) — — (11 ) — — — Balance at June 30, 2016 $ 145 $ 75 $ 3 $ — $ 1 $ 43 $ 1 $ 1 $ — ______________ (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 June 30, 2016 for PHI, Pepco, DPL and ACE.

Mezzanine Equity Mezzanine Equi

Mezzanine Equity Mezzanine Equity (Exelon, Generation and PHI)	6 Months Ended
	Jun. 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 six months ended June 30, 2016 : Balance at December 31, 2015 $ 28 Cash received from noncontrolling interests 52 Release of contingency (56 ) Balance at June 30, 2016 $ 24 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 Sheet. 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 , Statement 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)	6 Months Ended
	Jun. 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 six months ended June 30, 2016 and 2015 : Six Months Ended June 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 (4 ) — (2 ) 6 (7 ) (7 ) Amounts reclassified from AOCI (b) (3 ) — 69 — — 66 Net current-period OCI (7 ) — 67 6 (7 ) 59 Ending balance $ (26 ) $ 3 $ (2,498 ) $ (34 ) $ (10 ) $ (2,565 ) Generation (a) Beginning balance $ (21 ) $ 1 $ — $ (40 ) $ (3 ) $ (63 ) OCI before reclassifications (1 ) — — 6 (4 ) 1 Amounts reclassified from AOCI (b) (3 ) — — — — (3 ) Net current-period OCI (4 ) — — 6 (4 ) (2 ) Ending balance $ (25 ) $ 1 $ — $ (34 ) $ (7 ) $ (65 ) 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 ) Six Months Ended June 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 (10 ) — (29 ) (9 ) — (48 ) Amounts reclassified from AOCI (b) 19 — 87 — — 106 Net current-period OCI 9 — 58 (9 ) — 58 Ending balance $ (19 ) $ 3 $ (2,582 ) $ (28 ) $ — $ (2,626 ) Generation (a) Beginning balance $ (18 ) $ 1 $ — $ (19 ) $ — $ (36 ) OCI before reclassifications (6 ) 1 — (9 ) — (14 ) Amounts reclassified from AOCI (b) 3 — — — — 3 Net current-period OCI (3 ) 1 — (9 ) — (11 ) Ending balance $ (21 ) $ 2 $ — $ (28 ) $ — $ (47 ) 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) — — 4 — — 4 Net current-period OCI — — 4 — — 4 Ending balance $ (9 ) $ — $ (33 ) $ — $ — $ (42 ) ________ (a) All amounts are net of tax. 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 six months ended June 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 six months ended June 30, 2016 and 2015 . Three Months Ended June 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) (75 ) — Total before tax (56 ) — Tax benefit 22 — Net of tax $ (34 ) $ — Total Reclassifications for the period $ (34 ) $ — Comprehensive income Six Months Ended June 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) $ 38 $ — $ — Actuarial losses (b) (151 ) — (1 ) Total before tax (113 ) — (1 ) Tax benefit 44 — — Net of tax $ (69 ) $ — $ (1 ) Total Reclassifications $ (66 ) $ 3 $ (1 ) Comprehensive income Three Months Ended June 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 $ (2 ) $ (2 ) $ — Interest expense Total before tax (2 ) (2 ) — Tax expense — — — Net of tax $ (2 ) $ (2 ) $ — Comprehensive income Amortization of pension and other postretirement benefit plan items Prior service costs (b) $ 19 $ — $ — Actuarial losses (b) (90 ) — (3 ) Total before tax (71 ) — (3 ) Tax expense 27 — — Net of tax $ (44 ) $ — $ (3 ) Total Reclassifications for the period $ (46 ) $ (2 ) $ (3 ) Comprehensive income Six Months Ended June 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 (5 ) (5 ) — Interest expense Total before tax (29 ) (3 ) — Tax benefit 10 — — Net of tax $ (19 ) $ (3 ) $ — Comprehensive income Amortization of pension and other postretirement benefit plan items Prior service costs (b) $ 38 $ — $ — Actuarial losses (b) (180 ) — (5 ) Total before tax (142 ) — (5 ) Tax benefit 55 — 1 Net of tax $ (87 ) $ — $ (4 ) Total Reclassifications $ (106 ) $ (3 ) $ (4 ) 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 six months ended June 30, 2016 and 2015 : Three Months Ended June 30, Six Months Ended June 30, 2016 2015 2016 2015 Exelon Pension and non-pension postretirement benefit plans: Prior service benefit reclassified to periodic benefit cost $ 7 $ 8 $ 15 $ 15 Actuarial loss reclassified to periodic cost (30 ) (35 ) (60 ) (69 ) Pension and non-pension postretirement benefit plans valuation adjustment — — 1 17 Change in unrealized gain/(loss) on cash flow hedges 2 (2 ) 4 (6 ) Change in unrealized loss on equity investments 1 — 3 — Change in unrealized gain on marketable securities (1 ) 1 — 1 Total $ (21 ) $ (28 ) $ (37 ) $ (42 ) Generation Change in unrealized gain/(loss) on cash flow hedges $ 1 $ (1 ) $ 3 $ 1 Change in unrealized loss on equity investments 1 — 3 — Change in unrealized gain on marketable securities — — — 1 Total $ 2 $ (1 ) $ 6 $ 2 Predecessor PHI Three Months Ended January 1, 2016 to March 23, 2016 Six Months Ended June 30, 2015 Pension and non-pension postretirement benefit plans: Actuarial loss reclassified to periodic cost $ — $ — $ (1 )

Earnings Per Share and Equity (

Earnings Per Share and Equity (Exelon)	6 Months Ended
	Jun. 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 June 30, Six Months Ended June 30, Exelon 2016 2015 2016 2015 Net income attributable to common shareholders $ 267 $ 638 $ 440 $ 1,331 Weighted average common shares outstanding — basic 924 863 923 862 Assumed exercise and/or distributions of stock-based awards 2 3 3 4 Weighted average common shares outstanding — diluted 926 866 926 866 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 six months ended June 30, 2016 , respectively and 13 million and 15 million for three and six months ended June 30, 2015 , respectively. 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 under 1 million and 2 million for the three and six months ended June 30, 2016 , respectively, and 1 million for the three and six months ended June 30, 2015 . 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 June 30, 2016 . In 2008, Exelon management decided to defer indefinitely any share repurchases. Preference Stock Redemption (BGE) BGE has $190 million of cumulative preference stock that are redeemable at its option at any time 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. Following these redemptions, BGE has $90 million of cumulative preference stock outstanding.

Commitments and Contingencies (

Commitments and Contingencies (All Registrants)	6 Months Ended
	Jun. 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 $500 million to $600 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 June 30, 2016 , Exelon and Generation have incurred $ 402 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 June 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) $ 203 2017 22 2018 10 Total $ 235 ________ (a) The noncontrolling interests holder of 2015 ESA Investco, LLC will contribute up to $90 million in support of a portion of the remaining equity commitment. Commercial Commitments (All Registrants) The Registrants’ commercial commitments as of June 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) $ 1,651 $ 1,580 $ 16 $ 23 $ 2 $ 1 $ — $ — $ 1 Surety bonds (b) 1,055 964 10 9 10 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 5 7 5 Total commercial commitments $ 6,399 $ 5,589 $ 226 $ 210 $ 262 $ 37 $ 14 $ 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, $16 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 June 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 June 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 2020. • 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 2021. • 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 June 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: June 30, 2016 Total Environmental Investigation and Remediation Reserve Portion of Total Related to MGP Investigation and Remediation (a) Exelon $ 410 $ 311 Generation 66 — ComEd 277 275 PECO 35 33 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. 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 $11 million at June 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 August 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 $60 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 final 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 fall of 2016 to enable the EPA to propose a remedy for public comment by the end of 2016. 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 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 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, 57 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 $7 million which has been fully reserved and included in the table above as of June 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 environmental investigation and present cleanup recommendations at the site. In addition, the EPA is seeking recovery from the PRPs of $1.7 million for past cleanup and investigation costs at the site. On March 11, 2013, BGE and three other PRP’s signed an Administrative Settlement Agreement and Order on Consent with the EPA which requires the PRP’s to conduct a remedial investigation (RI) and feasibility study (FS) at the site to determine what, if any, are the appropriate and recommended cleanup activities for the site. The ultimate outcome of this proceeding is uncertain. Since the EPA has not selected a cleanup remedy and the allocatio

Supplemental Financial Informat

Supplemental Financial Information (All Registrants)	6 Months Ended
	Jun. 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 six months ended June 30, 2016 and 2015 : Three Months Ended June 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 $ 90 $ 90 $ — $ — $ — $ — $ — $ — $ — Non-regulatory agreement units 39 39 — — — — — — — Net unrealized gains on decommissioning trust funds Regulatory agreement units 52 52 — — — — — — — Non-regulatory agreement units 48 48 — — — — — — — Net unrealized gains on pledged assets Zion Station decommissioning 1 1 — — — — — — — Regulatory offset to decommissioning trust fund-related activities (b) (117 ) (117 ) — — — — — — — Total decommissioning-related activities 113 113 — — — — — — — Investment income 6 5 — — — — — — — Interest income related to uncertain income tax positions 4 — — — — — — — — AFUDC — Equity 15 — 1 2 5 7 5 1 1 Other 6 (1 ) 2 — — 4 1 2 1 Other, net $ 144 $ 117 $ 3 $ 2 $ 5 $ 11 $ 6 $ 3 $ 2 Successor Predecessor Six Months Ended June 30, 2016 March 24, 2016 to June 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 $ 122 $ 122 $ — $ — $ — $ — $ — $ — $ — $ — Non-regulatory agreement units 61 61 — — — — — — — — Net unrealized gains on decommissioning trust funds Regulatory agreement units 131 131 — — — — — — — — Non-regulatory agreement units 100 100 — — — — — — — — Net unrealized gains on pledged assets Zion Station decommissioning 3 3 — — — — — — — — Regulatory offset to decommissioning trust fund-related activities (b) (211 ) (211 ) — — — — — — — — Total decommissioning-related activities 206 206 — — — — — — — — Investment income (expense) 12 5 — (1 ) 2 (c) — — — — — Long-term lease income 4 — — — — — — — — — Interest income related to uncertain income tax positions 5 — — — — 1 — 1 — — AFUDC — Equity 24 — 3 4 9 9 2 3 8 7 Loss on debt extinguishment (3 ) (2 ) — — — — — — — Other 10 1 4 1 — 4 4 1 4 (11 ) Other, net $ 258 $ 210 $ 7 $ 4 $ 11 $ 14 $ 6 $ 5 $ 12 $ (4 ) Three Months Ended June 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 $ 93 $ 93 $ — $ — $ — $ — $ — $ — $ — Non-regulatory agreement units 74 74 — — — — — — — Net unrealized losses on decommissioning trust funds Regulatory agreement units (133 ) (133 ) — — — — — — — Non-regulatory agreement units (96 ) (96 ) — — — — — — — Regulatory offset to decommissioning trust fund-related activities (b) 28 28 — — — — — — — Total decommissioning-related activities (34 ) (34 ) — — — — — — — Investment income (expense) 1 — — (1 ) 1 (c) — — — — Long-term lease income 4 — — — — — — — — AFUDC — Equity 5 — 1 1 3 3 3 — — Other 7 3 4 1 — 9 5 2 1 Other, net $ (17 ) $ (31 ) $ 5 $ 1 $ 4 $ 12 $ 8 $ 2 $ 1 Six Months Ended June 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 $ 164 $ 164 $ — $ — $ — $ — $ — $ — $ — Non-regulatory agreement units 104 104 — — — — — — — Net unrealized losses on decommissioning trust funds Regulatory agreement units (85 ) (85 ) — — — — — — — Non-regulatory agreement units (56 ) (56 ) — — — — — — — Net unrealized gains on pledged assets Zion Station decommissioning 9 9 — — — — — — Regulatory offset to decommissioning trust fund-related activities (b) (78 ) (78 ) — — — — — — — Total decommissioning-related activities 58 58 — — — — — — — Investment income (expense) 4 1 — (1 ) 2 (c) — — — — Long-term lease income 8 — — — — — — — — Interest income related to uncertain income tax positions — 1 — — — — — — — AFUDC — Equity 11 — 1 3 7 7 6 — 1 Terminated interest rate swaps (d) (26 ) — — — — — — — — Other 9 2 8 1 (1 ) 14 7 5 2 Other, net $ 64 $ 62 $ 9 $ 3 $ 8 $ 21 $ 13 $ 5 $ 3 ____ (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) 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. (d) 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 six months ended June 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 June 30, 2016 Successor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Utility taxes $ 217 $ 27 $ 60 $ 32 $ 21 $ 77 $ 73 $ 4 $ — Successor Predecessor Six Months Ended June 30, 2016 March 24, 2016 to June 30, 2016 January 1, 2016 to March 23, 2016 Exelon Generation ComEd PECO BGE Pepco DPL ACE PHI PHI Utility taxes $ 369 $ 55 $ 119 $ 66 $ 45 $ 152 $ 9 $ — $ 84 $ 77 Three Months Ended June 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Utility taxes $ 132 $ 24 $ 55 $ 32 $ 21 $ 81 $ 77 $ 4 $ — Six Months Ended June 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Utility taxes $ 279 $ 51 $ 117 $ 67 $ 44 $ 166 $ 157 $ 9 $ — Supplemental Cash Flow Information The following tables provide additional information regarding the Registrants’ Consolidated Statements of Cash Flows for the six months ended June 30, 2016 and 2015 : Successor Predecessor Six Months Ended June 30, 2016 March 24, 2016 to June 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) $ 1,432 $ 674 $ 345 $ 121 $ 150 $ 85 $ 55 $ 40 $ 111 $ 94 Amortization of regulatory assets (a) 166 — 34 13 56 59 21 41 63 58 Amortization of intangible assets, net (a) 28 23 — — — — — — — — Amortization of energy contract assets and liabilities (b) (7 ) (7 ) — — — — — — — — Nuclear fuel (c) 557 557 — — — — — — — — ARO accretion (d) 220 220 — — — — — — — — Total depreciation, amortization, accretion and depletion $ 2,396 $ 1,467 $ 379 $ 134 $ 206 $ 144 $ 76 $ 81 $ 174 $ 152 Six Months Ended June 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Depreciation, amortization, accretion and depletion Property, plant and equipment (a) $ 1,087 $ 485 $ 312 $ 119 $ 143 $ 193 $ 81 $ 50 $ 38 Amortization of regulatory assets (a) 101 — 40 12 49 114 44 24 48 Amortization of intangible assets, net (a) 24 24 — — — — — — — Amortization of energy contract assets and liabilities (b) — 1 — — — — — — — Nuclear fuel (c) 552 552 — — — — — — — ARO accretion (d) 193 193 — — — — — — — Total depreciation, amortization, accretion and depletion $ 1,957 $ 1,255 $ 352 $ 131 $ 192 $ 307 $ 125 $ 74 $ 86 ________ (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 Six Months Ended June 30, 2016 March 24, 2016 to June 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 $ 297 $ 109 $ 83 $ 17 $ 33 $ 16 $ 9 $ 8 $ 31 $ 23 Loss from equity method investments 10 11 — — — — — — — — Provision for uncollectible accounts 51 13 18 10 3 8 8 10 7 16 Stock-based compensation costs 67 — — — — — — — — 3 Other decommissioning-related activity (a) (123 ) (123 ) — — — — — — — — Energy-related options (b) (17 ) (17 ) — — — — — — — — Amortization of regulatory asset related to debt costs 4 — 2 1 — 1 — — 1 1 Amortization of rate stabilization deferral 34 — — — 34 (2 ) 2 — — 5 Amortization of debt fair value adjustment (6 ) (6 ) — — — — — — — — Discrete impacts from EIMA (c) (21 ) — (21 ) — — — — — — — Amortization of debt costs 14 10 2 1 2 — — — — — Provision for excess and obsolete inventory 68 66 2 — — 1 1 1 — 1 Merger-related commitments (d)(e) 503 3 — — — 138 100 120 358 — Severance costs 122 50 — — — — — — 54 — Asset retirement costs — — — — — — 4 2 — — Lower of cost or market inventory adjustment 36 36 — — — — — — — — Other 17 17 (3 ) (2 ) (12 ) (4 ) (3 ) (3 ) (7 ) (3 ) Total other non-cash operating activities $ 1,056 $ 169 $ 83 $ 27 $ 60 $ 158 $ 121 $ 138 $ 444 $ 46 Non-cash investing and financing activities: Change in capital expenditures not paid $ (364 ) $ (317 ) $ (21 ) $ (12 ) $ 2 $ 11 $ (9 ) $ 6 $ (4 ) $ 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) — — — — — — — — 127 — 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 471 471 — — — — — — — — Indemnification of like-kind exchange position (g) — — 5 — — — — — — — Non-cash financing of capital projects 60 60 — — — — — — — — Six Months Ended June 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Other non-cash operating activities: Pension and non-pension postretirement benefit costs $ 317 $ 133 $ 103 $ 19 $ 33 $ 48 $ 15 $ 8 $ 8 Loss from equity method investments 2 3 — — — — — — — Provision for uncollectible accounts 80 11 35 24 11 30 9 12 9 Stock-based compensation costs 79 — — — — 6 — — — Other decommissioning-related activity (a) (50 ) (50 ) — — — — — — — Energy-related options (b) 27 27 — — — — — — — Amortization of regulatory asset related to debt costs — — — — — 2 1 — — Amortization of rate stabilization deferral 40 — — — 40 9 8 1 — Amortization of debt fair value adjustment (37 ) (6 ) — — — — — — — Discrete impacts from EIMA (c) 77 — 77 — — — — — — Amortization of debt costs 35 8 2 1 1 1 — — — Provision for excess and obsolete inventory — — — — — 1 — — — Lower of cost or market inventory adjustment 13 13 — — — — — — — Other (4 ) (5 ) 5 1 (9 ) 4 — 1 — Total other non-cash operating activities $ 579 $ 134 $ 222 $ 45 $ 76 $ 101 $ 33 $ 22 $ 17 Non-cash investing and financing activities: Indemnification of like-kind exchange position (g) — — 3 — — — — — — 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 June 30, 2016 and December 31, 2015 : Successor June 30, 2016 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Property, plant and equipment: Accumulated depreciation and amortization $ 17,340 (a) $ 9,179 (a) $ 3,785 $ 3,185 $ 3,161 $ 83 $ 2,995 $ 1,157 $ 998 Accounts receivable: Allowance for uncollectible accounts $ 314 $ 82 $ 74 $ 75 $ 33 $ 50 $ 16 $ 17 $ 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 $2,936 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 June 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 June 30, 2016 of $16 million consists of $1 million , $3 million and $12 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 June 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)	6 Months Ended
	Jun. 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 six months ended June 30, 2016 and 2015 is as follows: Three Months Ended June 30, 2016 and 2015 Successor Generation (a) ComEd PECO BGE PHI (b) Other (c) Intersegment Exelon Operating revenues (d) : 2016 Competitive businesses electric revenues $ 3,655 $ — $ — $ — $ — $ — $ (354 ) $ 3,301 Competitive businesses natural gas revenues 367 — — — — — — 367 Competitive businesses other revenues (433 ) — — — — — (1 ) (434 ) Rate-regulated electric revenues — 1,286 587 584 1,030 — (7 ) 3,480 Rate-regulated natural gas revenues — — 77 96 26 — (2 ) 197 Shared service and other revenues — — — — 10 398 (409 ) (1 ) 2015 Competitive businesses electric revenues $ 3,663 $ — $ — $ — $ — $ — $ (151 ) $ 3,512 Competitive businesses natural gas revenues 431 — — — — — — 431 Competitive businesses other revenues 138 — — — — — (1 ) 137 Rate-regulated electric revenues — 1,148 582 541 — — (1 ) 2,270 Rate-regulated natural gas revenues — — 79 87 — — (1 ) 165 Shared service and other revenues — — — — — 340 (341 ) (1 ) Intersegment revenues (e) : 2016 $ 355 $ 3 $ 2 $ 4 $ 10 $ 398 $ (771 ) $ 1 2015 152 1 — 1 — 340 (493 ) 1 Net income (loss): 2016 $ 28 $ 145 $ 100 $ 34 $ 52 $ (52 ) $ (1 ) $ 306 2015 390 99 70 47 — 28 (1 ) 633 Total assets: June 30, 2016 $ 46,897 $ 28,105 $ 10,586 $ 8,325 $ 20,921 $ 10,069 $ (12,125 ) $ 112,778 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 June 30, 2016 include revenue from sales to PECO of $64 million and sales to BGE of $135 million in the Mid-Atlantic region, and sales to ComEd of $13 million in the Midwest region. For the three months ended June 30, 2015 , intersegment revenues for Generation include revenue from sales to PECO of $49 million and sales to BGE of $97 million in the Mid-Atlantic region, and sales to ComEd of $6 million in the Midwest region. For the Successor period of three months ended June 30, 2016 , intersegment revenues for Generation include revenue from sales to Pepco of $88 million , sales to DPL of $43 million , and sales to ACE of $12 million in the Mid-Atlantic region. (b) Amounts included represent activity for the PHI's successor period, three months ended June 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 six months ended June 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 June 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 June 30, 2016 Three Months Ended June 30, 2015 Revenues (a) Intersegment Total Revenues (a)(c) Intersegment (c) Total (c) Mid-Atlantic $ 1,432 $ (16 ) $ 1,416 $ 1,364 $ (18 ) $ 1,346 Midwest 1,076 7 1,083 1,206 — 1,206 New England 352 (1 ) 351 367 — 367 New York 356 (10 ) 346 222 (4 ) 218 ERCOT 207 — 207 194 (2 ) 192 Other Power Regions 232 (9 ) 223 310 (21 ) 289 Total Revenues for Reportable Segments 3,655 (29 ) 3,626 3,663 (45 ) 3,618 Other (b) (66 ) 29 (37 ) 569 45 614 Total Generation Consolidated Operating Revenues $ 3,589 $ — $ 3,589 $ 4,232 $ — $ 4,232 __________ (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. Also includes a $9 million decrease and $17 million decrease to revenues for the amortization of intangible assets related to commodity contracts recorded at fair value for the three months ended June 30, 2016 and 2015 , respectively, unrealized mark-to-market losses of $615 million and gains of $25 million for the three months ended June 30, 2016 and 2015 , respectively, and elimination of intersegment revenues. (c) Exelon corrected an error in the June 30, 2015 balances within Intersegment Revenue and Revenue from external customers for an overstatement of $46 million of Intersegment Revenue for Reportable Segments for the three months ended June 30, 2015 , an understatement of Revenue from external customers for Reportable Segments of $46 million for the three months ended June 30, 2015 , an understatement of $46 million of Intersegment Revenue for Other for the three months ended June 30, 2015 , and an overstatement of Revenue from external customers for Other of $46 million for the three months ended June 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 June 30, 2016 Three Months Ended June 30, 2015 RNF (a) Intersegment RNF Total RNF RNF (a)(c) Intersegment RNF (c) Total RNF (c) Mid-Atlantic $ 830 $ (2 ) $ 828 $ 891 $ 1 $ 892 Midwest 724 4 728 750 (5 ) 745 New England 118 (8 ) 110 95 (7 ) 88 New York 270 (3 ) 267 138 7 145 ERCOT 111 (34 ) 77 91 (21 ) 70 Other Power Regions 123 (27 ) 96 113 (51 ) 62 Total Revenues net of purchased power and fuel for Reportable Segments 2,176 (70 ) 2,106 2,078 (76 ) 2,002 Other (b) (164 ) 70 (94 ) 305 76 381 Total Generation Revenues net of purchased power and fuel expense $ 2,012 $ — $ 2,012 $ 2,383 $ — $ 2,383 __________ (a) Includes purchases and sales from 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. Also includes a $12 million decrease and a $14 million decrease to RNF for the amortization of intangible assets related to commodity contracts for the three months ended June 30, 2016 and 2015 , respectively, unrealized mark-to-market losses of $304 million and gains of $235 million for the three months ended June 30, 2016 and 2015 , respectively, accelerated nuclear fuel amortization associated with nuclear decommissioning as discussed at Note 7 - Early Nuclear Plant Retirements of the Combined Notes to Consolidated Financial Statements of $9 million for the three months ended June 30, 2016 , and the elimination of intersegment revenue net of purchased power and fuel expense. (c) Exelon corrected an error in the June 30, 2015 balances within Intersegment RNF and RNF from external customers for an understatement of $6 million of Intersegment RNF for Reportable Segments for the three months ended June 30, 2015 , and an overstatement of $6 million of Intersegment RNF for Other for the three months ended June 30, 2015 . This also included an understatement of total RNF for Reportable Segments and an overstatement of total RNF for Other of $6 million for the three months ended June 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 June 30, 2016 - Successor Rate-regulated electric revenues $ 509 $ 255 $ 270 $ — $ (4 ) $ 1,030 Rate-regulated natural gas revenues — 26 — — — 26 Shared service and other revenues — — — 10 — 10 Three months ended June 30, 2015 - Predecessor Rate-regulated electric revenues $ 504 $ 246 $ 285 $ 59 $ — $ 1,094 Rate-regulated natural gas revenues — 25 — — — 25 Shared service and other revenues — — — — — — Intersegment revenues (e) : Three months ended June 30, 2016 - Successor $ 1 $ 2 $ 1 $ 10 $ (4 ) $ 10 Three months ended June 30, 2015 - Predecessor 1 2 1 — (4 ) — Net income (loss): Three months ended June 30, 2016 - Successor $ 49 $ 12 $ 3 $ (22 ) $ 10 $ 52 Three months ended June 30, 2015 - Predecessor 42 8 6 (3 ) — 53 Total assets: June 30, 2016 - Successor $ 7,099 $ 3,971 $ 3,461 $ 11,042 $ (4,652 ) $ 20,921 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 June 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. Six Months Ended June 30, 2016 and 2015 Successor Generation (a) ComEd PECO BGE PHI (b) Other (c) Intersegment Exelon Operating revenues (d) : 2016 Competitive businesses electric revenues $ 7,352 $ — $ — $ — $ — $ — $ (620 ) $ 6,732 Competitive businesses natural gas revenues 1,189 — — — — — — 1,189 Competitive businesses other revenues (212 ) — — — — — (1 ) (213 ) Rate-regulated electric revenues — 2,535 1,232 1,264 1,120 — (15 ) 6,136 Rate-regulated natural gas revenues — — 273 345 28 — (5 ) 641 Shared service and other revenues — — — — 23 803 (826 ) — 2015 Competitive businesses electric revenues $ 8,059 $ — $ — $ — $ — $ — $ (360 ) $ 7,699 Competitive businesses natural gas revenues 1,555 — — — — — — 1,555 Competitive businesses other revenues 460 — — — — — — 460 Rate-regulated electric revenues — 2,333 1,259 1,254 — — (2 ) 4,844 Rate-regulated natural gas revenues — — 387 410 — — (9 ) 788 Shared service and other revenues — — — — — 657 (658 ) (1 ) Intersegment revenues (e) : 2016 $ 621 $ 8 $ 4 $ 9 $ 23 $ 803 $ (1,466 ) $ 2 2015 360 2 1 8 — 656 (1,026 ) 1 Net income (loss): 2016 $ 285 $ 260 $ 224 $ 135 $ (257 ) $ (215 ) $ (2 ) $ 430 2015 875 189 209 157 — (55 ) (3 ) 1,372 _________ (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 six months ended June 30, 2016 include revenue from sales to PECO of $143 million and sales to BGE of $306 million in the Mid-Atlantic region, and sales to ComEd of $18 million in the Midwest region. For the six months ended June 30, 2015 , intersegment revenues for Generation include revenue from sales to PECO of $112 million and sales to BGE of $235 million in the Mid-Atlantic region, and sales to ComEd of $15 million in the Midwest region. For the Successor period of March 24, 2016 to June 30, 2016 , intersegment revenues for Generation include revenue from sales to Pepco of $94 million , sales to DPL of $47 million , and sales to ACE of $13 million in the Mid-Atlantic region. (b) Amounts included represent activity for the PHI's successor period, March 24, 2016 through June 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 six months ended June 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 June 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: Six Months Ended June 30, 2016 Six Months Ended June 30, 2015 Revenues (a) Intersegment Total Revenues (a)(c) Intersegment (c) Total (c) Mid-Atlantic $ 2,964 $ (28 ) $ 2,936 $ 2,920 $ (61 ) $ 2,859 Midwest 2,166 13 2,179 2,482 — 2,482 New England 823 (2 ) 821 1,232 (6 ) 1,226 New York 573 (24 ) 549 529 (1 ) 528 ERCOT 370 — 370 375 (3 ) 372 Other Power Regions 456 (9 ) 447 522 (19 ) 503 Total Revenues for Reportable Segments 7,352 (50 ) 7,302 8,060 (90 ) 7,970 Other (b) 977 50 1,027 2,014 90 2,104 Total Generation Consolidated Operating Revenues $ 8,329 $ — $ 8,329 $ 10,074 $ — $ 10,074 __________ (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. Also includes an $11 million and a $22 million increase to revenues for the amortization of intangible assets related to commodity contracts recorded at fair value for the six months ended June 30, 2016 and 2015 , respectively, unrealized mark-to-market losses of $553 million and gains of $179 million for the six months ended June 30, 2016 and 2015 , respectively, and elimination of intersegment revenues. (c) Exelon corrected an error in the June 30, 2015 balances within Intersegment Revenue and Revenue from external customers for an overstatement of $89 million of Intersegment Revenue for Reportable Segments for the six months ended June 30, 2015 , an understatement of Revenue from external customers for Reportable Segments of $89 million for the six months ended June 30, 2015 , an understatement of $89 million of Intersegment Revenue for Other for the six months ended June 30, 2015 , and an overstatement of Revenue from external customers for Other of $89 million for the six months ended June 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: Six Months Ended June 30, 2016 Six Months Ended June 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 $ 1,661 $ 8 $ 1,669 $ 1,690 $ (11 ) $ 1,679 Midwest 1,443 6 1,449 1,454 (6 ) 1,448 New England 204 (13 ) 191 277 (31 ) 246 New York 408 (13 ) 395 306 28 334 ERCOT 192 (54 ) 138 179 (54 ) 125 Other Power Regions 211 (37 ) 174 185 (77 ) 108 Total Revenues net of purchased power and fuel expense for Reportable Segments 4,119 (103 ) 4,016 4,091 (151 ) 3,940 Other (b) 190 103 293 701 151 852 Total Generation Revenues net of purchased power and fuel expense $ 4,309 $ — $ 4,309 $ 4,792 $ — $ 4,792 __________ (a) Includes purchases and sales from 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. Also includes a $7 million and a $24 million increase to RNF for the amortization of intangible assets related to commodity contracts for the six months ended June 30, 2016 and 2015 , respectively, unrealized mark-to-market losses of $201 million and gains of $397 million for the six months ended June 30, 2016 and 2015 , respectively, accelerated nuclear fuel amortization associated with nuclear decommissioning as discussed at Note 7 - Early Nuclear Plant Retirements of the Combined Notes to Consolidated Financial Statements of $9 million for the six months ended June 30, 2016 , and the elimination of intersegment revenue net of purchased power and fuel expense. (c) Exelon corrected an error in the June 30, 2015 balances within Intersegment RNF and RNF from external customers for an understatement of $25 million of Intersegment RNF for Reportable Segments for the six months ended June 30, 2015 , an overstatement of RNF from external customers for Reportable Segments of $10 million for the six months ended June 30, 2015 , an overstatement of $25 million of Intersegment RNF for Other for the six months ended June 30, 2015 , and an understatement of RNF from external customers for Other of $10 million for the six months ended June 30, 2015 . This also included an understatement of total RNF for Reportable Segments and an overstatement of total RNF for Other of $15 million for the six months ended June 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 June 30, 2016 - Successor Rate-regulated electric revenues $ 550 $ 279 $ 293 $ 3 $ (5 ) $ 1,120 Rate-regulated natural gas revenues — 29 — (1 ) — 28 Shared service and other revenues — — — 23 — 23 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 — — — — — — Six months ended June 30, 2015 - Predecessor - Predecessor Rate-regulated electric revenues $ 1,049 $ 580 $ 618 $ 115 $ — $ 2,362 Rate-regulated natural gas revenues — 111 — — — 111 Shared service and other revenues — — — — — — Intersegment revenues: March 24, 2016 to June 30, 2016 - Successor $ 2 $ 2 $ 1 $ 23 $ (5 ) $ 23 January 1, 2016 to March 23, 2016 - Predecessor 1 2 1 — (4 ) — Six months ended June 30, 2015 - Predecessor 2 3 2 — (7 ) — Net income (loss): March 24, 2016 to June 30, 2016 - Successor $ (92 ) $ (86 ) $ (102 ) $ — $ 23 $ (257 ) January 1, 2016 to March 23, 2016 - Predecessor 32 26 5 (44 ) — 19 Six months ended June 30, 2015 - Predecessor 68 40 15 (17 ) — 106 _________ (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 six months ended June 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	6 Months Ended
	Jun. 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. Based on the analysis completed, additional entities were 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 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. In May 2016, the FASB issued a final amendment regarding narrow scope improvements and practical expedients. The Registrants are currently assessing the impact of these updates. 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. 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 also does not apply to Available for Sale Debt Securities. 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. Based on the analysis completed, additional entities were 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 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. In May 2016, the FASB issued a final amendment regarding narrow scope improvements and practical expedients. The Registrants are currently assessing the impact of these updates. 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. 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 also does not apply to Available for Sale Debt Securities. 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. T
Fair Value Assets Measured On Recurring Basis Investments Valuation Techniques	t
Fair Value Assets Measured On Recurring Basis Cash And Cash Equivalents Valuation Techniques	Six Months Ended June 30, 2016 Six Months Ended June 30, 2015 Pepco Pepco DPL Life Insurance Contracts Life Insurance Contracts Life Insurance Contracts Balance as of December 31 $ 19 $ 18 $ 1 Total realized / unrealized gains (losses) Included in net income 2 3 — Purchases, sales, issuances and settlements Issuances (1 ) (1 ) — Settlements — — (1 ) Balance as of June 30 $ 20 $ 20 $ — The amount of total gains included in income attributed to the change in unrealized gains 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 six months ended June 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 June 30, 2016 $ (462 ) $ 34 $ 4 $ (462 ) $ 34 $ 5 Total gains (losses) included in net income for the six months ended June 30, 2016 (413 ) (21 ) 6 (413 ) (21 ) 7 Change in the unrealized gains (losses) relating to assets and liabilities held for the three months ended June 30, 2016 (274 ) 10 3 (274 ) 10 4 Change in the unrealized gains (losses) relating to assets and liabilities held for the six months ended June 30, 2016 (20 ) (25 ) 4 (20 ) (25 ) 5 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 June 30, 2015 $ (17 ) $ 10 $ 2 $ (17 ) $ 10 $ 2 Total gains (losses) included in net income for the six months ended June 30, 2015 (27 ) (12 ) 4 (27 ) (12 ) 4 Change in the unrealized gains (losses) relating to assets and liabilities held for the three months ended June 30, 2015 171 4 2 171 4 2 Change in the unrealized gains (losses) relating to assets and liabilities held for the six months ended June 30, 2015 340 15 3 340 15 3 Successor Predecessor PHI PHI Pepco Three Months Ended June 30, 2016 Three Months Ended June 30, 2015 Three Months Ended June 30, 2016 Three Months Ended June 30, 2015 Other, net Other, net Other, net Total gains (losses) included in net income $ 1 $ 2 $ 1 2 Change in the unrealized gains (losses) relating to assets and liabilities held 1 1 1 1 Successor Predecessor PHI PHI Pepco March 24, 2016 to June 30, 2016 January 1, 2016 to March 23, 2016 Six Months Ended June 30, 2015 Six Months Ended June 30, 2016 Six Months Ended June 30, 2015 Other, net Other, net Other, net Total gains (losses) included in net income $ 1 $ (17 ) $ 3 $ 2 $ 3 Change in the unrealized gains (losses) relating to assets and liabilities held 1 1 2 2 2 _________ (a) Other, net activity consists of realized and unrealized gains (losses) included in income for the NDT funds held by Generat Successor Predecessor PHI PHI Pepco Three Months Ended June 30, 2016 Three Months Ended June 30, 2015 Three Months Ended June 30, 2016 Three Months Ended June 30, 2015 Other, net Other, net Other, net Total gains (losses) included in net income $ 1 $ 2 $ 1 2 Change in the unrealized gains (losses) relating to assets and liabilities held 1 1 1 1
Fair Value Assets Measured On Recurring Basis Nuclear Decommissioning Trust Fund Investments Valuation Techniques	le. As of June 30, 2016 , Generation has outstanding commitments to invest in middle market lending, private equity investments and real estate investments of approximately $320 million , $37 million , and $479 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]	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 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)	6 Months Ended
	Jun. 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. Based on the analysis completed, additional entities were 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 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. In May 2016, the FASB issued a final amendment regarding narrow scope improvements and practical expedients. The Registrants are currently assessing the impact of these updates. 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. 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 also does not apply to Available for Sale Debt Securities. 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. Based on the analysis completed, additional entities were 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 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. In May 2016, the FASB issued a final amendment regarding narrow scope improvements and practical expedients. The Registrants are currently assessing the impact of these updates. 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. 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 also does not apply to Available for Sale Debt Securities. 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. T

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	6 Months Ended
	Jun. 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 June 30, 2016 and December 31, 2015 are as follows: June 30, 2016 December 31, 2015 Successor Predecessor Exelon (a)(b) Generation BGE PHI (b) ACE Exelon (a) Generation BGE PHI ACE Current assets $ 818 $ 784 $ 17 $ 14 $ 10 $ 909 $ 881 $ 23 $ 12 $ 12 Noncurrent assets 8,083 8,048 3 31 19 8,009 8,004 3 18 18 Total assets $ 8,901 $ 8,832 $ 20 $ 45 $ 29 $ 8,918 $ 8,885 $ 26 $ 30 $ 30 Current liabilities $ 597 $ 464 $ 82 48 $ 44 $ 473 $ 387 $ 81 $ 48 $ 48 Noncurrent liabilities 3,070 2,951 — 118 106 2,927 2,884 41 124 124 Total liabilities $ 3,667 $ 3,415 $ 82 $ 166 $ 150 $ 3,400 $ 3,271 $ 122 $ 172 $ 172 _______ (a) Includes certain purchase accounting adjustments not pushed down to the BGE standalone entity. June 30, 2016 Commercial Agreement VIEs Equity Investment VIEs Total Total assets (a) $ 503 $ 395 $ 898 Total liabilities (a) 106 281 387 Exelon's ownership interest in VIE (a) — 80 80 Other ownership interests in VIE (a) 397 34 431 Registrants’ maximum exposure to loss: Carrying amount of equity method investments — 137 137 Contract intangible asset 9 — 9 Debt and payment guarantees — 3 3 Net assets pledged for Zion Station decommissioning (b) 13 — 13 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 $161 million and $206 million as of June 30, 2016 and December 31, 2015 , respectively; offset by payables to ZionSolutions LLC of $148 million and $189 million as of June 30, 2016 and December 31, 2015 , respectively. These items are included to provide information regarding the relative size of the ZionSolutions LLC unconsolidated VI June 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 $ 138 $ 138 $ — $ — $ — $ 164 $ 164 $ — $ — $ — Restricted cash 53 26 17 10 10 100 77 23 12 12 Accounts receivable, net Customer 253 253 — — — 219 219 — — — Other 44 44 — — — 43 43 — — — Mark-to-market derivatives assets 41 41 — — — 140 140 — — — Inventory Materials and supplies 189 189 — — — 181 181 — — — Other current assets 37 30 — 4 — 35 30 — — — Total current assets 755 721 17 14 10 882 854 23 12 12 Property, plant and equipment, net 5,147 5,147 — — — 5,160 5,160 — — — Nuclear decommissioning trust funds 2,100 2,100 — — — 2,036 2,036 — — — Goodwill 47 47 — — — 47 47 — — — Mark-to-market derivatives assets 24 24 — — — 53 53 — — — Other noncurrent assets 167 133 3 31 19 90 85 3 18 18 Total noncurrent assets 7,485 7,451 3 31 19 7,386 7,381 3 18 18 Total assets $ 8,240 $ 8,172 $ 20 $ 45 $ 29 $ 8,268 $ 8,235 $ 26 $ 30 $ 30 Long-term debt due within one year $ 312 $ 183 $ 81 $ 46 $ 42 $ 111 $ 27 $ 79 $ 46 $ 46 Accounts payable 146 146 — — — 216 216 — — — Accrued expenses 79 76 1 2 2 115 113 2 2 2 Mark-to-market derivative liabilities 21 21 — — — 5 5 — — — Unamortized energy contract liabilities 13 13 — — — 12 12 — — — Other current liabilities 23 23 — — — 13 13 — — — Total current liabilities 594 462 82 48 44 472 386 81 48 48 Long-term debt 675 557 — 118 106 666 623 41 124 124 Asset retirement obligations 2,053 2,053 — — — 1,999 1,999 — — — Pension obligation (c) 9 9 — — — 9 9 — — — Unamortized energy contract liabilities 31 31 — — — 39 39 — — — Other noncurrent liabilities 99 99 — — — 79 79 — — — Total noncurrent liabilities 2,867 2,749 — 118 106 2,792 2,749 41 124 124 Total liabilities $ 3,461 $ 3,211 $ 82 $ 166 $ 150 $ 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)	6 Months Ended
	Jun. 30, 2016
Business Combinations [Abstract]
Finite-Lived and Indefinite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block]	PHI Exelon (a) Beginning balance $ — $ 2,672 Goodwill from business combination 4,016 4,016 Measurement period adjustment 8 8 Ending balance $ 4,024 $ 6,696 _____________ (a) As of June 30, 2016 , there were no changes to the carrying amount of goodwill for ComEd and Generation, see Note 11 — Intangible Assets of the Exelon 2015 Form 10-K for further information.
Business Acquisition, Pro Forma Information, Nonrecurring Adjustments [Table Text Block]	Three Months Ended Six Months Ended Year Ended December 31, 2016 (a) 2015 (b) 2016 (a) 2015 (b) 2015 (c) Total operating revenues $ 6,910 $ 7,522 $ 15,466 $ 17,584 $ 33,823 Net income attributable to common shareholders 268 623 845 1,423 2,618 Basic earnings per share $ 0.29 $ 0.68 $ 0.92 $ 1.55 $ 2.85 Diluted earnings per share 0.29 0.67 0.91 1.54 2.84 ______________ (a) The amounts above include adjustments for non-recurring costs directly related to the merger of $1 million and $641 million for the three and six months ended June 30, 2016 , respectively, and intercompany revenue of $170 million for the six months ended June 30, 2016 . (b) The amounts above include adjustments for non-recurring costs directly related to the merger of $(82) million and $35 million and intercompany revenue of $111 million and $233 million for the three and six months ended June 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 DPL ACE PHI Exelon Customer bill credit 2016 - 2017 $ 65 $ 58 $ 62 $ 185 $ 185 Energy efficiency 2016 - 2021 — — — — 64 Charitable contributions 2016 - 2026 28 12 10 50 50 Customer base rate credit 2016 - 2019 26 — — 26 26 Delivery system modernization Q2 2016 — — — — 22 Green sustainability fund Q2 2016 — — — — 14 Workforce development 2016 - 2020 — — — — 11 Most favored nation 19 32 48 99 129 Other 1 2 — 3 7 Total $ 139 $ 104 $ 120 $ 363 $ 508 (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 11,076 Regulatory assets 5,015 Other assets 248 Goodwill 4,024 Total assets $ 21,804 Current liabilities $ 2,763 Unamortized energy contracts 1,515 Regulatory liabilities 297 Long-term debt, including current maturities 5,636 Deferred income taxes 3,443 Pension and OPEB liability 821 Other liabilities 187 Total liabilities $ 14,662 Total purchase price $ 7,142
Restructuring and Related Costs	Three Months Ended June 30, Six Months Ended June 30, Acquisition, Integration and Financing Costs (a) 2016 2015 2016 2015 Exelon (b) $ 1 $ (87 ) $ 103 $ 21 Generation 4 7 20 15 ComEd (c) 1 3 (7 ) 6 PECO 1 1 2 2 BGE (d) (5 ) 1 (4 ) 3 Pepco (d) (4 ) 1 23 2 DPL (d) — 1 16 1 ACE 2 1 15 1 Successor Predecessor Successor Predecessor Acquisition, Integration and Financing Costs (a) Three Months Ended Three Months Ended March 24, 2016 to June 30, 2016 January 1, 2016 to March 23, 2016 Six Months Ended June 30, 2015 PHI (d) $ (1 ) $ 5 $ 55 $ 29 $ 14 ______________ (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 six months ended June 30, 2016 , includes the reversal of previously incurred acquisition, integration and financing costs of $8 million incurred at ComEd that has been deferred and recorded as a regulatory asset Successor Exelon Generation ComEd PECO BGE PHI Pepco (b) DPL (c) ACE Three Months Ended June 30, 2016 Severance benefits (a) $ 2 $ (1 ) $ (1 ) $ — $ — $ 4 $ 2 $ 1 $ 1 Six Months Ended June 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 $(1) million , $(1) million , less than $1 million , less than $1 million , $2 million , $1 million and $1 million , respectively, for amounts billed by BSC and/or PHISCO through intercompany allocations for the three months ended June 30, 2016 , and $8 million , $2 million , $1 million , $1 million , $19 million , $11 million and $10 million for the six months ended June 30, 2016 . Exelon Generation (a) ComEd Three Months Ended June 30, 2016 $ 2 $ 1 $ 1 June 30, 2015 1 1 — Six Months Ended June 30, 2016 $ 4 $ 3 $ 1 June 30, 2015 21 21 —

Regulatory Matters (Tables)

Regulatory Matters (Tables)	6 Months Ended
	Jun. 30, 2016
Regulated Operations [Abstract]
Schedule of Regulatory Assets	Successor June 30, 2016 Exelon ComEd PECO BGE PHI Pepco DPL ACE Regulatory liabilities Other postretirement benefits $ 90 $ — $ — $ — $ — $ — $ — $ — Nuclear decommissioning 2,642 2,205 437 — — — — — Removal costs 1,648 1,330 — 172 146 20 126 — Deferred rent (s) 42 — — — 42 — — — Energy efficiency and demand response programs 134 97 37 — — — — — DLC program costs 9 — 9 — — — — — Electric distribution tax repairs 84 — 84 — — — — — Gas distribution tax repairs 24 — 24 — — — — — Energy and transmission programs (h)(i)(s)(j)(k)(l) 164 41 63 8 52 22 21 9 Over-recovered revenue decoupling (o) 3 — — 3 — — — — Other 52 4 3 14 32 9 8 14 Total regulatory liabilities 4,892 3,677 657 197 272 51 155 23 Less: current portion 503 153 128 60 101 27 53 21 Total non-current regulatory liabilities $ 4,389 $ 3,524 $ 529 $ 137 $ 171 $ 24 $ 102 $ 2 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 1,616 64 1,473 79 214 137 36 41 AMI programs (c) 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)(s)(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 (m) 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)(s)(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 June 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 June 30, 2016 , includes transmission-related regulatory assets that require FERC approval separate from the transmission formula rate of $ 19 million , $30 million , $38 million , $19 million and $17 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 June 30, 2016 , the portion of deferred AMI program costs pending approval from the MDPSC is $32 million for BGE, $139 million for Pepco and $43 million for DPL, of which $78 million for Pepco and $14 million for DPL relates to retired legacy meters which are not earning a return and $2 million of post-test year costs for Pepco which are not earning a return. (d) As of June 30, 2016 , ComEd’s regulatory asset of $207 million was comprised of $163 million for the 2014 - 2016 annual reconciliations and $44 million related to significant one-time events including $28 million of deferred storm costs, $11 million of Constellation and PHI merger and integration related costs and $5 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 June 30, 2016 , ComEd’s regulatory asset of $41 million included $4 million related to under-recovered energy costs, $30 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 June 30, 2016 , ComEd’s regulatory liability of $41 million included $13 million related to over-recovered energy costs and $28 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 June 30, 2016 , BGE's regulatory asset of $36 million included $6 million of costs associated with transmission costs recoverable through its FERC approved formula rate, $29 million related to under-recovered electric energy costs, and $1 million of abandonment costs to be recovered upon FERC approval. As of June 30, 2016 , BGE's regulatory liability of $8 million related to $8 million of over-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 June 30, 2016 , Pepco's regulatory liability of $22 million included $12 million of over-recovered transmission costs and $10 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 June 30, 2016 , DPL's regulatory asset of $6 million related to under-recovered electric energy costs. As of June 30, 2016 , DPL's regulatory liability of $21 million included $4 million related to over-recovered natural gas costs under the GCR mechanism, $10 million of over-recovered electric energy costs, and $7 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 June 30, 2016 , ACE's regulatory asset of $20 million related to of under-recovered electric energy costs. As of June 30, 2016 , ACE's regulatory liability of $9 million related to over-recovered transmission 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 June 30, 2016 , BGE's regulatory asset of $11 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 June 30, 2016 , BGE had a regulatory asset of $26 million related to under-recovered electric revenue decoupling and a regulatory liability of $3 million related to over-recovered natural gas 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 asset recorded at Exelon and PHI for the difference between the carrying value and fair value of alternative energy credits at Pepco, DPL and ACE recorded at Exelon and PHI that are recoverable through the rate making process. (r) 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. (s) As of June 30, 2016 , PECO's regulatory liability of $63 million included $31 million related to over-recovered costs under the DSP program, $23 million related to the over-recovered natural gas costs under the PGC, $7 million related to over-recovered non-bypassable transmission service charges and $2 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 June 30, 2016 Exelon ComEd PECO BGE PHI Pepco DPL ACE Regulatory liabilities Other postretirement benefits $ 90 $ — $ — $ — $ — $ — $ — $ — Nuclear decommissioning 2,642 2,205 437 — — — — — Removal costs 1,648 1,330 — 172 146 20 126 — Deferred rent (s) 42 — — — 42 — — — Energy efficiency and demand response programs 134 97 37 — — — — — DLC program costs 9 — 9 — — — — — Electric distribution tax repairs 84 — 84 — — — — — Gas distribution tax repairs 24 — 24 — — — — — Energy and transmission programs (h)(i)(s)(j)(k)(l) 164 41 63 8 52 22 21 9 Over-recovered revenue decoupling (o) 3 — — 3 — — — — Other 52 4 3 14 32 9 8 14 Total regulatory liabilities 4,892 3,677 657 197 272 51 155 23 Less: current portion 503 153 128 60 101 27 53 21 Total non-current regulatory liabilities $ 4,389 $ 3,524 $ 529 $ 137 $ 171 $ 24 $ 102 $ 2 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 1,616 64 1,473 79 214 137 36 41 AMI programs (c) 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)(s)(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 (m) 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)(s)(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 June 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 June 30, 2016 , includes transmission-related regulatory assets that require FERC approval separate from the transmission formula rate of $ 19 million , $30 million , $38 million , $19 million and $17 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 June 30, 2016 , the portion of deferred AMI program costs pending approval from the MDPSC is $32 million for BGE, $139 million for Pepco and $43 million for DPL, of which $78 million for Pepco and $14 million for DPL relates to retired legacy meters which are not earning a return and $2 million of post-test year costs for Pepco which are not earning a return. (d) As of June 30, 2016 , ComEd’s regulatory asset of $207 million was comprised of $163 million for the 2014 - 2016 annual reconciliations and $44 million related to significant one-time events including $28 million of deferred storm costs, $11 million of Constellation and PHI merger and integration related costs and $5 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 June 30, 2016 , ComEd’s regulatory asset of $41 million included $4 million related to under-recovered energy costs, $30 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 June 30, 2016 , ComEd’s regulatory liability of $41 million included $13 million related to over-recovered energy costs and $28 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 June 30, 2016 , BGE's regulatory asset of $36 million included $6 million of costs associated with transmission costs recoverable through its FERC approved formula rate, $29 million related to under-recovered electric energy costs, and $1 million of abandonment costs to be recovered upon FERC approval. As of June 30, 2016 , BGE's regulatory liability of $8 million related to $8 million of over-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 June 30, 2016 , Pepco's regulatory liability of $22 million included $12 million of over-recovered transmission costs and $10 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 June 30, 2016 , DPL's regulatory asset of $6 million related to under-recovered electric energy costs. As of June 30, 2016 , DPL's regulatory liability of $21 million included $4 million related to over-recovered natural gas costs under the GCR mechanism, $10 million of over-recovered electric energy costs, and $7 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 June 30, 2016 , ACE's regulatory asset of $20 million related to of under-recovered electric energy costs. As of June 30, 2016 , ACE's regulatory liability of $9 million related to over-recovered transmission 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 June 30, 2016 , BGE's regulatory asset of $11 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 June 30, 2016 , BGE had a regulatory asset of $26 million related to under-recovered electric revenue decoupling and a regulatory liability of $3 million related to over-recovered natural gas 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 asset recorded at Exelon and PHI for the difference between the carrying value and fair value of alternative energy credits at Pepco, DPL and ACE recorded at Exelon and PHI that are recoverable through the rate making process. (r) 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. (s) As of June 30, 2016 , PECO's regulatory liability of $63 million included $31 million related to over-recovered costs under the DSP program, $23 million related to the over-recovered natural gas costs under the PGC, $7 million related to over-recovered non-bypassable transmission service charges and $2 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]	For each of the following years, the 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 (b) $ 90 $ 12 $ 2 $ 8 $ 8 Annual reconciliation (decrease) increase 4 3 (10 ) (10 ) (14 ) MAPP abandonment recovery decrease — — (15 ) (12 ) — Total revenue requirement increase (decrease) $ 94 $ 15 $ (23 ) $ (14 ) $ (6 ) Allowed return on rate base (c) 8.47 % 8.09 % 7.88 % 7.21 % 7.83 % Previously authorized allowed return on rate base (c) 8.61 % 8.46 % 8.36 % 7.80 % 8.51 % Allowed ROE (d) 11.50 % 10.50 % 10.5 % 10.50 % 10.50 % _____________ (a) All rates are effective June 2016. (b) For BGE, this excludes the increase in revenue requirement associated with dedicated facilities charges of $13 million . (c) Refers to the weighted average debt and equity return on transmission rate bases. (d) 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)	6 Months Ended
	Jun. 30, 2016
Property, Plant and Equipment [Abstract]
ImplicationsofPotentialEarlyPlantRetirement [Table Text Block]	(in millions) TMI Ginna NMP Asset Balances Materials and supplies inventory $ 38 $ 30 $ 69 Nuclear fuel inventory, net 104 47 235 Completed plant, net 968 125 1,137 Construction work in progress 35 12 70 Liability Balances Asset retirement obligation (485 ) (659 ) (770 ) NRC License Renewal Term 2034 2029 2029 (unit 1) 2046 (unit 2)
Incremental Expense Plant Retirement [Table Text Block]

Fair Value of Financial Asset33

Fair Value of Financial Assets and Liabilities (Tables)	6 Months Ended
	Jun. 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 June 30, 2016 and December 31, 2015 : Exelon June 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 954 $ 3 $ 951 $ — $ 954 Long-term debt (including amounts due within one year) (a) 34,234 1,135 33,863 2,176 37,174 Long-term debt to financing trusts (b) 641 — — 689 689 SNF obligation 1,023 — 835 — 835 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
Assets and liabilities measured and recorded at fair value on recurring basis	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 June 30, 2016 and December 31, 2015 : Generation Exelon As of June 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) $ 42 $ — $ — $ — $ 42 $ 1,311 $ — $ — $ — $ 1,311 NDT fund investments Cash equivalents (b) 381 12 — — 393 381 12 — — 393 Equities 3,205 215 1 1,908 5,329 3,205 215 1 1,908 5,329 Fixed income Corporate debt — 1,910 249 — 2,159 — 1,910 249 — 2,159 U.S. Treasury and agencies 1,452 29 — — 1,481 1,452 29 — — 1,481 Foreign governments — 44 — — 44 — 44 — — 44 State and municipal debt — 285 — — 285 — 285 — — 285 Other (c) — 60 — 399 459 — 60 — 399 459 Fixed income subtotal 1,452 2,328 249 399 4,428 1,452 2,328 249 399 4,428 Middle market lending — — 465 — 465 — — 465 — 465 Private equity — — — 124 124 — — — 124 124 Real estate — — — 46 46 — — — 46 46 NDT fund investments subtotal (d) 5,038 2,555 715 2,477 10,785 5,038 2,555 715 2,477 10,785 Pledged assets for Zion Station decommissioning Cash equivalents 15 — — — 15 15 — — — 15 Equities — 6 — — 6 — 6 — — 6 Fixed income U.S. Treasury and agencies 23 2 — — 25 23 2 — — 25 Corporate debt — 9 — — 9 — 9 — — 9 Generation Exelon As of June 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 23 11 — — 34 23 11 — — 34 Middle market lending — — 25 81 106 — — 25 81 106 Pledged assets for Zion Station (e) 38 17 25 81 161 38 17 25 81 161 Rabbi trust investments Cash equivalents 8 — — — 8 81 — — — 81 Mutual funds 18 — — — 18 49 — — — 49 Fixed income — — — — — — 14 — — 14 Life insurance contracts — 17 — — 17 — 63 20 — 83 Rabbi trust investments subtotal 26 17 — — 43 130 77 20 — 227 Commodity derivative assets Economic hedges 1,342 3,087 1,506 — 5,935 1,343 3,087 1,506 — 5,936 Proprietary trading 25 71 31 — 127 25 71 31 — 127 Effect of netting and allocation of collateral (f) (1,308 ) (2,733 ) (779 ) — (4,820 ) (1,309 ) (2,733 ) (779 ) — (4,821 ) Commodity derivative assets subtotal 59 425 758 — 1,242 59 425 758 — 1,242 Interest rate and foreign currency derivative assets Derivatives designated as hedging instruments — — — — — — 47 — — 47 Economic hedges — 28 — — 28 — 28 — — 28 Proprietary trading 10 1 — — 11 10 1 — — 11 Effect of netting and allocation of collateral (7 ) (16 ) — — (23 ) (7 ) (16 ) — — (23 ) Interest rate and foreign currency derivative assets subtotal 3 13 — — 16 3 60 — — 63 Other investments — — 37 — 37 — — 37 — 37 Total assets 5,206 3,027 1,535 2,558 12,326 6,579 3,134 1,555 2,558 13,826 Liabilities Commodity derivative liabilities Economic hedges (1,456 ) (3,089 ) (1,013 ) — (5,558 ) (1,456 ) (3,089 ) (1,234 ) — (5,779 ) Proprietary trading (24 ) (73 ) (34 ) — (131 ) (24 ) (73 ) (34 ) — (131 ) Effect of netting and allocation of collateral (f) 1,431 3,012 898 — 5,341 1,431 3,012 898 — 5,341 Commodity derivative liabilities subtotal (49 ) (150 ) (149 ) — (348 ) (49 ) (150 ) (370 ) — (569 ) Interest rate and foreign currency derivative liabilities Derivatives designated as hedging instruments — (21 ) — — (21 ) — (23 ) — — (23 ) Economic hedges — (19 ) — — (19 ) — (19 ) — — (19 ) Proprietary trading (9 ) — — — (9 ) (9 ) — — — (9 ) Effect of netting and allocation of collateral 10 16 — — 26 10 16 — — 26 Interest rate and foreign currency derivative liabilities subtotal 1 (24 ) — — (23 ) 1 (26 ) — — (25 ) Deferred compensation obligation — (30 ) — — (30 ) — (127 ) — — (127 ) Total liabilities (48 ) (204 ) (149 ) — (401 ) (48 ) (303 ) (370 ) — (721 ) Total net assets $ 5,158 $ 2,823 $ 1,386 $ 2,558 $ 11,925 $ 6,531 $ 2,831 $ 1,185 $ 2,558 $ 13,105 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 $332 million million and $329 million at June 30, 2016 and December 31, 2015 and restricted cash of $97 million and $121 million at June 30, 2016 and December 31, 2015 . Exelon excludes cash of $423 million and $763 million at June 30, 2016 and December 31, 2015 and restricted cash of $136 million and $178 million at June 30, 2016 and December 31, 2015 and includes long term restricted cash of $22 million at June 30, 2016 , which is reported in other deferred debits on the balance sheet. (b) Includes $71 million and $52 million of cash received from outstanding repurchase agreements at June 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 $(16) million and $(8) million , which have a total notional amount of $1,303 million and $1,236 million at June 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 $(48) million and $(3) million at June 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 June 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 $123 million , $279 million and $119 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of June 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 June 30, 2016 and December 31, 2015 : ComEd PECO BGE As of June 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) $ 700 $ — $ — $ 700 $ 184 $ — $ — $ 184 $ 20 $ — $ — $ 20 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 700 — — 700 191 11 — 202 24 — — 24 Liabilities Deferred compensation obligation — (8 ) — (8 ) — (10 ) — (10 ) — (4 ) — (4 ) Mark-to-market derivative liabilities (b) — — (221 ) (221 ) — — — — — — — — Total liabilities — (8 ) (221 ) (229 ) — (10 ) — (10 ) — (4 ) — (4 ) Total net assets (liabilities) $ 700 $ (8 ) $ (221 ) $ 471 $ 191 $ 1 $ — $ 192 $ 24 $ (4 ) $ — $ 20 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 $ 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 $36 million and $38 million at June 30, 2016 and December 31, 2015 and restricted cash of $2 million and $2 million at June 30, 2016 and December 31, 2015 . PECO excludes cash of $22 million and $27 million at June 30, 2016 and December 31, 2015 . BGE excludes cash of $5 million and $6 million at June 30, 2016 and December 31, 2015 and restricted cash of $2 million and $2 million at June 30, 2016 and December 31, 2015 and includes long term restricted cash of $3 million at June 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 $18 million and $203 million , respectively, at June 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 June 30, 2016 and December 31, 2015 : Successor Predecessor As of June 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) $ 344 $ — $ — $ 344 $ 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 20 42 — 27 19 46 Rabbi trust investments subtotal 73 36 20 129 12 42 19 73 Total assets 417 36 20 473 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 $ 417 $ 8 $ 20 $ 445 $ 54 $ 12 $ 37 $ 103 Pepco DPL ACE As of June 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) $ 155 $ — $ — $ 155 $ 12 $ — $ — $ 12 $ 176 $ — $ — $ 176 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 20 42 — — — — — — — — Rabbi trust investments subtotal 43 36 20 99 — — — — — — — — Total assets 198 36 20 254 12 — — 12 176 — — 176 Liabilities Deferred compensation obligation — (5 ) — (5 ) — (1 ) — (1 ) — — — — Total liabilities — (5 ) — (5 ) — (1 ) — (1 ) — — — — Total net assets (liabilities) $ 198 $ 31 $ 20 $ 249 $ 12 $ (1 ) $ — $ 11 $ 176 $ — $ — $ 176 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 $13 million and $16 million at June 30, 2016 and December 31, 2015 and includes long term restricted cash of $19 million and $18 million at June 30, 2016 and December 31, 2015 which is reported in other deferred debits on the balance sheet. Pepco excludes cash of $5 million and $5 million at June 30, 2016 and December 31, 2015 . DPL excludes cash of $4 million and $5 million at June 30, 2016 and December 31, 2015 . ACE excludes cash of $4 million and $3 million at June 30, 2016 and December 31, 2015 and includes long term restricted cash of $19 million and $18 million at June 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
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 six months ended June 30, 2016 and 2015 : Successor Generation ComEd PHI Exelon Three Months Ended June 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 March 31, 2016 $ 684 $ 25 $ 1,047 $ 36 $ 1,792 $ (265 ) $ 20 $ — $ 1,547 Total realized / unrealized gains (losses) Included in net income 4 — (428 ) (b) — (424 ) — 1 — (423 ) Included in noncurrent payables to affiliates 8 — — — 8 — — (8 ) — Included in payable for Zion Station decommissioning — — — — — — — — — Included in regulatory assets — — — — — 44 — 8 52 Change in collateral — — (32 ) — (32 ) — — — (32 ) Purchases, sales, issuances and settlements Purchases 85 — 23 1 109 — — — 109 Sales (1 ) — (1 ) — (2 ) — — — (2 ) Issuances — — — — — — (1 ) — (1 ) Settlements (65 ) — — — (65 ) — — — (65 ) Transfers into Level 3 — — — — — — — — — Transfers out of Level 3 — — — — — — — — Balance at June 30, 2016 $ 715 $ 25 $ 609 $ 37 $ 1,386 $ (221 ) $ 20 $ — $ 1,185 The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of June 30, 2016 $ 3 $ — $ (264 ) $ — $ (261 ) $ 1 $ — $ (260 ) Successor Generation ComEd PHI (c) Exelon Six Months Ended June 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 6 — (434 ) (b) — (428 ) — 1 — (427 ) Included in noncurrent payables to affiliates 12 — — — 12 — — (12 ) — Included in payable for Zion Station decommissioning — 2 — — 2 — — — 2 Included in regulatory assets/liabilities — — — — — 26 — 12 38 Change in collateral — — (82 ) — (82 ) — — — (82 ) Purchases, sales, issuances and settlements Purchases 119 1 82 4 206 — — — 206 Sales (1 ) — (3 ) — (4 ) — — — (4 ) Issuances — — — — — — (1 ) — (1 ) Settlements (91 ) — — — (91 ) — — — (91 ) Transfers into Level 3 — — 2 — 2 — — — 2 Transfers out of Level 3 — — (7 ) — (7 ) — — — (7 ) Balance as of June 30, 2016 $ 715 $ 25 $ 609 $ 37 $ 1,386 $ (221 ) $ 20 $ — $ 1,185 The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of June 30, 2016 $ 4 $ — $ (45 ) $ — $ (41 ) $ — $ 1 $ — $ (40 ) ___________________ (a) Includes $40 million of increases in fair value and realized losses due to settlements of $4 million recorded in purchased power expense associated with floating-to-fixed energy swap contracts with unaffiliated suppliers for the three months ended June 30, 2016 . Includes $ 15 million of increases in fair value and realized losses due to settlements of $ 11 million for the six months ended June 30, 2016 . (b) Includes a reduction for the reclassification of $164 million and $389 million of realized gains due to the settlement of derivative contracts recorded in results of operations for the three and six months ended June 30, 2016 , respectively. (c) Successor period represents activity from March 24, 2016 through June 30, 2016 . See tables below for PHI's predecessor periods, as well as activity for Pepco and DPL for the three and six months ended June 30, 2016 . Generation ComEd Exelon Three Months Ended June 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 March 31, 2015 $ 612 $ 44 $ 1,066 $ 3 $ 1,725 $ (241 ) $ — $ 1,484 Total realized / unrealized gains (losses) — Included in net income 2 — (7 ) (b) — (5 ) — — (5 ) Included in noncurrent payables to affiliates 7 — — — 7 — (7 ) — Included in payable for Zion Station decommissioning — (2 ) — — (2 ) — — (2 ) Included in regulatory assets — — — — — 18 7 25 Change in collateral — — (30 ) — (30 ) — — (30 ) Purchases, sales, issuances and settlements Purchases 79 1 16 27 123 — — 123 Sales — (2 ) (5 ) — (7 ) — — (7 ) Settlements (33 ) — — — (33 ) — — (33 ) Transfers into Level 3 — — 11 — 11 — — 11 Transfers out of Level 3 — — (30 ) — (30 ) — — (30 ) Balance as of June 30, 2015 $ 667 $ 41 $ 1,021 $ 30 $ 1,759 $ (223 ) $ — $ 1,536 The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of June 30, 2015 $ 2 $ — $ 175 $ — $ 177 $ — $ — $ 177 Generation ComEd Exelon Six Months Ended June 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 — (39 ) (b) — (35 ) — — (35 ) Included in noncurrent payables to affiliates 17 — — — 17 — (17 ) — Included in payable for Zion Station decommissioning — 1 — — 1 — — 1 Included in regulatory assets — — — — — (16 ) 17 1 Change in collateral — — (18 ) — (18 ) — — (18 ) Purchases, sales, issuances and settlements Purchases 107 1 57 27 192 — — 192 Sales (8 ) (11 ) (5 ) — (24 ) — — (24 ) Settlements (62 ) — — — (62 ) — — (62 ) Transfers into Level 3 4 — 11 — 15 — — 15 Transfers out of Level 3 — — (35 ) — (35 ) — — (35 ) Balance as of June 30, 2015 $ 667 $ 41 $ 1,021 $ 30 $ 1,759 $ (223 ) $ — $ 1,536 The amount of total gains (losses) included in income attributed to the change in unrealized gains (losses) related to assets and liabilities as of June 30, 2015 $ 3 $ — $ 355 $ — $ 358 $ — $ — $ 358 _________ (a) Includes $14 million of increases in fair value and realized losses due to settlements of $4 million recorded in purchased power expense associated with floating-to-fixed energy swap contracts with unaffiliated suppliers for the three months ended June 30, 2015. Includes $22 million of decreases in fair value and realized losses due to settlements of $6 million for the six months ended June 30, 2015 . (b) Includes an increase for the reclassification of $182 million and $394 million of realized losses due to the settlement of derivative contracts recorded in results of operations for the three and six months ended June 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 June 30, 2016 Valuation Technique Unobservable Input Range Mark-to-market derivatives — Economic Hedges (Exelon and Generation) (a)(c) $ 493 Discounted Forward power $8 - $130 Forward gas $1.74 - $10.19 Option Model Volatility 5% - 353% Mark-to-market derivatives — Proprietary trading (Exelon and Generation) (a)(c) $ (3 ) Discounted Forward power $12 - $84 Mark-to-market derivatives (Exelon and ComEd) $ (221 ) Discounted Forward heat (b) 8x - 9x Marketability 3% - 8% Renewable 88% - 120% _________ (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 $119 million as of June 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 June 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 208 $ — $ 208 $ — $ 208 Long-term debt (including amounts due within one year) (a) 9,066 — 7,953 1,577 9,530 SNF obligation 1,023 — 835 — 835 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 June 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 35 $ — $ 35 $ — $ 35 Long-term debt (including amounts due within one year) (a) 7,695 — 8,832 — 8,832 Long-term debt to financing trusts (b) 205 — — 209 209 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 June 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 2,581 $ — $ 3,002 $ — $ 3,002 Long-term debt to financing trusts 184 — — 205 205 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 June 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Short-term liabilities $ 211 $ 3 $ 208 $ — $ 211 Long-term debt (including amounts due within one year) (a) 1,820 — 2,136 — 2,136 Long-term debt to financing trusts (b) 252 — — 275 275 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 June 30, 2016 Carrying Amount Fair Value Successor Level 1 Level 2 Level 3 Total Short-term liabilities $ 500 $ — $ 500 $ — $ 500 Long-term debt (including amounts due within one year) 6,073 — 5,752 599 6,351 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 June 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 2,349 $ — $ 3,028 $ 2 $ 3,030 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 June 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 1,265 $ — $ 1,279 $ 102 $ 1,381 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 June 30, 2016 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total Long-term debt (including amounts due within one year) (a) $ 1,180 $ — $ 1,083 $ 301 $ 1,384 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)	6 Months Ended
	Jun. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of the derivative fair value	The following table provides a summary of the derivative fair value balances recorded by the Registrants as of June 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) $ 4,089 $ 99 $ (3,438 ) $ 750 $ — $ 1 $ (1 ) $ — $ — $ 750 Mark-to-market derivative assets (noncurrent assets) 1,846 28 (1,382 ) 492 — — — — — 492 Total mark-to-market derivative assets 5,935 127 (4,820 ) 1,242 — 1 (1 ) — — 1,242 Mark-to-market derivative liabilities (current liabilities) (3,797 ) (94 ) 3,766 (125 ) (18 ) — — — — (143 ) Mark-to-market derivative liabilities (noncurrent liabilities) (1,761 ) (37 ) 1,575 (223 ) (203 ) — — — — (426 ) Total mark-to-market derivative liabilities (5,558 ) (131 ) 5,341 (348 ) (221 ) — — — — (569 ) Total mark-to-market derivative net assets (liabilities) $ 377 $ (4 ) $ 521 $ 894 $ (221 ) $ 1 $ (1 ) $ — $ — $ 673 ______ (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 $159 million and $88 million , respectively, and current and noncurrent liabilities are shown net of collateral of $170 million and $104 million , respectively. The total cash collateral posted, net of cash collateral received and offset against mark-to-market assets and liabilities was $521 million at June 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. June 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) $ — $ 14 $ 6 $ (11 ) $ 9 $ — $ 9 Mark-to-market derivative assets (noncurrent assets) — 14 5 (12 ) 7 47 54 Total mark-to-market derivative assets — 28 11 (23 ) 16 47 63 Mark-to-market derivative liabilities (current liabilities) (8 ) (9 ) (4 ) 12 (9 ) — (9 ) Mark-to-market derivative liabilities (noncurrent liabilities) (13 ) (10 ) (5 ) 14 (14 ) (2 ) (16 ) Total mark-to-market derivative liabilities (21 ) (19 ) (9 ) 26 (23 ) (2 ) (25 ) Total mark-to-market derivative net assets (liabilities) $ (21 ) $ 9 $ 2 $ 3 $ (7 ) $ 45 $ 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. 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 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 June 30, Income Statement Location 2016 2015 2016 2015 Gain (loss) on Swaps Gain (loss) on Borrowings Exelon Interest expense $ 5 $ (11 ) $ (1 ) $ 16 Six Months Ended June 30, Income Statement Location 2016 2015 2016 2015 Gain (loss) on Swaps Gain (loss) on Borrowings Generation Interest expense (a) $ — $ (1 ) $ — $ — Exelon Interest expense 22 (1 ) (16 ) 9 __________ (a) For the six months ended June 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 June 30, 2016 Income Statement Location Total Cash Total Cash Flow Hedges AOCI derivative loss at March 31, 2016 $ (26 ) $ (26 ) Reclassifications from AOCI to net income Interest expense 1 — AOCI derivative loss at June 30, 2016 $ (25 ) $ (26 ) Total Cash Flow Hedge OCI Activity, Net of Income Tax Generation Exelon Six Months Ended June 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 ) (4 ) Reclassifications from AOCI to net income Interest Expense (3 ) (a) (3 ) (a) Accumulated OCI derivative loss at June 30, 2016 $ (25 ) $ (26 ) Total Cash Flow Hedge OCI Activity, Net of Income Tax Generation Exelon Three Months Ended June 30, 2015 Income Statement Location Total Cash Total Cash Flow Hedges AOCI derivative loss at March 31, 2015 $ (23 ) $ (22 ) Effective portion of changes in fair value — 1 Reclassifications from AOCI to net income Interest Expense 2 2 AOCI derivative loss at June 30, 2015 $ (21 ) $ (19 ) Total Cash Flow Hedge OCI Activity, Net of Income Tax Generation Exelon Six Months Ended June 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 (6 ) (10 ) Reclassifications from AOCI to net income Other, net — 16 (b) Reclassifications from AOCI to net income Interest Expense 5 5 Reclassifications from AOCI to net income Operating Revenues (2 ) (2 ) Accumulated OCI derivative loss at June 30, 2015 $ (21 ) $ (19 ) __
Other Derivatives - Gain (loss) and reclassification	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 June 30, Six Months Ended June 30, 2016 2015 2016 2015 Change in fair value of commodity positions $ 5 $ 7 $ 14 $ 8 Reclassification to realized at settlement of commodity positions (5 ) (7 ) (11 ) (5 ) Net commodity mark-to-market gains (losses) — — 3 3 Change in fair value of treasury positions — — (2 ) 4 Reclassification to realized at settlement of treasury positions (1 ) (2 ) 1 (6 ) Net treasury mark-to-market gains (losses) (1 ) (2 ) (1 ) (2 ) Total net mark-to-market gains (losses) $ (1 ) $ (2 ) $ 2 $ 1 Cr Generation Exelon Six Months Ended June 30, 2016 Operating Revenues Purchased Power and Fuel Total Total Change in fair value of commodity positions $ (153 ) $ 109 $ (44 ) $ (44 ) Reclassification to realized at settlement of commodity positions (392 ) 243 (149 ) (149 ) Net commodity mark-to-market gains (losses) (545 ) 352 (193 ) (193 ) Change in fair value of treasury positions (4 ) — (4 ) (4 ) Reclassification to realized at settlement of treasury positions (4 ) — (4 ) (4 ) Net treasury mark-to-market gains (losses) (8 ) — (8 ) (8 ) Net mark-to-market gains (losses) $ (553 ) $ 352 $ (201 ) $ (201 ) Generation Exelon Corporate Exelon Three Months Ended June 30, 2015 Operating Revenues Purchased Power and Fuel Total Interest Total Change in fair value of commodity positions $ 197 $ 110 $ 307 $ — $ 307 Reclassification to realized at settlement of commodity positions (167 ) 100 (67 ) — (67 ) Net commodity mark-to-market gains (losses) 30 210 240 — 240 Change in fair value of treasury positions (3 ) — (3 ) 114 111 Reclassification to realized at settlement of treasury positions (2 ) — (2 ) 64 62 Net treasury mark-to-market gains (losses) (5 ) — (5 ) 178 173 Net mark-to-market gains (losses) $ 25 $ 210 $ 235 $ 178 $ 413 Generation Exelon Corporate Exelon Six Months Ended June 30, 2015 Operating Revenues Purchased Power and Fuel Total Interest Total Change in fair value of commodity positions $ 377 $ 15 $ 392 $ — $ 392 Reclassification to realized at settlement of commodity positions (204 ) 203 (1 ) — (1 ) Net commodity mark-to-market gains (losses) 173 218 391 — 391 Change in fair value of treasury positions 10 — 10 36 46 Reclassification to realized at settlement of treasury positions (4 ) — (4 ) 64 60 Net treasury mark-to-market gains (losses) 6 — 6 100 106 Net mark-to-market gains (losses) $ 179 $ 218 $ 397 $ 100 $ 497 Prop
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 June 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 $26 million , $40 million , $36 million , $50 million , $15 million , and $8 million as of June 30, 2016 , respectively. Rating as of June 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 $ 965 $ 12 $ 953 1 $ 356 Non-investment grade 55 24 31 — — No external ratings Internally rated — investment grade 373 1 372 — — Internally rated — non-investment grade 46 7 39 — — Total $ 1,439 $ 44 $ 1,395 1 $ 356 Net Credit Exposure by Type of Counterparty As of June 30, 2016 Financial institutions $ 96 Investor-owned utilities, marketers, power producers 573 Energy cooperatives and municipalities 696 Other 30 Total $ 1,395 _____ (a) As of June 30, 2016 , credit collateral held from counterparties where Generation had credit exposure included $9 million of cash and $35 million of letters of credit. 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 June 30, 2016 December 31, 2015 Gross Fair Value of Derivative Contracts Containing this Feature (a) $ (912 ) $ (932 ) Offsetting Fair Value of In-the-Money Contracts Under Master Netting Arrangements (b) 657 684 Net Fair Value of Derivative Contracts Containing This Feature (c) $ (255 ) $ (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)	6 Months Ended
	Jun. 30, 2016
Debt Disclosure [Abstract]
Schedule of Short-term Debt	Commercial Paper Borrowings June 30, 2016 December 31, 2015 ComEd $ 35 $ 294 BGE 208 210 PHI Corporate — 484 Pepco — 64 DPL — 105 ACE — 5
Schedule Of Issuance Of Long Term Debt	During the six months ended June 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 $ 63 Albany Green Energy biomass generation development Generation Energy Efficiency Project Financing 3.17 % February 1, 2037 $ 16 Funding to install energy conservation measures in Brooklyn, NY Generation Energy Efficiency Project Financing 3.90 % February 1, 2018 $ 7 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. Pepco Energy Efficiency Project Financing 3.30 % August 15, 2017 $ 1 Funding to install energy conservation measures for the DOE Germantown project
Retirement and Redemptions of Current and Long-Term Debt

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	Three Months Ended June 30, 2016 Successor Exelon Generation (e) ComEd PECO BGE (f) 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 2.3 (116.7) 4.8 0.3 2.0 6.1 3.5 4.8 5.9 Qualified nuclear decommissioning trust fund income 5.7 591.2 — — — — — — — Domestic production activities deduction — — — — — — — — — Health care reform legislation — — — — — — — — — Amortization of investment tax credit, net deferred taxes (1.8) (157.8) (0.2) (0.1) (0.4) (0.3) (0.1) (0.6) (1.6) Plant basis differences (d) (6.9) — (0.4) (11.3) (20.6) (7.0) (5.7) (3.5) (7.1) Production tax credits and other credits (5.8) (603.0) — — — — — — — Noncontrolling interests 0.9 94.4 — — — — — — — Statute of limitations expiration (1.7) (410.8) — — — — — — — Merger expenses 0.2 — — — — 1.0 0.2 3.1 — Other (c) (3.3) (52.3) (0.6) (5.2) (1.0) 1.0 (1.0) 1.2 7.8 Effective income tax rate 24.6% (620.0)% 38.6% 18.7% 15.0% 35.8% 31.9% 40.0% 40.0% Three Months Ended June 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 3.9 3.4 5.6 1.4 5.3 5.3 5.0 5.0 9.9 Qualified nuclear decommissioning trust fund income (1.0) (1.7) — — — — — — — Domestic production activities deduction (2.0) (3.4) — — — — — — — Health care reform legislation — — — — 0.1 — — — — Amortization of investment tax credit, net deferred taxes (0.6) (0.9) (0.3) (0.1) (0.2) (0.3) — (1.0) (0.2) Plant basis differences (1.0) — (0.1) (9.0) (0.5) (7.3) (8.3) (4.2) (0.1) Production tax credits and other credits (1.3) (2.2) — — — — — — — Noncontrolling interests (0.4) (0.6) — — — — — — — Other 1.4 2.0 0.5 0.5 0.8 1.1 (1.7) 3.7 (4.6) Effective income tax rate 34.0% 31.6% 40.7% 27.8% 40.5% 33.8% 30.0% 38.5% 40.0% Successor Predecessor Six Months Ended June 30, 2016 March 24, 2016 to June 30, 2016 January 1, 2016 to March 23, 2016 Exelon Generation ComEd PECO BGE Pepco (a) 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) 0.8 2.6 4.9 0.7 4.6 (9.5) (5.2) 5.9 5.2 11.9 Qualified nuclear decommissioning trust fund income 5.6 9.8 — — — — — — — — Domestic production activities deduction — — — — — — — — — — Health care reform legislation — — — — — — — — — — Amortization of investment tax credit, including deferred taxes on basis difference (1.7) (2.5) (0.2) (0.1) (0.1) 0.1 0.4 0.1 0.1 (0.9) Plant basis differences (d) (6.3) — (0.3) (10.2) (4.5) 12.6 2.0 1.0 1.7 (13.5) Production tax credits and other credits (5.5) (9.6) — — — — — — — — Noncontrolling interests 0.7 1.2 — — — — — — — — Statute of limitations expiration (1.0) (3.9) — — — — — — — Merger expenses 14.5 — — — — (36.1) (30.5) (17.7) (18.9) 11.1 Other (c) (2.8) (3.8) (0.1) (2.4) 0.1 (0.5) (0.1) (0.1) — 3.6 Effective income tax rate 39.3% 28.8% 39.3% 23.0% 35.1% 1.6% 1.6% 24.2% 23.1% 47.2% Six Months Ended June 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 3.2 3.0 5.3 1.3 5.3 6.4 4.1 5.5 5.5 Qualified nuclear decommissioning trust fund income 0.6 0.9 — — — — — — — Domestic production activities deduction (2.1) (3.4) — — — — — — — Health care reform legislation — — — — 0.2 — — — — Amortization of investment tax credit, including deferred taxes on basis difference (0.8) (1.1) (0.3) (0.1) (0.1) (0.4) — (0.4) (0.9) Plant basis differences (1.1) — (0.2) (7.5) (0.3) (6.1) (8.2) (1.5) (1.7) Production tax credits and other credits (1.6) (2.5) — — — — — — — Noncontrolling interests (0.6) (0.8) — — — — — — — Other 0.8 0.6 0.4 0.2 — (0.3) (0.3) 0.8 (0.4) Effective income tax rate 33.4% 31.7% 40.2% 28.9% 40.1% 34.6% 30.6% 39.4% 37.5%

Nuclear Decommissioning (Tables

Nuclear Decommissioning (Tables) - Exelon Generation Co L L C [Member]	6 Months Ended
	Jun. 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 June 30, 2016 : Nuclear decommissioning ARO at December 31, 2015 (a) $ 8,246 Accretion expense 215 Net increase due to changes in, and timing of, estimated cash flows 444 Costs incurred to decommission retired plants (2 ) Nuclear decommissioning ARO at June 30, 2016 (a) $ 8,903 _________ (a) Includes $11 million and $7 million for the current portion of the ARO at June 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 six months ended June 30, 2016 and 2015 : Exelon and Generation Exelon and Generation Three Months Ended June 30, Six Months Ended June 30, 2016 2015 2016 2015 Net unrealized gains (losses) on decommissioning trust funds — Regulatory Agreement Units (a) $ 52 $ (133 ) $ 131 $ (85 ) Net unrealized gains (losses) on decommissioning trust funds — Non-Regulatory Agreement Units (b)(c) 48 (96 ) 100 (56 ) _________ (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 $1 million of net unrealized gain related to the Zion Station pledged assets for the three months ended June 30, 2016 . Excludes $3 million and $9 million of net unrealized gain related to the Zion Station pledged assets for the six months ended June 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	June 30, 2016 and December 31, 2015 : Exelon and Generation June 30, 2016 December 31, 2015 Carrying value of Zion Station pledged assets $ 161 $ 206 Payable to Zion Solutions (a) 148 189 Current portion of payable to Zion Solutions (b) 94 99 Cumulative withdrawals by Zion Solutions to pay decommissioning costs (c) 834 786 _________ (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)	6 Months Ended
	Jun. 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, 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 six months ended June 30, 2016 and 2015 . Three Months Ended June 30, Six Months Ended June 30, Pension and Other Postretirement Benefit Costs 2016 2015 2016 2015 Exelon $ 160 $ 160 $ 297 $ 317 Generation 55 68 109 133 ComEd 42 51 83 103 PECO 8 10 17 19 BGE 18 17 33 33 BSC (a) 10 14 24 29 Pepco (b) 7 7 16 15 DPL (b) 4 4 9 8 ACE (b) 4 4 8 8 PHISCO (a)(b) 12 9 21 17 Successor Predecessor Successor Predecessor Pension and Other Postretirement Benefit Costs Three Months Ended June 30, 2016 Three Months Ended June 30, 2015 March 24, 2016 to June 30, 2016 January 1, 2016 to March 23, 2016 Six Months Ended June 30, 2015 PHI $ 27 $ 24 $ 31 $ 23 $ 48 _________ (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 six months ended June 30, 2016 and 2015 : Three Months Ended June 30, Six Months Ended June 30, Savings Plan Matching Contributions 2016 2015 2016 2015 Exelon $ 30 $ 38 $ 56 $ 60 Generation 13 20 25 33 ComEd 7 8 13 13 PECO 2 3 4 4 BGE 2 3 3 5 BSC (a) 2 4 7 5 Pepco (b) 1 1 2 2 DPL (b) — 1 1 1 PHISCO (a)(b) 2 1 3 3 ACE (b) 1 1 1 1 Successor Predecessor Successor Predecessor Savings Plan Matching Contributions Three Months Ended June 30, 2016 Three Months Ended June 30, 2015 March 24, 2016 to June 30, 2016 January 1, 2016 to March 23, 2016 Six Months Ended June 30, 2015 PHI $ 4 $ 4 $ 4 $ 3 $ 7 _________ (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 six months ended June 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 six months ended June 30, 2016 .
Schedule of Net Benefit Costs [Table Text Block]	Pension Benefits Other Postretirement Benefits 2016 2015 2016 2015 Service cost $ 91 $ 81 $ 28 $ 29 Interest cost 212 178 48 42 Expected return on assets (292 ) (256 ) (42 ) (37 ) Amortization of: Prior service cost (benefit) 4 4 (47 ) (44 ) Actuarial loss 142 142 16 21 Net periodic benefit cost $ 157 $ 149 $ 3 $ 11 Pension Benefits Other Postretirement Benefits 2016 (a) 2015 2016 (a) 2015 Components of net periodic benefit cost: Service cost $ 170 $ 163 $ 54 $ 59 Interest cost 403 355 90 83 Expected return on assets (555 ) (513 ) (80 ) (75 ) Amortization of: Prior service cost (benefit) 7 7 (91 ) (88 ) Actuarial loss 269 285 30 41 Net periodic benefit cost $ 294 $ 297 $ 3 $ 20 _______ (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 June 30, 2015 Six Months Ended June 30, 2015 January 1, 2016 to March 23, 2016 Three Months Ended June 30, 2015 Six Months Ended June 30, 2015 Service cost $ 12 $ 14 $ 28 $ 1 $ 1 $ 3 Interest cost 26 27 54 6 6 12 Expected return on assets (30 ) (35 ) (70 ) (5 ) (5 ) (11 ) Amortization of: Prior service cost (benefit) — 1 1 (3 ) (3 ) (6 ) Actuarial loss 14 17 33 2 1 4 Net periodic benefit cost $ 22 $ 24 $ 46 $ 1 $ — $ 2

Severance (Tables)

Severance (Tables)	6 Months Ended
	Jun. 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 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) 129 56 1 — — 54 1 1 — Payments (19 ) (4 ) (1 ) — — (11 ) — — — Balance at June 30, 2016 $ 145 $ 75 $ 3 $ — $ 1 $ 43 $ 1 $ 1 $ — ______________ (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 June 30, 2016 for PHI, Pepco, DPL and ACE. Exelon Generation ComEd PECO BGE Six Months Ended June 30, 2016 Severance benefits (a) $ 17 $ 12 $ 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 six months ended June 30, 2016 .
Restructuring and Related Costs	Three Months Ended June 30, Six Months Ended June 30, Acquisition, Integration and Financing Costs (a) 2016 2015 2016 2015 Exelon (b) $ 1 $ (87 ) $ 103 $ 21 Generation 4 7 20 15 ComEd (c) 1 3 (7 ) 6 PECO 1 1 2 2 BGE (d) (5 ) 1 (4 ) 3 Pepco (d) (4 ) 1 23 2 DPL (d) — 1 16 1 ACE 2 1 15 1 Successor Predecessor Successor Predecessor Acquisition, Integration and Financing Costs (a) Three Months Ended Three Months Ended March 24, 2016 to June 30, 2016 January 1, 2016 to March 23, 2016 Six Months Ended June 30, 2015 PHI (d) $ (1 ) $ 5 $ 55 $ 29 $ 14 ______________ (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 six months ended June 30, 2016 , includes the reversal of previously incurred acquisition, integration and financing costs of $8 million incurred at ComEd that has been deferred and recorded as a regulatory asset Successor Exelon Generation ComEd PECO BGE PHI Pepco (b) DPL (c) ACE Three Months Ended June 30, 2016 Severance benefits (a) $ 2 $ (1 ) $ (1 ) $ — $ — $ 4 $ 2 $ 1 $ 1 Six Months Ended June 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 $(1) million , $(1) million , less than $1 million , less than $1 million , $2 million , $1 million and $1 million , respectively, for amounts billed by BSC and/or PHISCO through intercompany allocations for the three months ended June 30, 2016 , and $8 million , $2 million , $1 million , $1 million , $19 million , $11 million and $10 million for the six months ended June 30, 2016 . Exelon Generation (a) ComEd Three Months Ended June 30, 2016 $ 2 $ 1 $ 1 June 30, 2015 1 1 — Six Months Ended June 30, 2016 $ 4 $ 3 $ 1 June 30, 2015 21 21 —
Schedule of Restructuring Reserve by Type of Cost [Table Text Block]	Amounts included in the table below represent the severance liability recorded 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) 129 56 1 — — 54 1 1 — Payments (19 ) (4 ) (1 ) — — (11 ) — — — Balance at June 30, 2016 $ 145 $ 75 $ 3 $ — $ 1 $ 43 $ 1 $ 1 $ — ______________ (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 June 30, 2016 for PHI, Pepco, DPL and ACE. Exelon Generation ComEd PECO BGE Six Months Ended June 30, 2016 Severance benefits (a) $ 17 $ 12 $ 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 six months ended June 30, 2016 .

Mezzanine Equity Mezzanine Eq40

Mezzanine Equity Mezzanine Equity (Tables)	6 Months Ended
	Jun. 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 six months ended June 30, 2016 : Balance at December 31, 2015 $ 28 Cash received from noncontrolling interests 52 Release of contingency (56 ) Balance at June 30, 2016 $ 24

Changes in Accumulated Other 41

Changes in Accumulated Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2016
Changes in Accumulated Other Comprehensive Income [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	six months ended June 30, 2016 and 2015 : Six Months Ended June 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 (4 ) — (2 ) 6 (7 ) (7 ) Amounts reclassified from AOCI (b) (3 ) — 69 — — 66 Net current-period OCI (7 ) — 67 6 (7 ) 59 Ending balance $ (26 ) $ 3 $ (2,498 ) $ (34 ) $ (10 ) $ (2,565 ) Generation (a) Beginning balance $ (21 ) $ 1 $ — $ (40 ) $ (3 ) $ (63 ) OCI before reclassifications (1 ) — — 6 (4 ) 1 Amounts reclassified from AOCI (b) (3 ) — — — — (3 ) Net current-period OCI (4 ) — — 6 (4 ) (2 ) Ending balance $ (25 ) $ 1 $ — $ (34 ) $ (7 ) $ (65 ) 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 ) Six Months Ended June 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 (10 ) — (29 ) (9 ) — (48 ) Amounts reclassified from AOCI (b) 19 — 87 — — 106 Net current-period OCI 9 — 58 (9 ) — 58 Ending balance $ (19 ) $ 3 $ (2,582 ) $ (28 ) $ — $ (2,626 ) Generation (a) Beginning balance $ (18 ) $ 1 $ — $ (19 ) $ — $ (36 ) OCI before reclassifications (6 ) 1 — (9 ) — (14 ) Amounts reclassified from AOCI (b) 3 — — — — 3 Net current-period OCI (3 ) 1 — (9 ) — (11 ) Ending balance $ (21 ) $ 2 $ — $ (28 ) $ — $ (47 ) 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) — — 4 — — 4 Net current-period OCI — — 4 — — 4 Ending balance $ (9 ) $ — $ (33 ) $ — $ — $ (42 ) ________ (a) All amounts are net of tax. 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 six months ended June 30, 2016 and 2015 . Three Months Ended June 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) (75 ) — Total before tax (56 ) — Tax benefit 22 — Net of tax $ (34 ) $ — Total Reclassifications for the period $ (34 ) $ — Comprehensive income Six Months Ended June 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) $ 38 $ — $ — Actuarial losses (b) (151 ) — (1 ) Total before tax (113 ) — (1 ) Tax benefit 44 — — Net of tax $ (69 ) $ — $ (1 ) Total Reclassifications $ (66 ) $ 3 $ (1 ) Comprehensive income Three Months Ended June 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 $ (2 ) $ (2 ) $ — Interest expense Total before tax (2 ) (2 ) — Tax expense — — — Net of tax $ (2 ) $ (2 ) $ — Comprehensive income Amortization of pension and other postretirement benefit plan items Prior service costs (b) $ 19 $ — $ — Actuarial losses (b) (90 ) — (3 ) Total before tax (71 ) — (3 ) Tax expense 27 — — Net of tax $ (44 ) $ — $ (3 ) Total Reclassifications for the period $ (46 ) $ (2 ) $ (3 ) Comprehensive income Six Months Ended June 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 (5 ) (5 ) — Interest expense Total before tax (29 ) (3 ) — Tax benefit 10 — — Net of tax $ (19 ) $ (3 ) $ — Comprehensive income Amortization of pension and other postretirement benefit plan items Prior service costs (b) $ 38 $ — $ — Actuarial losses (b) (180 ) — (5 ) Total before tax (142 ) — (5 ) Tax benefit 55 — 1 Net of tax $ (87 ) $ — $ (4 ) Total Reclassifications $ (106 ) $ (3 ) $ (4 ) 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 six months ended June 30, 2016 and 2015 : Three Months Ended June 30, Six Months Ended June 30, 2016 2015 2016 2015 Exelon Pension and non-pension postretirement benefit plans: Prior service benefit reclassified to periodic benefit cost $ 7 $ 8 $ 15 $ 15 Actuarial loss reclassified to periodic cost (30 ) (35 ) (60 ) (69 ) Pension and non-pension postretirement benefit plans valuation adjustment — — 1 17 Change in unrealized gain/(loss) on cash flow hedges 2 (2 ) 4 (6 ) Change in unrealized loss on equity investments 1 — 3 — Change in unrealized gain on marketable securities (1 ) 1 — 1 Total $ (21 ) $ (28 ) $ (37 ) $ (42 ) Generation Change in unrealized gain/(loss) on cash flow hedges $ 1 $ (1 ) $ 3 $ 1 Change in unrealized loss on equity investments 1 — 3 — Change in unrealized gain on marketable securities — — — 1 Total $ 2 $ (1 ) $ 6 $ 2

Earnings Per Share and Equity42

Earnings Per Share and Equity (Tables)	6 Months Ended
	Jun. 30, 2016
Earnings Per Share [Abstract]
Reconciliation of basic and diluted earnings per share	Three Months Ended June 30, Six Months Ended June 30, Exelon 2016 2015 2016 2015 Net income attributable to common shareholders $ 267 $ 638 $ 440 $ 1,331 Weighted average common shares outstanding — basic 924 863 923 862 Assumed exercise and/or distributions of stock-based awards 2 3 3 4 Weighted average common shares outstanding — diluted 926 866 926 866

Commitments and Contingencies43

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 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 June 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) $ 1,651 $ 1,580 $ 16 $ 23 $ 2 $ 1 $ — $ — $ 1 Surety bonds (b) 1,055 964 10 9 10 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 5 7 5 Total commercial commitments $ 6,399 $ 5,589 $ 226 $ 210 $ 262 $ 37 $ 14 $ 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 June 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: June 30, 2016 Total Environmental Investigation and Remediation Reserve Portion of Total Related to MGP Investigation and Remediation (a) Exelon $ 410 $ 311 Generation 66 — ComEd 277 275 PECO 35 33 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) $ 203 2017 22 2018 10 Total $ 235

Supplemental Financial Inform44

Supplemental Financial Information (Tables)	6 Months Ended
	Jun. 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 six months ended June 30, 2016 and 2015 : Three Months Ended June 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 $ 90 $ 90 $ — $ — $ — $ — $ — $ — $ — Non-regulatory agreement units 39 39 — — — — — — — Net unrealized gains on decommissioning trust funds Regulatory agreement units 52 52 — — — — — — — Non-regulatory agreement units 48 48 — — — — — — — Net unrealized gains on pledged assets Zion Station decommissioning 1 1 — — — — — — — Regulatory offset to decommissioning trust fund-related activities (b) (117 ) (117 ) — — — — — — — Total decommissioning-related activities 113 113 — — — — — — — Investment income 6 5 — — — — — — — Interest income related to uncertain income tax positions 4 — — — — — — — — AFUDC — Equity 15 — 1 2 5 7 5 1 1 Other 6 (1 ) 2 — — 4 1 2 1 Other, net $ 144 $ 117 $ 3 $ 2 $ 5 $ 11 $ 6 $ 3 $ 2 Successor Predecessor Six Months Ended June 30, 2016 March 24, 2016 to June 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 $ 122 $ 122 $ — $ — $ — $ — $ — $ — $ — $ — Non-regulatory agreement units 61 61 — — — — — — — — Net unrealized gains on decommissioning trust funds Regulatory agreement units 131 131 — — — — — — — — Non-regulatory agreement units 100 100 — — — — — — — — Net unrealized gains on pledged assets Zion Station decommissioning 3 3 — — — — — — — — Regulatory offset to decommissioning trust fund-related activities (b) (211 ) (211 ) — — — — — — — — Total decommissioning-related activities 206 206 — — — — — — — — Investment income (expense) 12 5 — (1 ) 2 (c) — — — — — Long-term lease income 4 — — — — — — — — — Interest income related to uncertain income tax positions 5 — — — — 1 — 1 — — AFUDC — Equity 24 — 3 4 9 9 2 3 8 7 Loss on debt extinguishment (3 ) (2 ) — — — — — — — Other 10 1 4 1 — 4 4 1 4 (11 ) Other, net $ 258 $ 210 $ 7 $ 4 $ 11 $ 14 $ 6 $ 5 $ 12 $ (4 ) Three Months Ended June 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 $ 93 $ 93 $ — $ — $ — $ — $ — $ — $ — Non-regulatory agreement units 74 74 — — — — — — — Net unrealized losses on decommissioning trust funds Regulatory agreement units (133 ) (133 ) — — — — — — — Non-regulatory agreement units (96 ) (96 ) — — — — — — — Regulatory offset to decommissioning trust fund-related activities (b) 28 28 — — — — — — — Total decommissioning-related activities (34 ) (34 ) — — — — — — — Investment income (expense) 1 — — (1 ) 1 (c) — — — — Long-term lease income 4 — — — — — — — — AFUDC — Equity 5 — 1 1 3 3 3 — — Other 7 3 4 1 — 9 5 2 1 Other, net $ (17 ) $ (31 ) $ 5 $ 1 $ 4 $ 12 $ 8 $ 2 $ 1 Six Months Ended June 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 $ 164 $ 164 $ — $ — $ — $ — $ — $ — $ — Non-regulatory agreement units 104 104 — — — — — — — Net unrealized losses on decommissioning trust funds Regulatory agreement units (85 ) (85 ) — — — — — — — Non-regulatory agreement units (56 ) (56 ) — — — — — — — Net unrealized gains on pledged assets Zion Station decommissioning 9 9 — — — — — — Regulatory offset to decommissioning trust fund-related activities (b) (78 ) (78 ) — — — — — — — Total decommissioning-related activities 58 58 — — — — — — — Investment income (expense) 4 1 — (1 ) 2 (c) — — — — Long-term lease income 8 — — — — — — — — Interest income related to uncertain income tax positions — 1 — — — — — — — AFUDC — Equity 11 — 1 3 7 7 6 — 1 Terminated interest rate swaps (d) (26 ) — — — — — — — — Other 9 2 8 1 (1 ) 14 7 5 2 Other, net $ 64 $ 62 $ 9 $ 3 $ 8 $ 21 $ 13 $ 5 $ 3 ____ (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) 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. (d) 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 six months ended June 30, 2016 and 2015 : Successor Predecessor Six Months Ended June 30, 2016 March 24, 2016 to June 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) $ 1,432 $ 674 $ 345 $ 121 $ 150 $ 85 $ 55 $ 40 $ 111 $ 94 Amortization of regulatory assets (a) 166 — 34 13 56 59 21 41 63 58 Amortization of intangible assets, net (a) 28 23 — — — — — — — — Amortization of energy contract assets and liabilities (b) (7 ) (7 ) — — — — — — — — Nuclear fuel (c) 557 557 — — — — — — — — ARO accretion (d) 220 220 — — — — — — — — Total depreciation, amortization, accretion and depletion $ 2,396 $ 1,467 $ 379 $ 134 $ 206 $ 144 $ 76 $ 81 $ 174 $ 152 Six Months Ended June 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Depreciation, amortization, accretion and depletion Property, plant and equipment (a) $ 1,087 $ 485 $ 312 $ 119 $ 143 $ 193 $ 81 $ 50 $ 38 Amortization of regulatory assets (a) 101 — 40 12 49 114 44 24 48 Amortization of intangible assets, net (a) 24 24 — — — — — — — Amortization of energy contract assets and liabilities (b) — 1 — — — — — — — Nuclear fuel (c) 552 552 — — — — — — — ARO accretion (d) 193 193 — — — — — — — Total depreciation, amortization, accretion and depletion $ 1,957 $ 1,255 $ 352 $ 131 $ 192 $ 307 $ 125 $ 74 $ 86 ________ (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 Six Months Ended June 30, 2016 March 24, 2016 to June 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 $ 297 $ 109 $ 83 $ 17 $ 33 $ 16 $ 9 $ 8 $ 31 $ 23 Loss from equity method investments 10 11 — — — — — — — — Provision for uncollectible accounts 51 13 18 10 3 8 8 10 7 16 Stock-based compensation costs 67 — — — — — — — — 3 Other decommissioning-related activity (a) (123 ) (123 ) — — — — — — — — Energy-related options (b) (17 ) (17 ) — — — — — — — — Amortization of regulatory asset related to debt costs 4 — 2 1 — 1 — — 1 1 Amortization of rate stabilization deferral 34 — — — 34 (2 ) 2 — — 5 Amortization of debt fair value adjustment (6 ) (6 ) — — — — — — — — Discrete impacts from EIMA (c) (21 ) — (21 ) — — — — — — — Amortization of debt costs 14 10 2 1 2 — — — — — Provision for excess and obsolete inventory 68 66 2 — — 1 1 1 — 1 Merger-related commitments (d)(e) 503 3 — — — 138 100 120 358 — Severance costs 122 50 — — — — — — 54 — Asset retirement costs — — — — — — 4 2 — — Lower of cost or market inventory adjustment 36 36 — — — — — — — — Other 17 17 (3 ) (2 ) (12 ) (4 ) (3 ) (3 ) (7 ) (3 ) Total other non-cash operating activities $ 1,056 $ 169 $ 83 $ 27 $ 60 $ 158 $ 121 $ 138 $ 444 $ 46 Non-cash investing and financing activities: Change in capital expenditures not paid $ (364 ) $ (317 ) $ (21 ) $ (12 ) $ 2 $ 11 $ (9 ) $ 6 $ (4 ) $ 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) — — — — — — — — 127 — 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 471 471 — — — — — — — — Indemnification of like-kind exchange position (g) — — 5 — — — — — — — Non-cash financing of capital projects 60 60 — — — — — — — — Six Months Ended June 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Other non-cash operating activities: Pension and non-pension postretirement benefit costs $ 317 $ 133 $ 103 $ 19 $ 33 $ 48 $ 15 $ 8 $ 8 Loss from equity method investments 2 3 — — — — — — — Provision for uncollectible accounts 80 11 35 24 11 30 9 12 9 Stock-based compensation costs 79 — — — — 6 — — — Other decommissioning-related activity (a) (50 ) (50 ) — — — — — — — Energy-related options (b) 27 27 — — — — — — — Amortization of regulatory asset related to debt costs — — — — — 2 1 — — Amortization of rate stabilization deferral 40 — — — 40 9 8 1 — Amortization of debt fair value adjustment (37 ) (6 ) — — — — — — — Discrete impacts from EIMA (c) 77 — 77 — — — — — — Amortization of debt costs 35 8 2 1 1 1 — — — Provision for excess and obsolete inventory — — — — — 1 — — — Lower of cost or market inventory adjustment 13 13 — — — — — — — Other (4 ) (5 ) 5 1 (9 ) 4 — 1 — Total other non-cash operating activities $ 579 $ 134 $ 222 $ 45 $ 76 $ 101 $ 33 $ 22 $ 17 Non-cash investing and financing activities: Indemnification of like-kind exchange position (g) — — 3 — — — — — — 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 June 30, 2016 and December 31, 2015 : Successor June 30, 2016 Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Property, plant and equipment: Accumulated depreciation and amortization $ 17,340 (a) $ 9,179 (a) $ 3,785 $ 3,185 $ 3,161 $ 83 $ 2,995 $ 1,157 $ 998 Accounts receivable: Allowance for uncollectible accounts $ 314 $ 82 $ 74 $ 75 $ 33 $ 50 $ 16 $ 17 $ 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 $2,936 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 six months ended June 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 June 30, 2016 Successor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Utility taxes $ 217 $ 27 $ 60 $ 32 $ 21 $ 77 $ 73 $ 4 $ — Successor Predecessor Six Months Ended June 30, 2016 March 24, 2016 to June 30, 2016 January 1, 2016 to March 23, 2016 Exelon Generation ComEd PECO BGE Pepco DPL ACE PHI PHI Utility taxes $ 369 $ 55 $ 119 $ 66 $ 45 $ 152 $ 9 $ — $ 84 $ 77 Three Months Ended June 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Utility taxes $ 132 $ 24 $ 55 $ 32 $ 21 $ 81 $ 77 $ 4 $ — Six Months Ended June 30, 2015 Predecessor Exelon Generation ComEd PECO BGE PHI Pepco DPL ACE Utility taxes $ 279 $ 51 $ 117 $ 67 $ 44 $ 166 $ 157 $ 9 $ —

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 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 six months ended June 30, 2016 and 2015 is as follows: Three Months Ended June 30, 2016 and 2015 Successor Generation (a) ComEd PECO BGE PHI (b) Other (c) Intersegment Exelon Operating revenues (d) : 2016 Competitive businesses electric revenues $ 3,655 $ — $ — $ — $ — $ — $ (354 ) $ 3,301 Competitive businesses natural gas revenues 367 — — — — — — 367 Competitive businesses other revenues (433 ) — — — — — (1 ) (434 ) Rate-regulated electric revenues — 1,286 587 584 1,030 — (7 ) 3,480 Rate-regulated natural gas revenues — — 77 96 26 — (2 ) 197 Shared service and other revenues — — — — 10 398 (409 ) (1 ) 2015 Competitive businesses electric revenues $ 3,663 $ — $ — $ — $ — $ — $ (151 ) $ 3,512 Competitive businesses natural gas revenues 431 — — — — — — 431 Competitive businesses other revenues 138 — — — — — (1 ) 137 Rate-regulated electric revenues — 1,148 582 541 — — (1 ) 2,270 Rate-regulated natural gas revenues — — 79 87 — — (1 ) 165 Shared service and other revenues — — — — — 340 (341 ) (1 ) Intersegment revenues (e) : 2016 $ 355 $ 3 $ 2 $ 4 $ 10 $ 398 $ (771 ) $ 1 2015 152 1 — 1 — 340 (493 ) 1 Net income (loss): 2016 $ 28 $ 145 $ 100 $ 34 $ 52 $ (52 ) $ (1 ) $ 306 2015 390 99 70 47 — 28 (1 ) 633 Total assets: June 30, 2016 $ 46,897 $ 28,105 $ 10,586 $ 8,325 $ 20,921 $ 10,069 $ (12,125 ) $ 112,778 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 six months ended June 30, 2016 include revenue from sales to PECO of $143 million and sales to BGE of $306 million in the Mid-Atlantic region, and sales to ComEd of $18 million in the Midwest region. For the six months ended June 30, 2015 , intersegment revenues for Generation include revenue from sales to PECO of $112 million and sales to BGE of $235 million in the Mid-Atlantic region, and sales to ComEd of $15 million in the Midwest region. For the Successor period of March 24, 2016 to June 30, 2016 , intersegment revenues for Generation include revenue from sales to Pepco of $94 million , sales to DPL of $47 million , and sales to ACE of $13 million in the Mid-Atlantic region. (b) Amounts included represent activity for the PHI's successor period, March 24, 2016 through June 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 six months ended June 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 June 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: Six Months Ended June 30, 2016 Six Months Ended June 30, 2015 Revenues (a) Intersegment Total Revenues (a)(c) Intersegment (c) Total (c) Mid-Atlantic $ 2,964 $ (28 ) $ 2,936 $ 2,920 $ (61 ) $ 2,859 Midwest 2,166 13 2,179 2,482 — 2,482 New England 823 (2 ) 821 1,232 (6 ) 1,226 New York 573 (24 ) 549 529 (1 ) 528 ERCOT 370 — 370 375 (3 ) 372 Other Power Regions 456 (9 ) 447 522 (19 ) 503 Total Revenues for Reportable Segments 7,352 (50 ) 7,302 8,060 (90 ) 7,970 Other (b) 977 50 1,027 2,014 90 2,104 Total Generation Consolidated Operating Revenues $ 8,329 $ — $ 8,329 $ 10,074 $ — $ 10,074 __________ (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. Also includes an $11 million and a $22 million increase to revenues for the amortization of intangible assets related to commodity contracts recorded at fair value for the six months ended June 30, 2016 and 2015 , respectively, unrealized mark-to-market losses of $553 million and gains of $179 million for the six months ended June 30, 2016 and 2015 , respectively, and elimination of intersegment revenues. (c) Exelon corrected an error in the June 30, 2015 balances within Intersegment Revenue and Revenue from external customers for an overstatement of $89 million of Intersegment Revenue for Reportable Segments for the six months ended June 30, 2015 , an understatement of Revenue from external customers for Reportable Segments of $89 million for the six months ended June 30, 2015 , an understatement of $89 million of Intersegment Revenue for Other for the six months ended June 30, 2015 , and an overstatement of Revenue from external customers for Other of $89 million for the six months ended June 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: Six Months Ended June 30, 2016 Six Months Ended June 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 $ 1,661 $ 8 $ 1,669 $ 1,690 $ (11 ) $ 1,679 Midwest 1,443 6 1,449 1,454 (6 ) 1,448 New England 204 (13 ) 191 277 (31 ) 246 New York 408 (13 ) 395 306 28 334 ERCOT 192 (54 ) 138 179 (54 ) 125 Other Power Regions 211 (37 ) 174 185 (77 ) 108 Total Revenues net of purchased power and fuel expense for Reportable Segments 4,119 (103 ) 4,016 4,091 (151 ) 3,940 Other (b) 190 103 293 701 151 852 Total Generation Revenues net of purchased power and fuel expense $ 4,309 $ — $ 4,309 $ 4,792 $ — $ 4,792
Exelon Generation Co L L C [Member]
Segment Reporting Information [Line Items]
Analysis and reconciliation of reportable segment revenues for Generation	Three Months Ended June 30, 2016 Three Months Ended June 30, 2015 RNF (a) Intersegment RNF Total RNF RNF (a)(c) Intersegment RNF (c) Total RNF (c) Mid-Atlantic $ 830 $ (2 ) $ 828 $ 891 $ 1 $ 892 Midwest 724 4 728 750 (5 ) 745 New England 118 (8 ) 110 95 (7 ) 88 New York 270 (3 ) 267 138 7 145 ERCOT 111 (34 ) 77 91 (21 ) 70 Other Power Regions 123 (27 ) 96 113 (51 ) 62 Total Revenues net of purchased power and fuel for Reportable Segments 2,176 (70 ) 2,106 2,078 (76 ) 2,002 Other (b) (164 ) 70 (94 ) 305 76 381 Total Generation Revenues net of purchased power and fuel expense $ 2,012 $ — $ 2,012 $ 2,383 $ — $ 2,383 __________ (a) Includes purchases and sales from 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. Also includes a $12 million decrease and a $14 million decrease to RNF for the amortization of intangible assets related to commodity contracts for the three months ended June 30, 2016 and 2015 , respectively, unrealized mark-to-market losses of $304 million and gains of $235 million for the three months ended June 30, 2016 and 2015 , respectively, accelerated nuclear fuel amortization associated with nuclear decommissioning as discussed at Note 7 - Early Nuclear Plant Retirements of the Combined Notes to Consolidated Financial Statements of $9 million for the three months ended June 30, 2016 , and the elimination of intersegment revenue net of purchased power and fuel expense. (c) Exelon corrected an error in the June 30, 2015 balances within Intersegment RNF and RNF from external customers for an understatement of $6 million of Intersegment RNF for Reportable Segments for the three months ended June 30, 2015 , and an overstatement of $6 million of Intersegment RNF for Other for the three months ended June 30, 2015 . This also included an understatement of total RNF for Reportable Segments and an overstatement of total RNF for Other of $6 million for the three months ended June 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 June 30, 2016 Three Months Ended June 30, 2015 Revenues (a) Intersegment Total Revenues (a)(c) Intersegment (c) Total (c) Mid-Atlantic $ 1,432 $ (16 ) $ 1,416 $ 1,364 $ (18 ) $ 1,346 Midwest 1,076 7 1,083 1,206 — 1,206 New England 352 (1 ) 351 367 — 367 New York 356 (10 ) 346 222 (4 ) 218 ERCOT 207 — 207 194 (2 ) 192 Other Power Regions 232 (9 ) 223 310 (21 ) 289 Total Revenues for Reportable Segments 3,655 (29 ) 3,626 3,663 (45 ) 3,618 Other (b) (66 ) 29 (37 ) 569 45 614 Total Generation Consolidated Operating Revenues $ 3,589 $ — $ 3,589 $ 4,232 $ — $ 4,232 __________ (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. Also includes a $9 million decrease and $17 million decrease to revenues for the amortization of intangible assets related to commodity contracts recorded at fair value for the three months ended June 30, 2016 and 2015 , respectively, unrealized mark-to-market losses of $615 million and gains of $25 million for the three months ended June 30, 2016 and 2015 , respectively, and elimination of intersegment revenues. (c) Exelon corrected an error in the June 30, 2015 balances within Intersegment Revenue and Revenue from external customers for an overstatement of $46 million of Intersegment Revenue for Reportable Segments for the three months ended June 30, 2015 , an understatement of Revenue from external customers for Reportable Segments of $46 million for the three months ended June 30, 2015 , an understatement of $46 million of Intersegment Revenue for Other for the three months ended June 30, 2015 , and an overstatement of Revenue from external customers for Other of $46 million for the three months ended June 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 ($)	Mar. 31, 2016	Jun. 30, 2016	Mar. 23, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Jan. 01, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net Cash Provided by (Used in) Financing Activities					$ 1,469,000,000	$ 3,713,000,000
Net Cash Provided by (Used in) Operating Activities					4,553,000,000	3,969,000,000
Pepco Holdings LLC [Member] | Predecessor [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Interest				$ 1,000,000		1,000,000
Net Cash Provided by (Used in) Financing Activities			$ 372,000,000			233,000,000
Net Cash Provided by (Used in) Operating Activities			$ 264,000,000			339,000,000
Pepco Holdings LLC [Member] | Successor [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Quantifying Misstatement in Current Year Financial Statements, Amount	$ 46,000,000
Net Cash Provided by (Used in) Financing Activities	135,000,000	$ 137,000,000
Net Cash Provided by (Used in) Operating Activities	$ 3,000,000	$ 188,000,000
Delmarva Power and Light Company [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Interest				1,000,000
Net Cash Provided by (Used in) Financing Activities					(30,000,000)	35,000,000
Net Cash Provided by (Used in) Operating Activities					220,000,000	115,000,000
Atlantic City Electric 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, 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				4,000,000		1,000,000
Net Cash Provided by (Used in) Financing Activities					100,000,000	58,000,000
Net Cash Provided by (Used in) Operating Activities					208,000,000	83,000,000
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		1,000,000
Net Cash Provided by (Used in) Financing Activities					64,000,000	159,000,000
Net Cash Provided by (Used in) Operating Activities					$ 365,000,000	$ 105,000,000

Variable Interest Entities - Na

Variable Interest Entities - Narrative (Details)	3 Months Ended		6 Months Ended		9 Months Ended
	Jun. 30, 2016USD ($)VIE	Jun. 30, 2015USD ($)	Jun. 30, 2016USD ($)VIE	Jun. 30, 2015USD ($)	Sep. 30, 2015USD ($)	Dec. 31, 2015USD ($)VIE	Jul. 31, 2014USD ($)	Apr. 01, 2014USD ($)
Variable Interest Entity [Line Items]
Other Commitment	$ 6,399,000,000		$ 6,399,000,000
Variable Interest Entity, Financial or Other Support, Amount			$ 13,000,000
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			19,000,000
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	$ 5,589,000,000		$ 5,589,000,000				$ 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			$ 4,000,000
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	262,000,000		262,000,000
Payments for Restructuring			0
Baltimore Gas and Electric Company [Member] | RSB Bond Co LLC [Member]
Variable Interest Entity [Line Items]
Cash Remitted To VIE	21,000,000	$ 21,000,000	42,000,000	$ 42,000,000
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	1,000,000		1,000,000			$ 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	12,000,000	$ 14,000,000	26,000,000	$ 27,000,000
Constellation Energy Nuclear Group [Member] | Exelon Generation Co L L C [Member]
Variable Interest Entity [Line Items]
Due from Affiliates	308,000,000		308,000,000					$ 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		Jun. 30, 2016		Dec. 31, 2015
Variable Interest Entity [Line Items]
Current Assets	[2]	$ 818	[1]	$ 909
Non Current Assets	[2]	8,083	[1]	8,009
Total Assets	[2]	8,901	[1]	8,918
Current Liabilities	[2]	597	[1]	473
Non Current Liabilities	[2]	3,070	[1]	2,927
Total Liabilities	[2]	3,667	[1]	3,400
Assets		112,778		95,384
Total liabilities	[3]	85,456		68,062
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets		8,240		8,268
Total liabilities		3,461		3,264
Exelon Generation Co L L C [Member]
Variable Interest Entity [Line Items]
Current Assets		784	[1]	881
Non Current Assets		8,048	[1]	8,004
Total Assets		8,832	[1]	8,885
Current Liabilities		464	[1]	387
Non Current Liabilities		2,951	[1]	2,884
Total Liabilities		3,415	[1]	3,271
Assets		46,897		46,529
Total liabilities	[4]	33,530		33,559
Exelon Generation Co L L C [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets		8,172		8,235
Total liabilities		3,211		3,135
Baltimore Gas and Electric Company [Member]
Variable Interest Entity [Line Items]
Current Assets		17		23
Non Current Assets		3		3
Total Assets		20		26
Current Liabilities		82		81
Non Current Liabilities		0		41
Total Liabilities		82		122
Assets		8,325		8,295
Total liabilities	[5]	5,395		5,418
Baltimore Gas and Electric Company [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets		20		26
Total liabilities		82		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		14
Non Current Assets		31
Total Assets		45
Current Liabilities		48
Non Current Liabilities		118
Total Liabilities		166
Assets		20,921
Total liabilities		13,150
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		45
Total liabilities		166
Atlantic City Electric Company [Member]
Variable Interest Entity [Line Items]
Current Assets		10		12
Non Current Assets		19		18
Total Assets		29		30
Current Liabilities		44		48
Non Current Liabilities		106		124
Total Liabilities		150		172
Assets		3,461		3,387
Total liabilities		2,430		2,387
Atlantic City Electric Company [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets		29		30
Total liabilities		$ 150		$ 172
[1]	.
[2]	Includes certain purchase accounting adjustments not pushed down to the BGE standalone entity.
[3]	Exelon’s consolidated assets include $8,240 million and $8,268 million at June 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 $3,461 million and $3,264 million at June 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 $8,172 million and $8,235 million at June 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 $3,211 million and $3,135 million at June 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 $20 million and $26 million at June 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 $82 million and $122 million at June 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		Jun. 30, 2016	Mar. 23, 2016	Dec. 31, 2015		Jun. 30, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Cash and cash equivalents		$ 1,647		$ 6,502		$ 6,014	$ 1,878
Restricted cash		201		205
Accounts receivable, net
Customer		3,671		3,187
Other		988		912
Derivative Asset, Current		759		1,365
Inventory
Materials and supplies		1,183		1,104
Other current assets		1,101		752
Total current assets		11,495		15,334
Property, plant and equipment, net		70,693		57,439
Nuclear decommissioning trust funds		10,737		10,342
Goodwill		6,696		2,672
Derivative Asset, Noncurrent		546		758
Other noncurrent assets		1,366		1,445
Total assets		112,778		95,384
Short-term borrowings		951		533
Long-term debt due within one year		2,693		1,500
Accounts payable		2,826		2,883
Accrued expenses		2,757		2,376
Mark-to-market derivative liabilities (current liabilities)		152		205
Other current liabilities		508		100
Other		1,025		842
Total current liabilities		11,894		9,118
Long-term debt		31,541		23,645
Asset retirement obligations		9,256		8,585
Pension obligation(c)		3,767		3,385
Energy Marketing Contract Liabilities, Noncurrent		1,011		117
Other noncurrent liabilities		1,876		1,491
Total liabilities	[1]	85,456		68,062
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		138		164
Restricted cash		53		100
Accounts receivable, net
Customer		253		219
Other		44		43
Derivative Asset, Current		41		140
Inventory
Materials and supplies		189		181
Other current assets		37		35
Total current assets		755		882
Property, plant and equipment, net		5,147		5,160
Nuclear decommissioning trust funds		2,100		2,036
Goodwill		47		47
Derivative Asset, Noncurrent		24		53
Other noncurrent assets		167		90
Total noncurrent assets		7,485		7,386
Total assets		8,240		8,268
Long-term debt due within one year		312		111
Accounts payable		146		216
Accrued expenses		79		115
Mark-to-market derivative liabilities (current liabilities)		21		5
Other current liabilities		13		12
Other		23		13
Total current liabilities		594		472
Long-term debt		675		666
Asset retirement obligations	[2]	2,053		1,999
Pension obligation(c)		9		9
Energy Marketing Contract Liabilities, Noncurrent		31		39
Other noncurrent liabilities		99		79
Total deferred credits and other liabilities		2,867		2,792
Total liabilities		3,461		3,264
Exelon Generation Co L L C [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		373		431		456	780
Restricted cash		98		123
Accounts receivable, net
Customer		2,076		2,095
Other		325		360
Derivative Asset, Current		759		1,365
Inventory
Materials and supplies		840		880
Other current assets		735		535
Total current assets		5,725		6,342
Property, plant and equipment, net		26,656		25,843
Nuclear decommissioning trust funds		10,737		10,342
Goodwill		47		47
Derivative Asset, Noncurrent		499		733
Other noncurrent assets		632		627
Total assets		46,897		46,529
Short-term borrowings		208		29
Long-term debt due within one year		174		90
Accounts payable		1,271		1,583
Accrued expenses		743		935
Mark-to-market derivative liabilities (current liabilities)		134		182
Other current liabilities		75		100
Other		339		356
Total current liabilities		4,187		4,933
Long-term debt		7,965		7,936
Asset retirement obligations		9,081		8,431
Energy Marketing Contract Liabilities, Noncurrent		94		117
Other noncurrent liabilities		634		602
Total liabilities	[3]	33,530		33,559
Exelon Generation Co L L C [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		138		164
Restricted cash		26		77
Accounts receivable, net
Customer		253		219
Other		44		43
Derivative Asset, Current		41		140
Inventory
Materials and supplies		189		181
Other current assets		30		30
Total current assets		721		854
Property, plant and equipment, net		5,147		5,160
Nuclear decommissioning trust funds		2,100		2,036
Goodwill		47		47
Derivative Asset, Noncurrent		24		53
Other noncurrent assets		133		85
Total noncurrent assets		7,451		7,381
Total assets		8,172		8,235
Long-term debt due within one year		183		27
Accounts payable		146		216
Accrued expenses		76		113
Mark-to-market derivative liabilities (current liabilities)		21		5
Other current liabilities		13		12
Other		23		13
Total current liabilities		462		386
Long-term debt		557		623
Asset retirement obligations		2,053		1,999	[2]
Pension obligation(c)		9		9
Energy Marketing Contract Liabilities, Noncurrent		31		39
Other noncurrent liabilities		99		79
Total deferred credits and other liabilities		2,749		2,749
Total liabilities		3,211		3,135
Baltimore Gas and Electric Company [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		5		9		24	64
Restricted cash		19		24
Accounts receivable, net
Customer		289		300
Other		70		112
Inventory
Materials and supplies		41		33
Other current assets		7		3
Total current assets		714		845
Property, plant and equipment, net		6,747		6,597
Other noncurrent assets		9		8
Total assets		8,325		8,295
Short-term borrowings		208		210
Long-term debt due within one year		380		378
Accounts payable		222		209
Accrued expenses		101		110
Other		30		35
Total current liabilities		1,165		1,134
Long-term debt		1,440		1,480
Asset retirement obligations		15		17
Other noncurrent liabilities		71		61
Total liabilities	[4]	5,395		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		17		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		17		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		20		26
Long-term debt due within one year		81		79
Accounts payable		0		0
Accrued expenses		1		2
Mark-to-market derivative liabilities (current liabilities)		0		0
Other current liabilities		0		0
Other		0		0
Total current liabilities		82		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		82		122
Pepco Holdings LLC [Member] | Predecessor [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents			$ 319	26		34	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		294	$ 319
Restricted cash		44
Accounts receivable, net
Customer		501
Other		237
Derivative Asset, Current		0
Inventory
Materials and supplies		121
Other current assets		87
Total current assets		2,019
Property, plant and equipment, net		11,148
Goodwill		4,024
Derivative Asset, Noncurrent		0
Other noncurrent assets		57
Total assets		20,921
Short-term borrowings		500
Long-term debt due within one year		551
Accounts payable		344
Accrued expenses		306
Mark-to-market derivative liabilities (current liabilities)		0
Other current liabilities		433
Other		31
Total current liabilities		2,636
Long-term debt		5,522
Asset retirement obligations		12
Pension obligation(c)		0
Energy Marketing Contract Liabilities, Noncurrent		918
Other noncurrent liabilities		280
Total liabilities		13,150
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		10
Accounts receivable, net
Customer		0
Other		0
Derivative Asset, Current		0
Inventory
Materials and supplies		0
Other current assets		4
Total current assets		14
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		45
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		118
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		118
Total liabilities		166
Atlantic City Electric Company [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents		151		3		$ 3	$ 2
Restricted cash		10		12
Accounts receivable, net
Customer		122		156
Other		69		242
Inventory
Materials and supplies		23		23
Other current assets		4		12
Total current assets		513		546
Property, plant and equipment, net		2,427		2,322
Other noncurrent assets		23		19
Total assets		3,461		3,387
Short-term borrowings		0		5
Long-term debt due within one year		44		48
Accounts payable		107		96
Accrued expenses		86		70
Other		7		14
Total current liabilities		375		297
Long-term debt		1,136		1,153
Other noncurrent liabilities		23		12
Total liabilities		2,430		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		10		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		10		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		29		30
Long-term debt due within one year		42		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		44		48
Long-term debt		106		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		106		124
Total liabilities		$ 150		$ 172
[1]	Exelon’s consolidated assets include $8,240 million and $8,268 million at June 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 $3,461 million and $3,264 million at June 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 $8,172 million and $8,235 million at June 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 $3,211 million and $3,135 million at June 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 $20 million and $26 million at June 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 $82 million and $122 million at June 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		Jun. 30, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Total assets	[1]	$ 898	$ 427
Total liabilities	[1]	387	147
Exelon's ownership interest in VIE	[1]	80	11
Other ownership interests in VIE	[1]	431	269
Assets Held-in-trust, Noncurrent		161	206
Commercial Agreement Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Total assets	[1]	503	263
Total liabilities	[1]	106	22
Exelon's ownership interest in VIE	[1]	0	0
Other ownership interests in VIE	[1]	397	241
Equity Method Investment Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Total assets	[1]	395	164
Total liabilities	[1]	281	125
Exelon's ownership interest in VIE	[1]	80	11
Other ownership interests in VIE	[1]	34	28
Investments [Member]
Variable Interest Entity [Line Items]
Registrants' maximum exposure to loss		137
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		137	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]	13	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]	13	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		161	206
Payable to Zion Solutions	[3]	148	$ 189
Exelon Generation Co L L C [Member] | Investments [Member] | Maximum [Member]
Variable Interest Entity [Line Items]
Registrants' maximum exposure to loss		$ 18
[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 $161 million and $206 million as of June 30, 2016 and December 31, 2015, respectively; offset by payables to ZionSolutions LLC of $148 million and $189 million as of June 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	Mar. 31, 2017	Sep. 30, 2016	Jun. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Mar. 23, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Mar. 24, 2016	Dec. 31, 2015	Jul. 31, 2014
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent				$ 3,443,000,000	$ 3,443,000,000				$ 3,443,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets				1,441,000,000	1,441,000,000				1,441,000,000
Revenues				6,910,000,000				$ 6,514,000,000	14,485,000,000	$ 15,345,000,000
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Payments to Acquire Businesses, Gross									(6,642,000,000)	(28,000,000)
Business Combination, Integration Related Costs				1,000,000				(87,000,000)	103,000,000	21,000,000
Investments				$ 502,000,000	$ 502,000,000				$ 502,000,000			$ 639,000,000
Cash offered in exchange for each share of PHI stock				$ 27.25	$ 27.25				$ 27.25
Other noncurrent assets				$ 1,366,000,000	$ 1,366,000,000				$ 1,366,000,000			1,445,000,000
Other Commitment				6,399,000,000	6,399,000,000				6,399,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets				4,024,000,000	4,024,000,000				4,024,000,000
Business Combination, Contingent Consideration, Asset				235,000,000	235,000,000				235,000,000
Net income				306,000,000				633,000,000	430,000,000	1,372,000,000
Goodwill, Acquired During Period				8,000,000		$ 4,016,000,000
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				2,763,000,000	2,763,000,000				2,763,000,000
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
Common Stock [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Payments to Acquire Businesses, Gross							$ (180,000,000)
Scenario, Adjustment [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent				3,448,000,000	3,448,000,000				3,448,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets				1,441,000,000	1,441,000,000				1,441,000,000
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Assets				249,000,000	249,000,000				249,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities				2,764,000,000	2,764,000,000				2,764,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt				5,661,000,000	5,661,000,000				5,661,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other				187,000,000	187,000,000				187,000,000
Other Investments [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Other Commitment				130,000,000	130,000,000				130,000,000
Pepco Holdings LLC [Member]
Business Acquisition [Line Items]
Revenues				1,112,000,000					1,219,000,000
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Other Commitment				508,000,000	508,000,000				508,000,000
Net income				52,000,000					(262,000,000)
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					(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)
Other Commitment				444,000,000	444,000,000				444,000,000
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				3,589,000,000				4,232,000,000	8,329,000,000	10,074,000,000
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Payments to Acquire Businesses, Gross									(1,000,000)	(28,000,000)
Business Combination, Integration Related Costs				4,000,000				7,000,000	20,000,000	15,000,000
Investments				$ 294,000,000	$ 294,000,000				$ 294,000,000			210,000,000
Equity Method Investment, Ownership Percentage				50.01%	50.01%				50.01%
Other noncurrent assets				$ 632,000,000	$ 632,000,000				$ 632,000,000			627,000,000
Gain (Loss) on Disposition of Property Plant Equipment									32,000,000
Other Commitment				5,589,000,000	5,589,000,000				5,589,000,000				$ 91,000,000
Business Combination, Contingent Consideration, Asset				163,000,000	163,000,000				163,000,000
Net income				28,000,000				390,000,000	285,000,000	875,000,000
Members' Capital				9,168,000,000	9,168,000,000				9,168,000,000			8,997,000,000
Atlantic City Electric Company [Member]
Business Acquisition [Line Items]
Revenues				270,000,000				285,000,000	561,000,000	618,000,000
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Business Combination, Integration Related Costs				2,000,000				1,000,000	15,000,000	1,000,000
Other noncurrent assets				23,000,000	23,000,000				23,000,000			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				1,098,000,000	1,098,000,000				1,098,000,000
Net income				3,000,000				6,000,000	(97,000,000)	15,000,000
Atlantic City Electric Company [Member] | Pepco Holdings LLC [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Other Commitment				120,000,000	120,000,000				120,000,000
Equity Contribution									49,000,000
Potomac Electric Power Company [Member]
Business Acquisition [Line Items]
Revenues				509,000,000				504,000,000	1,061,000,000	1,049,000,000
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Investments				99,000,000	99,000,000				99,000,000			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				14,000,000	14,000,000				14,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets				1,691,000,000	1,691,000,000				1,691,000,000
Net income				49,000,000				42,000,000	(60,000,000)	68,000,000
Potomac Electric Power Company [Member] | Pepco Holdings LLC [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Other Commitment				139,000,000	139,000,000				139,000,000
Equity Contribution									73,000,000
Delmarva Power and Light Company [Member]
Business Acquisition [Line Items]
Revenues				281,000,000				271,000,000	643,000,000	691,000,000
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Business Combination, Integration Related Costs				0				1,000,000	16,000,000	1,000,000
Other noncurrent assets				8,000,000	8,000,000				8,000,000			$ 2,000,000
Other Commitment				11,000,000	11,000,000				11,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets				1,174,000,000	1,174,000,000				1,174,000,000
Net income				12,000,000				8,000,000	(60,000,000)	40,000,000
Delmarva Power and Light Company [Member] | Pepco Holdings LLC [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Other Commitment				104,000,000	104,000,000				104,000,000
Equity Contribution									46,000,000
Pepco Holdings LLC [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Business Combination, Integration Related Costs				(4,000,000)				$ 1,000,000	23,000,000	$ 2,000,000
Goodwill, Acquired During Period				8,000,000		$ 4,016,000,000
Pepco Holdings LLC [Member] | Successor [Member]
Business Acquisition [Line Items]
Revenues				1,066,000,000	1,171,000,000
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Business Combination, Integration Related Costs	$ 55,000,000			(1,000,000)
Investments				131,000,000	131,000,000				131,000,000
Other noncurrent assets				57,000,000	57,000,000				57,000,000
Business Combination, Contingent Consideration, Asset				251,000,000	251,000,000				251,000,000		$ (235,000,000)
Net income				52,000,000	(257,000,000)
Members' Capital				8,028,000,000	8,028,000,000				8,028,000,000		$ 7,200,000,000
Pepco Holdings LLC [Member] | Pepco Holdings LLC [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Other Commitment				363,000,000	363,000,000				363,000,000
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
Total assets held for sale				$ 61,000,000	$ 61,000,000				$ 61,000,000
Subsequent Event [Member] | ConEdision [Member]
Payments to Acquire Businesses and Interest in Affiliates [Abstract]
Payments to Acquire Businesses, Gross			(53,000,000)
Net Working Capital			$ 130,000,000
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 - Assets Disposition Table (Details) - USD ($)	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Assets Disposition Table [Line Items]
Payments to Acquire Businesses, Gross	$ 6,642,000,000	$ 28,000,000
Other current liabilities	1,025,000,000		$ 842,000,000
Pepco Holdings [Member]
Assets Disposition Table [Line Items]
Payments to Acquire Businesses, Gross	7,142,000,000
Potomac Electric Power Company [Member]
Assets Disposition Table [Line Items]
Gain (Loss) on Disposition of Property Plant Equipment	8,000,000
Other current liabilities	$ 13,000,000		$ 25,000,000

Mergers, Acquisitions, and Di53

Mergers, Acquisitions, and Dispositions Merger Commitments Table (Details)	Jun. 30, 2016USD ($)
Other Commitments [Line Items]
Other Commitment	$ 6,399,000,000
Potomac Electric Power Company [Member]
Other Commitments [Line Items]
Other Commitment	14,000,000
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	508,000,000
Pepco Holdings LLC [Member] | Pepco Holdings LLC [Member]
Other Commitments [Line Items]
Other Commitment	363,000,000
Pepco Holdings LLC [Member] | Potomac Electric Power Company [Member]
Other Commitments [Line Items]
Other Commitment	139,000,000
Pepco Holdings LLC [Member] | Delmarva Power and Light Company [Member]
Other Commitments [Line Items]
Other Commitment	104,000,000
Pepco Holdings LLC [Member] | Atlantic City Electric Company [Member]
Other Commitments [Line Items]
Other Commitment	120,000,000
Pepco Holdings LLC [Member] | Rate Bill Credits [Member]
Other Commitments [Line Items]
Other Commitment	185,000,000
Pepco Holdings LLC [Member] | Rate Bill Credits [Member] | Pepco Holdings LLC [Member]
Other Commitments [Line Items]
Other Commitment	185,000,000
Pepco Holdings LLC [Member] | Rate Bill Credits [Member] | Potomac Electric Power Company [Member]
Other Commitments [Line Items]
Other Commitment	65,000,000
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	62,000,000
Pepco Holdings LLC [Member] | Energy Efficiency Program [Member]
Other Commitments [Line Items]
Other Commitment	64,000,000
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	11,000,000
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] | Most Favored Nation [Member]
Other Commitments [Line Items]
Other Commitment	129,000,000
Pepco Holdings LLC [Member] | Most Favored Nation [Member] | Pepco Holdings LLC [Member]
Other Commitments [Line Items]
Other Commitment	99,000,000
Pepco Holdings LLC [Member] | Most Favored Nation [Member] | Potomac Electric Power Company [Member]
Other Commitments [Line Items]
Other Commitment	19,000,000
Pepco Holdings LLC [Member] | Most Favored Nation [Member] | Delmarva Power and Light Company [Member]
Other Commitments [Line Items]
Other Commitment	32,000,000
Pepco Holdings LLC [Member] | Most Favored Nation [Member] | Atlantic City Electric Company [Member]
Other Commitments [Line Items]
Other Commitment	48,000,000
Pepco Holdings LLC [Member] | Customer Base Rate Credit [Member]
Other Commitments [Line Items]
Other Commitment	26,000,000
Pepco Holdings LLC [Member] | Customer Base Rate Credit [Member] | Pepco Holdings LLC [Member]
Other Commitments [Line Items]
Other Commitment	26,000,000
Pepco Holdings LLC [Member] | Customer Base Rate Credit [Member] | Potomac Electric Power Company [Member]
Other Commitments [Line Items]
Other Commitment	26,000,000
Pepco Holdings LLC [Member] | Customer Base Rate Credit [Member] | Delmarva Power and Light Company [Member]
Other Commitments [Line Items]
Other Commitment	0
Pepco Holdings LLC [Member] | Customer Base Rate Credit [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	7,000,000
Pepco Holdings LLC [Member] | Other1 [Member] | Pepco Holdings LLC [Member]
Other Commitments [Line Items]
Other Commitment	3,000,000
Pepco Holdings LLC [Member] | Other1 [Member] | Potomac Electric Power Company [Member]
Other Commitments [Line Items]
Other Commitment	1,000,000
Pepco Holdings LLC [Member] | Other1 [Member] | Delmarva Power and Light Company [Member]
Other Commitments [Line Items]
Other Commitment	2,000,000
Pepco Holdings LLC [Member] | Other1 [Member] | Atlantic City Electric Company [Member]
Other Commitments [Line Items]
Other Commitment	$ 0

Mergers, Acquisitions, and Di54

Mergers, Acquisitions, and Dispositions Merger Transaction Table (Details) - USD ($) $ / shares in Units, shares in Thousands	3 Months Ended	6 Months Ended
	Mar. 23, 2016	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Business Acquisition, Share Price		$ 27.25
Investments		$ 502,000,000		$ 639,000,000
Shares, Issued		957,616		954,668
Payments to Acquire Businesses, Gross		$ 6,642,000,000	$ 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

Mergers, Acquisitions, and Di55

Mergers, Acquisitions, and Dispositions Purchase Price Allocation Table (Details) $ in Millions	Jun. 30, 2016USD ($)
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	11,076
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	21,804
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities	2,763
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	14,662
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	4,024
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent	3,443
_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRetirmentObligations	821
Scenario, Adjustment [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, Noncurrent Assets	249
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities	2,764
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	5,661
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other	187
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent	3,448
Potomac Electric Power Company [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets	1,691
Delmarva Power and Light Company [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets	$ 1,174

Mergers, Acquisitions, and Di56

Mergers, Acquisitions, and Dispositions Goodwill Amortization Schedule (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Goodwill [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets	$ 4,024
Goodwill, Gross	6,696		$ 2,672
Goodwill, Acquired During Period	8	$ 4,016
Atlantic City Electric Company [Member]
Goodwill [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets	1,098
Pepco Holdings LLC [Member]
Goodwill [Line Items]
Goodwill, Gross	4,024
Goodwill, Acquired During Period	$ 8	$ 4,016

Mergers, Acquisitions, and Di57

Mergers, Acquisitions, and Dispositions ProForma Impact of Merger (Details) - USD ($) $ / shares in Thousands, $ in Millions		3 Months Ended		6 Months Ended		12 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Business Acquisition, Pro Forma Revenue		$ 6,910	$ 7,522	$ 15,466	$ 17,584	$ 33,823
Business Acquisition, Pro Forma Net Income (Loss)		$ 268	$ 623	$ 845	$ 1,423	$ 2,618
Business Acquisition, Pro Forma Earnings Per Share, Basic		$ 0	$ 0	$ 0	$ 0	$ 0
Business Acquisition, Pro Forma Earnings Per Share, Diluted		$ 0	$ 0	$ 0	$ 0	$ 0
Noncash Merger Related Costs	[1],[2]			$ 503
Consolidation, Eliminations [Member]
Business Acquisition, Pro Forma Revenue	[3]		$ 111	170	$ 233	$ 559
Noncash Merger Related Costs	[3]	$ 1	$ (82)	$ 641	$ 35	$ 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 $1 million and $641 million for the three and six months ended June 30, 2016, respectively, and intercompany revenue of $170 million for the six months ended June 30, 2016.

Mergers, Acquisitions, and Di58

Mergers, Acquisitions, and Dispositions Merger Integration Related Costs Table (Details) - USD ($) $ in Millions	Mar. 31, 2016	Jun. 30, 2016	Mar. 23, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Business Combination, Integration Related Costs		$ 1		$ (87)	$ 103	$ 21
Exelon Generation Co L L C [Member]
Business Combination, Integration Related Costs		4		7	20	15
Commonwealth Edison Co [Member]
Business Combination, Integration Related Costs		1		3	(7)	6
PECO Energy Co [Member]
Business Combination, Integration Related Costs		1		1	2	2
Baltimore Gas and Electric Company [Member]
Business Combination, Integration Related Costs		(5)		1	(4)	3
Pepco Holdings LLC [Member]
Business Combination, Integration Related Costs		(4)		1	23	2
Delmarva Power and Light Company [Member]
Business Combination, Integration Related Costs		0		1	16	1
Atlantic City Electric Company [Member]
Business Combination, Integration Related Costs		2		1	15	1
Successor [Member] | Pepco Holdings LLC [Member]
Business Combination, Integration Related Costs	$ 55	$ (1)
Predecessor [Member] | Pepco Holdings LLC [Member]
Business Combination, Integration Related Costs			$ 29	$ 5		$ 14
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					12
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 ($)	Apr. 30, 2012MW	Aug. 31, 2014USD ($)	May 31, 2014USD ($)	Mar. 31, 2013USD ($)	Jun. 30, 2016USD ($)		Jun. 30, 2015USD ($)	Jun. 30, 2016USD ($)		Jun. 30, 2015USD ($)	Dec. 31, 2015USD ($)		Jul. 31, 2014USD ($)	Aug. 31, 2010USD ($)
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets							$ 11,680,000,000			$ 11,680,000,000			$ 6,824,000,000
Business Combination, Integration Related Costs							1,000,000		$ (87,000,000)	103,000,000		$ 21,000,000
Capital Expenditures Incurred but Not yet Paid										(364,000,000)
Regulatory Liabilities							4,892,000,000			4,892,000,000			4,570,000,000
Regulatory assets							10,121,000,000			10,121,000,000			6,065,000,000
Regulatory Liability, Current							503,000,000			503,000,000			369,000,000
Other Commitment							6,399,000,000			6,399,000,000
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							1,136,000,000			1,136,000,000			1,113,000,000
Business Combination, Integration Related Costs							1,000,000		3,000,000	(7,000,000)		$ 6,000,000
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount										94,000,000
Capital Expenditures Incurred but Not yet Paid										(21,000,000)
Regulatory Liabilities							3,677,000,000			3,677,000,000			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							923,000,000			$ 923,000,000			895,000,000
Regulatory Liability, Current							153,000,000			153,000,000			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							1,684,000,000			1,684,000,000			1,617,000,000
Business Combination, Integration Related Costs							1,000,000		1,000,000	2,000,000		$ 2,000,000
Capital Expenditures Incurred but Not yet Paid										(12,000,000)
Regulatory Liabilities							657,000,000			657,000,000			639,000,000
Regulatory assets							1,636,000,000			1,636,000,000			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							781,000,000			781,000,000			781,000,000
Business Combination, Integration Related Costs							(5,000,000)		1,000,000	(4,000,000)		3,000,000
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount										15,000,000
Customer Refund Liability, Noncurrent							30,000,000			30,000,000
Capital Expenditures Incurred but Not yet Paid										2,000,000
Regulatory Liabilities							197,000,000			197,000,000			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							520,000,000			520,000,000			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							60,000,000			$ 60,000,000			38,000,000
Other Commitment							262,000,000			262,000,000
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
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
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							4,000,000		7,000,000	20,000,000		15,000,000
Unregulated Operating Revenue										101,000,000
Customer Refund Liability, Noncurrent							20,000,000			20,000,000
Capital Expenditures Incurred but Not yet Paid										(317,000,000)
Customer Refund							20,000,000			20,000,000
License Costs										26,000,000
Other Commitment							5,589,000,000			5,589,000,000					$ 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
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										11,000,000
Regulatory Liabilities							$ 51,000,000			51,000,000			44,000,000
Public Utilities, Requested Rate Increase (Decrease), Amount										2,000,000
Approved ROE							10.60%
Regulatory assets							$ 669,000,000			$ 669,000,000			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							27,000,000			$ 27,000,000			15,000,000
Other Commitment							14,000,000			14,000,000
Projected Capital Expenditures					$ 1,000,000,000
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), 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							358,000,000			358,000,000			371,000,000
Business Combination, Integration Related Costs							0		1,000,000	16,000,000		1,000,000
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount										(14,000,000)
Capital Expenditures Incurred but Not yet Paid										(9,000,000)
Regulatory Liabilities							155,000,000			155,000,000			160,000,000
Public Utilities, Requested Rate Increase (Decrease), Amount							62,800,000			$ 8,000,000
Public Utilities, Approved Rate Increase (Decrease), Amount				$ 15,000,000
Requested Debt and Equity Return on Distribution										10.60%
Public Utilities, Interim Rate Increase (Decrease), Amount										$ 2,500,000
Approved ROE				9.70%
ICC Approved Rate Increase (Decrease), Amount				$ 15,000,000
Regulatory assets							295,000,000			$ 295,000,000			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							53,000,000			$ 53,000,000			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), Amount						$ 42,000,000				66,000,000
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							515,000,000			515,000,000			512,000,000
Business Combination, Integration Related Costs							2,000,000		$ 1,000,000	15,000,000		$ 1,000,000
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount										(6,000,000)
Capital Expenditures Incurred but Not yet Paid										6,000,000
Regulatory Liabilities							23,000,000			23,000,000			25,000,000
Public Utilities, Requested Rate Increase (Decrease), Amount										8,000,000
Public Utilities, Interim Rate Increase (Decrease), Amount							9,000,000			19,000,000
Regulatory assets							418,000,000			$ 418,000,000			414,000,000
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							21,000,000			$ 21,000,000			18,000,000
Other Commitment							9,000,000			9,000,000
Current Year Revenue Adjustment										0
Proposed Capital Expenditure										$ 176,000,000
Requested ROE										10.60%
Atlantic City Electric Company [Member] | Electric Distribution [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount										$ 85,000,000
Under Recovered Energy And Transmission Costs [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets							103,000,000			103,000,000			84,000,000
Under Recovered Energy And Transmission Costs [Member] | Commonwealth Edison Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets	[1]						41,000,000			41,000,000			43,000,000
Business Combination, Integration Related Costs										7,000,000			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]						36,000,000			36,000,000			40,000,000
Under Recovered Energy And Transmission Costs [Member] | Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets							0			0			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]						6,000,000			6,000,000			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]						20,000,000			20,000,000			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
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]						11,000,000			11,000,000			6,000,000
Merger Integration Costs [Member] | Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets							9,000,000	[8]		9,000,000	[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							207,000,000			207,000,000			189,000,000
Under Recovered Distribution Service Costs [Member] | Commonwealth Edison Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets	[10]						207,000,000			207,000,000			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] | Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets							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
Under Recovered Distribution Service Costs [Member] | Atlantic City Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets							0			0
AMI Expenses [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets							712,000,000			712,000,000			399,000,000
AMI Expenses [Member] | Commonwealth Edison Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets													140,000,000
AMI Expenses [Member] | PECO Energy Co [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets													63,000,000
AMI Expenses [Member] | Baltimore Gas and Electric Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets	[11]												196,000,000
Regulatory assets							240,000,000			240,000,000			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] | Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets							174,000,000	[11]		174,000,000	[11]		180,000,000
AMI Expenses [Member] | Delmarva Power and Light Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets							86,000,000	[11]		86,000,000	[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							634,000,000			634,000,000			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							264,000,000			264,000,000			278,000,000
Energy Efficiency And Demand Response Programs [Member] | Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets							266,000,000			266,000,000			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							103,000,000			103,000,000			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							56,000,000			56,000,000
Legacy AMI [Member] | Potomac Electric Power Company [Member]
Regulatory Matters Additional Narrative Information [Line Items]
Regulatory Assets							78,000,000			78,000,000
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 June 30, 2016, ComEd’s regulatory asset of $41 million included $4 million related to under-recovered energy costs, $30 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 June 30, 2016, ComEd’s regulatory liability of $41 million included $13 million related to over-recovered energy costs and $28 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 June 30, 2016, PECO's regulatory liability of $63 million included $31 million related to over-recovered costs under the DSP program, $23 million related to the over-recovered natural gas costs under the PGC, $7 million related to over-recovered non-bypassable transmission service charges and$2 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 June 30, 2016, BGE's regulatory asset of $36 million included $6 million of costs associated with transmission costs recoverable through its FERC approved formula rate, $29 million related to under-recovered electric energy costs, and $1 million of abandonment costs to be recovered upon FERC approval. As of June 30, 2016, BGE's regulatory liability of $8 million related to $8 million of over-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 June 30, 2016, Pepco's regulatory liability of $22 million included $12 million of over-recovered transmission costs and $10 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 June 30, 2016, DPL's regulatory asset of $6 million related to under-recovered electric energy costs. As of June 30, 2016, DPL's regulatory liability of $21 million included $4 million related to over-recovered natural gas costs under the GCR mechanism, $10 million of over-recovered electric energy costs, and $7 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 June 30, 2016, ACE's regulatory asset of $20 million related to of under-recovered electric energy costs. As of June 30, 2016, ACE's regulatory liability of $9 million related to over-recovered transmission 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 June 30, 2016, BGE's regulatory asset of $11 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 June 30, 2016, ComEd’s regulatory asset of $207 million was comprised of $163 million for the 2014 - 2016 annual reconciliations and $44 million related to significant one-time events including $28 million of deferred storm costs, $11 million of Constellation and PHI merger and integration related costs and $5 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]	$139 million for Pepco and $43 million for DPL, of which $78 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			6 Months Ended			12 Months Ended
		Jun. 30, 2016		Jun. 30, 2015	Jun. 30, 2016		Jun. 30, 2015	Dec. 31, 2015
Regulatory Assets [Line Items]
Current		$ 1,559			$ 1,559			$ 759
Noncurrent		10,121			10,121			6,065
Regulatory Assets		11,680			11,680			6,824
Regulatory Liabilities		4,892			4,892			4,570
Business Combination, Integration Related Costs		1		$ (87)	103		$ 21
Other Postretirement Benefits [Member]
Regulatory Assets [Line Items]
Regulatory Assets		4,160	[1]		4,160	[1]		3,156
Deferred Income Tax Charge [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1,928			1,928			1,616
AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets		712			712			399
Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		207			207			189
Loss on Reacquired Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		130			130			47
Fair Value Of Long Term Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		847			847			162	[2]
Fair Value Of Supply Contract [Member]
Regulatory Assets [Line Items]
Current		1,350			1,350
Employee Severance [Member]
Regulatory Assets [Line Items]
Regulatory Assets		7			7			9
Asset Retirement Obligation Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		117			117			108
Environmental Restoration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		290			290			286
Under Recovered Uncollectible Accounts Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets		54			54			52
Renewable Energy And Associated REC [Member]
Regulatory Assets [Line Items]
Regulatory Assets		226			226			247
Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		103			103			84
Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		43			43			2
Electric Generation Related Regulatory Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets		15			15			20
Rate Stabilization Deferral [Member]
Regulatory Assets [Line Items]
Regulatory Assets		54			54			87
Energy Efficiency And Demand Response Programs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		634			634			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		44			44			29
Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Current		40			40
Regulatory Assets								30
Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		10			10			0
Workers Compensation and Long-Term Disability [Member]
Regulatory Assets [Line Items]
Regulatory Assets		31			31			0
Recoverable Vacation Pay [Member]
Regulatory Assets [Line Items]
Regulatory Assets		47			47			6
Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		169			169			0
CAP Arrearage [Member]
Regulatory Assets [Line Items]
Regulatory Assets		7			7			7
AssetRemovalCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets		425			425
Under funded Benefit Post Retirement Obligation [Member]
Regulatory Assets [Line Items]
Regulatory Assets		1,087			1,087
Alternative Energy Credits [Member]
Regulatory Assets [Line Items]
Regulatory Assets		7			7
Commonwealth Edison Co [Member]
Regulatory Assets [Line Items]
Current		213			213			218
Noncurrent		923			923			895
Regulatory Assets		1,136			1,136			1,113
Regulatory Liabilities		3,677			3,677			3,614
Business Combination, Integration Related Costs		1		3	(7)		6
Commonwealth Edison Co [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets		19			19			15
Commonwealth Edison Co [Member] | TransmissionCost [Member]
Regulatory Assets [Line Items]
Regulatory Assets		30			30
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		70	[3]		70	[3]		64
Commonwealth Edison Co [Member] | Recoverable Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		44			44			47
Commonwealth Edison Co [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets								140
Commonwealth Edison Co [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[4]	207			207			189
Business Combination, Integration Related Costs					11			11
Commonwealth Edison Co [Member] | Loss on Reacquired Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		44			44			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		262			262			255
Commonwealth Edison Co [Member] | Under Recovered Uncollectible Accounts Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets		54			54			52
Commonwealth Edison Co [Member] | Renewable Energy And Associated REC [Member]
Regulatory Assets [Line Items]
Regulatory Assets		221			221			247
Commonwealth Edison Co [Member] | Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[5]	41			41			43
Business Combination, Integration Related Costs					7			7
Commonwealth Edison Co [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		28			28			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
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		7			7			10
Business Combination, Integration Related Costs					8
Commonwealth Edison Co [Member] | Advanced Metering Infrastructure Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		5			5
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		163			163			142
Commonwealth Edison Co [Member] | Under-Recovered Electric Supply Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		4			4			5
Commonwealth Edison Co [Member] | ElectricTransmissionCostsUnderRecovery [Member]
Regulatory Assets [Line Items]
Regulatory Assets								31
Commonwealth Edison Co [Member] | Recoverable Smart Meter Related Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		156			156
PECO Energy Co [Member]
Regulatory Assets [Line Items]
Current		48			48			34
Noncurrent		1,636			1,636			1,583
Regulatory Assets		1,684			1,684			1,617
Regulatory Liabilities		657			657			639
Business Combination, Integration Related Costs		1		1	2		2
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		1,536			1,536			1,473
PECO Energy Co [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets								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		13			13			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		21			21			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
PECO Energy Co [Member] | Recoverable Smart Meter Related Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		56			56
Baltimore Gas and Electric Company [Member]
Regulatory Assets [Line Items]
Current		261			261			267
Noncurrent		520			520			514
Regulatory Assets		781			781			781
Regulatory Liabilities		197			197			222
Business Combination, Integration Related Costs		(5)		1	(4)		3
Baltimore Gas and Electric Company [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets		30			30			16
Baltimore Gas and Electric Company [Member] | TransmissionCost [Member]
Regulatory Assets [Line Items]
Regulatory Assets		6			6			12
Baltimore Gas and Electric Company [Member] | UnderRecoveredElectricEnergyCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets		29			29			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		240			240			196
Regulatory Assets	[7]							196
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		7			7			9
Baltimore Gas and Electric Company [Member] | Asset Retirement Obligation Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		20			20			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]	36			36			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		15			15			20
Baltimore Gas and Electric Company [Member] | Rate Stabilization Deferral [Member]
Regulatory Assets [Line Items]
Regulatory Assets		54			54			87
Baltimore Gas and Electric Company [Member] | Energy Efficiency And Demand Response Programs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		264			264			278
Baltimore Gas and Electric Company [Member] | Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[9]	11			11			6
Baltimore Gas and Electric Company [Member] | Merger Integration Costs [Member] | Pepco Holdings [Member]
Regulatory Assets [Line Items]
Regulatory Assets		6			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]
Current	[10]	26			26
Regulatory Assets	[10]							30
Baltimore Gas and Electric Company [Member] | Under-Recovered Electric Revenue Decoupling [Member]
Regulatory Assets [Line Items]
Regulatory Assets								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] | Recoverable Smart Meter Related Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		240			240
Baltimore Gas and Electric Company [Member] | Legacy AMI [Member]
Regulatory Assets [Line Items]
Regulatory Assets		56			56
Baltimore Gas and Electric Company [Member] | AMI Post Test Year [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		730			730
Noncurrent		3,044			3,044
Regulatory Assets		3,774			3,774
Regulatory Liabilities		272			272
PEPCO Holdings Inc [Member] | TransmissionCost [Member]
Regulatory Assets [Line Items]
Regulatory Assets								5
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		228			228
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		260			260
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]	85			85
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]	698			698
PEPCO Holdings Inc [Member] | Fair Value Of Supply Contract [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[12]	1,350			1,350
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		5			5
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		26			26
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		42			42
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		369			369
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		12			12
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		16			16
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		14			14
PEPCO Holdings Inc [Member] | Deferred Project Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		10			10
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		31			31
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		26			26
PEPCO Holdings Inc [Member] | Abandonment costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets								4
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		169			169
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		425			425
PEPCO Holdings Inc [Member] | Alternative Energy Credits [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[13]	7			7
Potomac Electric Power Company [Member]
Regulatory Assets [Line Items]
Current		129			129			140
Noncurrent		669			669			661
Regulatory Assets		798			798			801
Regulatory Liabilities		51			51			44
Potomac Electric Power Company [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets		38			38			36
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		148	[3]		148	[3]		137
Potomac Electric Power Company [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets		174	[7]		174	[7]		180
Potomac Electric Power Company [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		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		0			0			9	[14]
Potomac Electric Power Company [Member] | Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		17			17			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		266			266			289
Potomac Electric Power Company [Member] | Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		9	[15]		9	[15]		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		10			10			14
Business Combination, Integration Related Costs					9
Potomac Electric Power Company [Member] | Under Recovered Decoupling Revenue [Member]
Regulatory Assets [Line Items]
Current		12			12
Regulatory Assets								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		31			31			31
Potomac Electric Power Company [Member] | Recoverable Vacation Pay [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0			0
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		112			112			92
Potomac Electric Power Company [Member] | Recoverable Smart Meter Related Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		139			139
Potomac Electric Power Company [Member] | Legacy AMI [Member]
Regulatory Assets [Line Items]
Regulatory Assets		78			78
Potomac Electric Power Company [Member] | AMI Post Test Year [Member]
Regulatory Assets [Line Items]
Regulatory Assets		2			2
Delmarva Power and Light Company [Member]
Regulatory Assets [Line Items]
Current		63			63			72
Noncurrent		295			295			299
Regulatory Assets		358			358			371
Regulatory Liabilities		155			155			160
Business Combination, Integration Related Costs		0		1	16		1
Delmarva Power and Light Company [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets		19			19			18
Delmarva Power and Light Company [Member] | TransmissionCost [Member]
Regulatory Assets [Line Items]
Regulatory Assets								7
Delmarva Power and Light Company [Member] | UnderRecoveredElectricEnergyCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets								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		36	[3]		36	[3]		36
Delmarva Power and Light Company [Member] | AMI Expenses [Member]
Regulatory Assets [Line Items]
Regulatory Assets		86	[7]		86	[7]		87
Delmarva Power and Light Company [Member] | Under Recovered Distribution Service Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		0			0
Delmarva Power and Light Company [Member] | Loss on Reacquired Debt [Member]
Regulatory Assets [Line Items]
Regulatory Assets		10			10			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		1			1			1
Delmarva Power and Light Company [Member] | Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[16]	6			6			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		103			103			111
Delmarva Power and Light Company [Member] | Merger Integration Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		3	[17]		3	[17]		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		3			3			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		10			10			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		15			15			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		78			78			69
Delmarva Power and Light Company [Member] | Recoverable Smart Meter Related Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		43			43
Delmarva Power and Light Company [Member] | Legacy AMI [Member]
Regulatory Assets [Line Items]
Regulatory Assets		14			14
Atlantic City Electric Company [Member]
Regulatory Assets [Line Items]
Current		97			97			98
Noncurrent		418			418			414
Regulatory Assets		515			515			512
Regulatory Liabilities		23			23			25
Business Combination, Integration Related Costs		2		$ 1	15		$ 1
Atlantic City Electric Company [Member] | Deferred Income Tax Transmission Related [Member]
Regulatory Assets [Line Items]
Regulatory Assets		17			17			15
Atlantic City Electric Company [Member] | TransmissionCost [Member]
Regulatory Assets [Line Items]
Regulatory Assets								2
Atlantic City Electric Company [Member] | UnderRecoveredElectricEnergyCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets		20			20			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		44	[3]		44	[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
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		4			4			5
Atlantic City Electric Company [Member] | Under Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	[18]	20			20			13
Atlantic City Electric Company [Member] | Deferred Storm Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		20			20			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		11			11			9
Atlantic City Electric Company [Member] | Stranded Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets		169			169			202
Atlantic City Electric Company [Member] | AssetRemovalCosts [Member]
Regulatory Assets [Line Items]
Regulatory Assets		236			236			208
Renewable energy Requirements [Member] | Commonwealth Edison Co [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		28			28			24
Over Recovered Transmission Costs [Member] | PECO Energy Co [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		2			2			3
Over Recovered Transmission Costs [Member] | Baltimore Gas and Electric Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities								14
Over Recovered Transmission Costs [Member] | Potomac Electric Power Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		12			12			14
Over Recovered Transmission Costs [Member] | Delmarva Power and Light Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		7			7			11
Over Recovered Energy And Transmission Costs [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		164			164			131
Over Recovered Energy And Transmission Costs [Member] | Commonwealth Edison Co [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities	[5]	41			41			53
Over Recovered Energy And Transmission Costs [Member] | PECO Energy Co [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities	[6]	63			63			60
Over Recovered Energy And Transmission Costs [Member] | Baltimore Gas and Electric Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities	[8]	8			8			18
Over Recovered Energy And Transmission Costs [Member] | PEPCO Holdings Inc [Member] | Predecessor [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities								27
Over Recovered Energy And Transmission Costs [Member] | PEPCO Holdings Inc [Member] | Successor [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		52			52
Over Recovered Energy And Transmission Costs [Member] | Potomac Electric Power Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities	[14]	22			22			16
Over Recovered Energy And Transmission Costs [Member] | Delmarva Power and Light Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities	[16]	21			21			19
Over Recovered Energy And Transmission Costs [Member] | Atlantic City Electric Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities	[18]	9			9			8
Over Recovered Electric Supply Cost [Member] | Commonwealth Edison Co [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities								29
Over Recovered Electric Supply Cost [Member] | Potomac Electric Power Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		10			10			2
Over Recovered Electric Supply Cost [Member] | Delmarva Power and Light Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		10			10			4
Over-Recovered Natural Gas Costs [Member] | PECO Energy Co [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		23			23			22
Over-Recovered Natural Gas Costs [Member] | Baltimore Gas and Electric Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		8			8			5
Over-Recovered Natural Gas Costs [Member] | Delmarva Power and Light Company [Member]
Regulatory Assets [Line Items]
Regulatory Liabilities		$ 4			$ 4			$ 4
[1]	As of June 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 June 30, 2016, includes transmission-related regulatory assets that require FERC approval separate from the transmission formula rate of $19 million, $30 million, $38 million, $19 million and $17 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 June 30, 2016, ComEd’s regulatory asset of $207 million was comprised of $163 million for the 2014 - 2016 annual reconciliations and $44 million related to significant one-time events including $28 million of deferred storm costs, $11 million of Constellation and PHI merger and integration related costs and $5 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 June 30, 2016, ComEd’s regulatory asset of $41 million included $4 million related to under-recovered energy costs, $30 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 June 30, 2016, ComEd’s regulatory liability of $41 million included $13 million related to over-recovered energy costs and $28 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 June 30, 2016, PECO's regulatory liability of $63 million included $31 million related to over-recovered costs under the DSP program, $23 million related to the over-recovered natural gas costs under the PGC, $7 million related to over-recovered non-bypassable transmission service charges and$2 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]	$139 million for Pepco and $43 million for DPL, of which $78 million for Pepco and $14 million for DPL relates to retired legacy meters which are not earning a return
[8]	As of June 30, 2016, BGE's regulatory asset of $36 million included $6 million of costs associated with transmission costs recoverable through its FERC approved formula rate, $29 million related to under-recovered electric energy costs, and $1 million of abandonment costs to be recovered upon FERC approval. As of June 30, 2016, BGE's regulatory liability of $8 million related to $8 million of over-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 June 30, 2016, BGE's regulatory asset of $11 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 June 30, 2016, BGE had a regulatory asset of $26 million related to under-recovered electric revenue decoupling and a regulatory liability of $3 million related to over-recovered natural gas 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]	Represents the electric and natural gas distribution costs recoverable from customers under BGE’s decoupling mechanism. As of June 30, 2016, BGE had a regulatory asset of $26 million related to under-recovered electric revenue decoupling and a regulatory liability of $3 million related to over-recovered natural gas 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.
[14]	As of June 30, 2016, Pepco's regulatory liability of $22 million included $12 million of over-recovered transmission costs and $10 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.
[15]	epresents previously incurred PHI acquisition costs expected to be recovered in distribution rates
[16]	As of June 30, 2016, DPL's regulatory asset of $6 million related to under-recovered electric energy costs. As of June 30, 2016, DPL's regulatory liability of $21 million included $4 million related to over-recovered natural gas costs under the GCR mechanism, $10 million of over-recovered electric energy costs, and $7 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.
[17]	.
[18]	As of June 30, 2016, ACE's regulatory asset of $20 million related to of under-recovered electric energy costs. As of June 30, 2016, ACE's regulatory liability of $9 million related to over-recovered transmission 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 - Schedule of Regulatory Liabilities (Details) - USD ($) $ in Millions		Jun. 30, 2016	Dec. 31, 2015
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		$ 503	$ 369
Noncurrent		4,389	4,201
Regulatory Liabilities		4,892	4,570
Regulatory Assets		11,680	6,824
Electric Transmission And Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		84	95
Other Postretirement Benefits [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		90	94
Nuclear Decommissioning [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		2,642	2,577
Removal Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		1,648	1,527
Deferred Lease Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		42
Energy Efficiency Demand Response Programs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		134	92
Dlc Program Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		9	9
Gas Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		24	28
Over Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		164	131
Over Recovered Decoupling Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		3	1
Regulatory Liabilities Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		52	16
Baltimore Gas and Electric Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		60	38
Noncurrent		137	184
Regulatory Liabilities		197	222
Regulatory Assets		781	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		1	1
Baltimore Gas and Electric Company [Member] | Over Recovered Decoupling Gas Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		3	1
Baltimore Gas and Electric Company [Member] | Over Recovered Decoupling Electric Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		26
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		172	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]	8	18
Baltimore Gas and Electric Company [Member] | Over Recovered Decoupling Revenue [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[2]	3	1
Baltimore Gas and Electric Company [Member] | Regulatory Liabilities Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		14	8
Baltimore Gas and Electric Company [Member] | Over-Recovered Natural Gas Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		8	5
PECO Energy Co [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		128	112
Noncurrent		529	527
Regulatory Liabilities		657	639
Regulatory Assets		1,684	1,617
PECO Energy Co [Member] | Over Recovered NonBypassable Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		7
PECO Energy Co [Member] | Over Recovered Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		2	3
PECO Energy Co [Member] | Electric Transmission And Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		84	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		437	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		37	40
PECO Energy Co [Member] | Dlc Program Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		9	9
PECO Energy Co [Member] | Gas Distribution Tax Repairs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		24	28
PECO Energy Co [Member] | Over Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[3]	63	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		3	2
PECO Energy Co [Member] | Over-Recovered Natural Gas Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		23	22
PECO Energy Co [Member] | Default Service Provider Program [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		31	35
Commonwealth Edison Co [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		153	155
Noncurrent		3,524	3,459
Regulatory Liabilities		3,677	3,614
Regulatory Assets		1,136	1,113
Commonwealth Edison Co [Member] | Over Recovered Energy Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		13
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		2,205	2,172
Commonwealth Edison Co [Member] | Removal Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		1,330	1,332
Commonwealth Edison Co [Member] | Energy Efficiency Demand Response Programs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		97	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]	41	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		4	5
Commonwealth Edison Co [Member] | Renewable energy Requirements [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		28	24
Commonwealth Edison Co [Member] | Over Recovered Electric Supply Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities			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		171
Regulatory Liabilities		272
Regulatory Assets		3,774
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		146
PEPCO Holdings Inc [Member] | Deferred Lease Revenue [Member] | Successor [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities	[5]	42
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		52
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		32
Potomac Electric Power Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		27	15
Noncurrent		24	29
Regulatory Liabilities		51	44
Regulatory Assets		798	801
Potomac Electric Power Company [Member] | Over Recovered Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		12	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]	22	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		9	7
Potomac Electric Power Company [Member] | Over Recovered Electric Supply Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		10	2
Delmarva Power and Light Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		53	49
Noncurrent		102	111
Regulatory Liabilities		155	160
Regulatory Assets		358	371
Delmarva Power and Light Company [Member] | Over Recovered Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		7	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		126	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]	21	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		8	12
Delmarva Power and Light Company [Member] | Over-Recovered Natural Gas Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		4	4
Delmarva Power and Light Company [Member] | Over Recovered Electric Supply Cost [Member]
Regulatory Liabilities [Line Items]
Regulatory Liabilities		10	4
Atlantic City Electric Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current		21	18
Noncurrent		2	7
Regulatory Liabilities		23	25
Regulatory Assets		515	512
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]	9	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		14	16
Under Recovered Energy And Transmission Costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets		103	84
Under Recovered Energy And Transmission Costs [Member] | Baltimore Gas and Electric Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets	[1]	36	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]	41	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		26
Under Recovered Energy And Transmission Costs [Member] | Potomac Electric Power Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets		0	9	[6]
Under Recovered Energy And Transmission Costs [Member] | Delmarva Power and Light Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets	[7]	6	11
Under Recovered Energy And Transmission Costs [Member] | Atlantic City Electric Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Assets	[8]	$ 20	$ 13
[1]	As of June 30, 2016, BGE's regulatory asset of $36 million included $6 million of costs associated with transmission costs recoverable through its FERC approved formula rate, $29 million related to under-recovered electric energy costs, and $1 million of abandonment costs to be recovered upon FERC approval. As of June 30, 2016, BGE's regulatory liability of $8 million related to $8 million of over-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 June 30, 2016, BGE had a regulatory asset of $26 million related to under-recovered electric revenue decoupling and a regulatory liability of $3 million related to over-recovered natural gas 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 June 30, 2016, PECO's regulatory liability of $63 million included $31 million related to over-recovered costs under the DSP program, $23 million related to the over-recovered natural gas costs under the PGC, $7 million related to over-recovered non-bypassable transmission service charges and$2 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 June 30, 2016, ComEd’s regulatory asset of $41 million included $4 million related to under-recovered energy costs, $30 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 June 30, 2016, ComEd’s regulatory liability of $41 million included $13 million related to over-recovered energy costs and $28 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 June 30, 2016, Pepco's regulatory liability of $22 million included $12 million of over-recovered transmission costs and $10 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 June 30, 2016, DPL's regulatory asset of $6 million related to under-recovered electric energy costs. As of June 30, 2016, DPL's regulatory liability of $21 million included $4 million related to over-recovered natural gas costs under the GCR mechanism, $10 million of over-recovered electric energy costs, and $7 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 June 30, 2016, ACE's regulatory asset of $20 million related to of under-recovered electric energy costs. As of June 30, 2016, ACE's regulatory liability of $9 million related to over-recovered transmission 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 Regulatory62

Regulatory Matters Regulatory Matters - Purchase of Receivables Programs (Details) - USD ($) $ in Millions		6 Months Ended		12 Months Ended
		Jun. 30, 2016		Dec. 31, 2015
Purchase Of Receivables [Line Items]
Payments to Acquire Other Receivables		$ 327		$ 229
Allowance for Doubtful Accounts Receivable		31	[1]	31
Payments to Acquire Other Receivables, Net		$ 296		198
Discount rate		1.00%
Commonwealth Edison Co [Member]
Purchase Of Receivables [Line Items]
Payments to Acquire Other Receivables		$ 103		103
Allowance for Doubtful Accounts Receivable		14	[1]	16
Payments to Acquire Other Receivables, Net		89		87
PECO Energy Co [Member]
Purchase Of Receivables [Line Items]
Payments to Acquire Other Receivables		72		67
Allowance for Doubtful Accounts Receivable	[2]	6		7
Payments to Acquire Other Receivables, Net		66		60
Baltimore Gas and Electric Company [Member]
Purchase Of Receivables [Line Items]
Payments to Acquire Other Receivables		54		59
Allowance for Doubtful Accounts Receivable	[1]	5		8
Payments to Acquire Other Receivables, Net		49		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		98
Allowance for Doubtful Accounts Receivable	[1]	6
Payments to Acquire Other Receivables, Net		92
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		69
Allowance for Doubtful Accounts Receivable	[4]	4
Payments to Acquire Other Receivables, Net		65
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		10
Allowance for Doubtful Accounts Receivable	[1]	0
Payments to Acquire Other Receivables, Net		10
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		19
Allowance for Doubtful Accounts Receivable	[1]	2
Payments to Acquire Other Receivables, Net		$ 17
[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 June 30, 2016, BGE's regulatory asset of $36 million included $6 million of costs associated with transmission costs recoverable through its FERC approved formula rate, $29 million related to under-recovered electric energy costs, and $1 million of abandonment costs to be recovered upon FERC approval. As of June 30, 2016, BGE's regulatory liability of $8 million related to $8 million of over-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 Distribution Filings (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	6 Months Ended
	Aug. 31, 2014	Jun. 30, 2016	Jun. 30, 2016	Jun. 30, 2015
Potomac Electric Power Company [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 2
Rate Of Return On Common Equity In Federal Energy Regulatory Committee Complaint			10.50%
Public Utilities, Approved Equity Capital Structure, Percentage			7.88%	8.36%
Delmarva Power and Light Company [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount		$ 62.8	$ 8
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 15
Rate Of Return On Common Equity In Federal Energy Regulatory Committee Complaint			10.50%
Public Utilities, Approved Equity Capital Structure, Percentage			7.21%	7.80%
Atlantic City Electric Company [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 8
Rate Of Return On Common Equity In Federal Energy Regulatory Committee Complaint			10.50%
Public Utilities, Approved Equity Capital Structure, Percentage			7.83%	8.51%
Baltimore Gas and Electric Company [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 12
Rate Of Return On Common Equity In Federal Energy Regulatory Committee Complaint			10.50%
Public Utilities, Approved Equity Capital Structure, Percentage			8.09%	8.46%

Regulatory Matters Annual Ele64

Regulatory Matters Annual Electric Transmission Fillings (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	6 Months Ended
	Aug. 31, 2014	Jun. 30, 2016	Jun. 30, 2016	Jun. 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			$ 15
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
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		62.8	8
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount			$ (14)
Public Utilities, Approved Return on Equity, Percentage	9.70%
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 Asse65

Impairment of Long-Lived Assets (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Mar. 31, 2016
Capital Leases, Net Investment in Direct Financing Leases [Abstract]
Estimated residual value of leased assets	$ 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		$ 60
Constellation Energy Group LLC [Member]
Capital Leases, Net Investment in Direct Financing Leases [Abstract]
Tangible Asset Impairment Charges	119
Disposal Group, Including Discontinued Operation, Assets, Current	$ 61

Early Nuclear Plant Retiremen66

Early Nuclear Plant Retirements Early Nuclear Plant Retirements (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Inventory, Raw Materials and Supplies, Gross	$ 1,183	$ 1,104
Property, plant and equipment, net	70,693	$ 57,439
Ginna [Member]
Property, Plant and Equipment [Line Items]
Inventory, Raw Materials and Supplies, Gross	30
Nuclear Fuel, Net of Amortization	47
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	12
Asset Retirement Obligation	(659)
Property, plant and equipment, net	125
Three Mile Island [Member]
Property, Plant and Equipment [Line Items]
Inventory, Raw Materials and Supplies, Gross	38
Nuclear Fuel, Net of Amortization	104
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	35
Asset Retirement Obligation	(485)
Property, plant and equipment, net	968
Nine Mile Point [Member]
Property, Plant and Equipment [Line Items]
Inventory, Raw Materials and Supplies, Gross	69
Nuclear Fuel, Net of Amortization	235
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	70
Asset Retirement Obligation	(770)
Property, plant and equipment, net	$ 1,137

Early Nuclear Plant Retiremen67

Early Nuclear Plant Retirements Early Nuclear Plant Retirements table (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015
Property, Plant and Equipment [Line Items]
Nuclear Fuel Amortization	[1]	$ 557	$ 552
Asset Retirement Obligation, Accretion Expense	[2]	220	193
Depreciation	[3]	1,432	$ 1,087
Facility Closing [Member]
Property, Plant and Equipment [Line Items]
Other Expenses		$ 110
[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.

Fair Value of Financial Asset68

Fair Value of Financial Assets and Liabilities - Fair Value of Financial Liabilities Recorded at the Carrying Amount (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Spent Nuclear Fuel Obligation, Noncurrent	$ 1,023	$ 1,021
Due to Related Parties, Noncurrent	641	641
Preferred Stock, Value, Issued	193	193
Deferred Finance Costs, Net	200	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	954	536
Long-term debt (including amounts due within one year)(a)	34,234	25,145
Spent Nuclear Fuel Obligation, Noncurrent	1,023	1,021
Due to Related Parties, Noncurrent	641	641
Estimate of Fair Value Measurement [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term Debt, Fair Value	954	536
Long-term debt (including amounts due within one year)(a)	37,174	25,924
Spent Nuclear Fuel Obligation, Noncurrent	835	818
Due to Related Parties, Noncurrent	689	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	3	3
Long-term debt (including amounts due within one year)(a)	1,135	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	951	533
Long-term debt (including amounts due within one year)(a)	33,863	23,644
Spent Nuclear Fuel Obligation, Noncurrent	835	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)	2,176	1,349
Spent Nuclear Fuel Obligation, Noncurrent	0	0
Due to Related Parties, Noncurrent	689	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	69	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	208	29
Long-term debt (including amounts due within one year)(a)	9,066	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	208	29
Long-term debt (including amounts due within one year)(a)	9,530	9,116
Spent Nuclear Fuel Obligation, Noncurrent	835	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	208	29
Long-term debt (including amounts due within one year)(a)	7,953	7,767
Spent Nuclear Fuel Obligation, Noncurrent	835	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)	1,577	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	48	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	35	294
Long-term debt (including amounts due within one year)(a)	7,695	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	35	294
Long-term debt (including amounts due within one year)(a)	8,832	7,069
Due to Related Parties, Noncurrent	209	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	35	294
Long-term debt (including amounts due within one year)(a)	8,832	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	209	213
PECO Energy Co [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Due to Related Parties, Noncurrent	184	184
Deferred Finance Costs, Net	14	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)	2,581	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)	3,002	2,786
Due to Related Parties, Noncurrent	205	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)	3,002	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	205	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	190	190
Deferred Finance Costs, Net	8	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	211	213
Long-term debt (including amounts due within one year)(a)	1,820	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	211	213
Long-term debt (including amounts due within one year)(a)	2,136	2,044
Due to Related Parties, Noncurrent	275	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	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	208	210
Long-term debt (including amounts due within one year)(a)	2,136	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	0
Long-term debt (including amounts due within one year)(a)	0	0
Due to Related Parties, Noncurrent	275	264
Pepco Holdings LLC [Member] | Successor [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Preferred Stock, Value, Issued	0
Pepco Holdings LLC [Member] | Predecessor [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Preferred Stock, Value, Issued		183
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	500
Long-term debt (including amounts due within one year)(a)	6,073
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	500
Long-term debt (including amounts due within one year)(a)	6,351
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	500
Long-term debt (including amounts due within one year)(a)	5,752
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)	599
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)	2,349	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)	3,030	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)	3,028	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		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		105
Long-term debt (including amounts due within one year)(a)	1,381	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
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		105
Long-term debt (including amounts due within one year)(a)	1,279	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
Long-term debt (including amounts due within one year)(a)	102	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)	1,180	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)	1,384	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)	1,083	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)	$ 301	$ 280

Fair Value of Financial Asset69

Fair Value of Financial Assets and Liabilities - Fair Value Measurements of Assets and Liabilities, Recurring and Nonrecurring (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2016	Jun. 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	$ 1,303			$ 1,236
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents				5,766
Cash and Cash Equivalents, Fair Value Disclosure				5,766
U.S. Treasury and agencies
Fixed income subtotal	227
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	(442)			(374)
Derivative Liability, Current	152			205
Derivative, Collateral, Right to Reclaim Cash	71			52
Derivative Asset, Notional Amount	1,303			1,236
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	16			8
Proprietary Trading Liabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability	(131)			(127)
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	(48)			(3)
Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	393
Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	5,329
Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	2,159
US Treasury And Government Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	25			8
CorporateDebtSecuritiesZoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	9			46
Other Fixed income Zoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure				1
Economic hedge Interest and Currency [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	28			20
Commodity Derivative Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	1,242			2,069
Pledged Assets For Zion Station Decommissioning [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	161			205
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Net assets (liabilities) excluded from nuclear decommissioning trust fund investments				1
Equity Funds Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	6			6
Fixed Income Securities Zion Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	34			55
MiddleMarketLending Zoin Decom [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	106			127
Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	14
Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	49			48
6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	83			36
Other Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	37			33
Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	127			130
Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	(4,821)			(5,157)
Interest rate and foreign currency derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	63			54
Designated as Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	47			25
Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	5,936			7,096
Proprietary Trading Interest and Currency Derivative [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	11			15
Effectsofnettingandallocationofcollateral1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	(23)			(6)
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	1,311			2
Cash and Cash Equivalents, Fair Value Disclosure	1,311			2
FinancialAssetsFairValueDisclosure1	13,826			18,556
Deferred Compensation Liability, Current and Noncurrent	(127)			(99)
Financial Liabilities Fair Value Disclosure	721			678
FinancialAssetLiabilitiesNetFairValueDisclosure1	(13,105)			(17,878)
Fair Value, Measurements, Recurring [Member] | Commodity Derivative Liabilites [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability	(569)			(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	(5,779)			(6,827)
Fair Value, Measurements, Recurring [Member] | Interestrateandforeigncurrencyderivativeliabilities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability	(25)			(16)
Fair Value, Measurements, Recurring [Member] | EconomicHedgingInstrumentLiabilites1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability	(19)			(3)
Fair Value, Measurements, Recurring [Member] | ProprietaryTradingLiabilitiesInterestandFX [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability	(9)
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	(5,341)			(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	(23)			(16)
Fair Value, Measurements, Recurring [Member] | Proprietary Trading Liabilities Interest and FX [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability				(12)
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	(26)			(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	10,785			10,345
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	2,477			2,660
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	124			125
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	124
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				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	44			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	1,481			1,338
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	459			537
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	399
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	46			35
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	46
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	285			326
Fair Value, Measurements, Recurring [Member] | Pledged Assets For Zion Station Decommissioning [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	81			105
Fair Value, Measurements, Recurring [Member] | Cash Equivalent Zion [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	15			17
Cash and Cash Equivalents, Fair Value Disclosure	15			17
Fair Value, Measurements, Recurring [Member] | MiddleMarketLending Zoin Decom [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	81
Fair Value, Measurements, Recurring [Member] | Private Equity Funds, Domestic [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure				4,902
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	4,428			4,328
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	399			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	465			428
Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents				311
Cash and Cash Equivalents, Fair Value Disclosure				311
Investments, Fair Value Disclosure	81
Fair Value, Measurements, Recurring [Member] | Other [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure				216
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents				5,766
Cash and Cash Equivalents, Fair Value Disclosure				5,766
U.S. Treasury and agencies
Fixed income subtotal	130
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Collateral received from counterparties, net of collateral paid to counterparties	123			476
Fair Value, Inputs, Level 1 [Member] | Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	381
Fair Value, Inputs, Level 1 [Member] | Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	3,205
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	1,908
Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0
Fair Value, Inputs, Level 1 [Member] | Economic hedge Interest and Currency [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	0			0
Fair Value, Inputs, Level 1 [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0
Fair Value, Inputs, Level 1 [Member] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	49			48
Fair Value, Inputs, Level 1 [Member] | 6311 Life Insurance [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]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	1,311
Cash and Cash Equivalents, Fair Value Disclosure	1,311
FinancialAssetsFairValueDisclosure1	6,579			10,372
Deferred Compensation Liability, Current and Noncurrent	0			0
Financial Liabilities Fair Value Disclosure	48			(25)
FinancialAssetLiabilitiesNetFairValueDisclosure1	(6,531)			(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	49			(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	(1,456)			(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	(24)			(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	1			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
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	(9)
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	(1,431)			(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
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Liabilities Interest and FX [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability				(12)
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	(10)			(12)
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	423			763
Cash and Cash Equivalents, Fair Value Disclosure	423			763
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	136			178
Cash and Cash Equivalents, Fair Value Disclosure	136			178
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	22
Cash and Cash Equivalents, Fair Value Disclosure	22
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	5,038			4,550
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
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure				125
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
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
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	1,452			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	23			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
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	0			0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure				390
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
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure				35
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	59			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
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	38			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	15			0
Cash and Cash Equivalents, Fair Value Disclosure	15			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			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	23			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
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure				105
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Private Equity Funds, Domestic [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure				3,008
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure				1,894
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	1,452			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
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]
Cash equivalents				219
Cash and Cash Equivalents, Fair Value Disclosure				219
Investments, Fair Value Disclosure	81
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
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	25			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	(1,309)			(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			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
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	1,343			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	10			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	(7)			(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
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure				216
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents				0
Cash and Cash Equivalents, Fair Value Disclosure				0
U.S. Treasury and agencies
Fixed income subtotal	77
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Collateral received from counterparties, net of collateral paid to counterparties	279			557
Fair Value, Inputs, Level 2 [Member] | Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	12
Fair Value, Inputs, Level 2 [Member] | Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	215
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,910
Fair Value, Inputs, Level 2 [Member] | Economic hedge Interest and Currency [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	28			20
Fair Value, Inputs, Level 2 [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	14
Fair Value, Inputs, Level 2 [Member] | Mutual Funds [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] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	63			36
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
Cash and Cash Equivalents, Fair Value Disclosure	0			0
FinancialAssetsFairValueDisclosure1	3,134			3,521
Deferred Compensation Liability, Current and Noncurrent	(127)			(99)
Financial Liabilities Fair Value Disclosure	303			334
FinancialAssetLiabilitiesNetFairValueDisclosure1	(2,831)			(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	(150)			(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	(3,089)			(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	(73)			(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	(26)			(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)			(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
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	(3,012)			(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	(23)			(16)
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Liabilities Interest and FX [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability				0
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)			(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	2,555			2,465
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
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				1,824
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	44			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	29			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
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	9			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	60			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
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	425			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	285			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	17			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			17
Cash and Cash Equivalents, Fair Value Disclosure	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	6			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	11			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
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Private Equity Funds, Domestic [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure				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	2,328			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
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]
Cash equivalents				92
Cash and Cash Equivalents, Fair Value Disclosure				92
Investments, Fair Value Disclosure	0
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
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	71			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	(2,733)			(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	60			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	47			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	3,087			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			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	(16)			(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]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents				0
Cash and Cash Equivalents, Fair Value Disclosure				0
U.S. Treasury and agencies
Fixed income subtotal	20
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Collateral received from counterparties, net of collateral paid to counterparties	119			201
Fair Value, Inputs, Level 3 [Member] | Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0
Fair Value, Inputs, Level 3 [Member] | Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1
Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	249
Fair Value, Inputs, Level 3 [Member] | Economic hedge Interest and Currency [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	0			0
Fair Value, Inputs, Level 3 [Member] | Fixed Income Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	0
Fair Value, Inputs, Level 3 [Member] | Mutual Funds [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] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	20			0
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
Cash and Cash Equivalents, Fair Value Disclosure	0			0
FinancialAssetsFairValueDisclosure1	1,555			1,898
Deferred Compensation Liability, Current and Noncurrent	0			0
Financial Liabilities Fair Value Disclosure	370			369
FinancialAssetLiabilitiesNetFairValueDisclosure1	(1,185)			(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	(370)			(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	(1,234)			(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	(34)			(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
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
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
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	(898)			(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
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Liabilities Interest and FX [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability				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
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	715			670
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
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				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
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
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
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
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	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
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	758			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
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	25			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
Cash and Cash Equivalents, Fair Value Disclosure	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
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
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	25			22
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Private Equity Funds, Domestic [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] | Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	249			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	465			428
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]
Cash equivalents				0
Cash and Cash Equivalents, Fair Value Disclosure				0
Investments, Fair Value Disclosure	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	37			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	31			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	(779)			(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
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
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	1,506			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
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
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	164	$ (389)
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents				104
Cash and Cash Equivalents, Fair Value Disclosure				104
U.S. Treasury and agencies
Fixed income subtotal	43
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	(237)			(150)
Derivative Liability, Current	134			182
Alternative Investments, Fair Value Disclosure				2,765
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	(131)			(127)
Exelon Generation Co L L C [Member] | Cash Equivalents NDT [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	393
Exelon Generation Co L L C [Member] | Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	5,329
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	1,908
Exelon Generation Co L L C [Member] | Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	2,159
Exelon Generation Co L L C [Member] | Economic hedge Interest and Currency [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	28			20
Exelon Generation Co L L C [Member] | Commodity Derivative Assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	1,242			2,069
Exelon Generation Co L L C [Member] | Fixed Income Investments [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] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	18			17
Exelon Generation Co L L C [Member] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	17			13
Exelon Generation Co L L C [Member] | Other Investments [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	37			33
Exelon Generation Co L L C [Member] | Proprietary Trading [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	127			130
Exelon Generation Co L L C [Member] | Effects of netting and allocation of collateral [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	(4,820)			(5,157)
Exelon Generation Co L L C [Member] | Economic Hedges [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset				7,096
Exelon Generation Co L L C [Member] | Interest rate and foreign currency derivative assets [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	16			29
Exelon Generation Co L L C [Member] | Designated as Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	0			0
Exelon Generation Co L L C [Member] | Economic Hedging Instrument [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	5,935
Exelon Generation Co L L C [Member] | Proprietary Trading Interest and Currency Derivative [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	11			15
Exelon Generation Co L L C [Member] | Effectsofnettingandallocationofcollateral1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	(23)			(6)
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	42
Cash and Cash Equivalents, Fair Value Disclosure	42
FinancialAssetsFairValueDisclosure1	12,326			12,815
Deferred Compensation Liability, Current and Noncurrent	(30)			(30)
Financial Liabilities Fair Value Disclosure	401			362
FinancialAssetLiabilitiesNetFairValueDisclosure1	(11,925)			(12,453)
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure				2,660
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	(348)			(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	(5,558)			(6,580)
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	(23)			(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)			(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	(9)
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	(5,341)			(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	(21)			(16)
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Liabilities Interest and FX [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability				(12)
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	(26)			(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	10,785			10,345
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	2,477
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	124			125
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	124
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				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	44			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	1,481			1,338
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	459			537
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	399
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	46			35
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	46
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	285			326
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Pledged Assets For Zion Station Decommissioning [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	81			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	15			17
Cash and Cash Equivalents, Fair Value Disclosure	15			17
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | MiddleMarketLending Zoin Decom [Member]
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	81
Exelon Generation Co L L C [Member] | Fair Value, Measurements, Recurring [Member] | Private Equity Funds, Domestic [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure				4,902
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	4,428			4,328
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure	399			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	465			428
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]
Cash equivalents				311
Cash and Cash Equivalents, Fair Value Disclosure				311
Investments, Fair Value Disclosure	8
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
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents				104
Cash and Cash Equivalents, Fair Value Disclosure				104
U.S. Treasury and agencies
Fixed income subtotal	26
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	3,205
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [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] | Economic hedge Interest and Currency [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fixed Income Investments [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] | Mutual Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	18			17
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | 6311 Life Insurance [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]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	42
Cash and Cash Equivalents, Fair Value Disclosure	42
FinancialAssetsFairValueDisclosure1	5,206			4,679
Deferred Compensation Liability, Current and Noncurrent	0			0
Financial Liabilities Fair Value Disclosure	48			25
FinancialAssetLiabilitiesNetFairValueDisclosure1	(5,158)			(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	49			(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	(1,456)			(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	(24)			(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	1			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
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	(9)
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	(1,431)			(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
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Liabilities Interest and FX [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability				(12)
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	(10)			(12)
Exelon Generation Co L L C [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	332			329
Cash and Cash Equivalents, Fair Value Disclosure	332			329
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	97			121
Cash and Cash Equivalents, Fair Value Disclosure	97			121
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	5,038			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	381
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
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure				125
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
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
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	1,452			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	23			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
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	0			0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure				390
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
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure				35
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
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	59			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
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	38			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	15			0
Cash and Cash Equivalents, Fair Value Disclosure	15			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			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	23			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
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure				105
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Private Equity Funds, Domestic [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure				3,008
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Alternative Investments, Fair Value Disclosure				1,894
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	1,452			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
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]
Cash equivalents				219
Cash and Cash Equivalents, Fair Value Disclosure				219
Investments, Fair Value Disclosure	8
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
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	25			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	(1,308)			(1,964)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedges [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset				1,922
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			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
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	1,342
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	10			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	(7)			(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
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 2 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents				0
Cash and Cash Equivalents, Fair Value Disclosure				0
U.S. Treasury and agencies
Fixed income subtotal	17
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Private Equity Funds [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	215
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	1,910
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Economic hedge Interest and Currency [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	28
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fixed Income Investments [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] | Mutual Funds [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] | 6311 Life Insurance [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	17			13
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	0
Cash and Cash Equivalents, Fair Value Disclosure	0
Investments, Fair Value Disclosure	12
FinancialAssetsFairValueDisclosure1	3,027			3,473
Deferred Compensation Liability, Current and Noncurrent	(30)			(30)
Financial Liabilities Fair Value Disclosure	204			265
FinancialAssetLiabilitiesNetFairValueDisclosure1	(2,823)			(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	(150)			(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	(3,089)			(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	(73)			(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	(24)			(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)			(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
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	(3,012)			(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	(21)			(16)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Liabilities Interest and FX [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability				0
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)			(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	2,555			2,465
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
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				1,824
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	44			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	29			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
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	9			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	60			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
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				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	425			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	285			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	17			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			17
Cash and Cash Equivalents, Fair Value Disclosure	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	6			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	11			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
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Private Equity Funds, Domestic [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] | Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	2,328			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
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]
Cash equivalents				92
Cash and Cash Equivalents, Fair Value Disclosure				92
Investments, Fair Value Disclosure	0
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
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	71			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	(2,733)			(2,629)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedges [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset				3,467
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	13			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
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	3,087
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			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	(16)			(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, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents				0
Cash and Cash Equivalents, Fair Value Disclosure				0
U.S. Treasury and agencies
Fixed income subtotal	0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Private Equity Funds [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 3 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	249
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Economic hedge Interest and Currency [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	0
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fixed Income Investments [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] | Mutual Funds [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] | 6311 Life Insurance [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]
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	1,535			1,898
Deferred Compensation Liability, Current and Noncurrent	0			0
Financial Liabilities Fair Value Disclosure	149			122
FinancialAssetLiabilitiesNetFairValueDisclosure1	(1,386)			(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	(149)			(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	(1,013)			(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	(34)			(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
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
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
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	(898)			(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
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Proprietary Trading Liabilities Interest and FX [Domain]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Liability				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
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	715			670
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
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				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
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
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
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
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	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
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
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	758			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
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	25			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
Cash and Cash Equivalents, Fair Value Disclosure	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
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
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	25			22
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Private Equity Funds, Domestic [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] | Fixed Income Securities [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	249			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	465			428
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]
Cash equivalents				0
Cash and Cash Equivalents, Fair Value Disclosure				0
Investments, Fair Value Disclosure	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	37			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	31			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	(779)			(564)
Exelon Generation Co L L C [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Economic Hedges [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset				1,707
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
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
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	1,506
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
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
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
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Derivative Asset	0
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]
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	344
Cash and Cash Equivalents, Fair Value Disclosure	344
Derivative Asset	1
FinancialAssetsFairValueDisclosure1	473
Derivative Liability	0
Deferred Compensation Liability, Current and Noncurrent	(28)
Financial Liabilities Fair Value Disclosure	28
FinancialAssetLiabilitiesNetFairValueDisclosure1	445
U.S. Treasury and agencies
Collateral Amount Offset Against Fair Value Of Derivative Current Asset	(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
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
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	129
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
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
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	42
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	13			16
Cash and Cash Equivalents, Fair Value Disclosure	13			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			18
Cash and Cash Equivalents, Fair Value Disclosure	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	344
Cash and Cash Equivalents, Fair Value Disclosure	344
Derivative Asset	1
FinancialAssetsFairValueDisclosure1	417
Derivative Liability	0
Deferred Compensation Liability, Current and Noncurrent	0
Financial Liabilities Fair Value Disclosure	0
FinancialAssetLiabilitiesNetFairValueDisclosure1	417
U.S. Treasury and agencies
Collateral Amount Offset Against Fair Value Of Derivative Current Asset	(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
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
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
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
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
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
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
Cash and Cash Equivalents, Fair Value Disclosure	0
FinancialAssetsFairValueDisclosure1	36
Derivative Liability	0
Deferred Compensation Liability, Current and Noncurrent	(28)
Financial Liabilities Fair Value Disclosure	28
FinancialAssetLiabilitiesNetFairValueDisclosure1	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
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
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
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
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
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
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
Cash and Cash Equivalents, Fair Value Disclosure	0
FinancialAssetsFairValueDisclosure1	20
Derivative Liability	0
Deferred Compensation Liability, Current and Noncurrent	0
Financial Liabilities Fair Value Disclosure	0
FinancialAssetLiabilitiesNetFairValueDisclosure1	20
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
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
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
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	20
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
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	20
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]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	184			271
Cash and Cash Equivalents, Fair Value Disclosure	184			271
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Cash surrender value of life insurance investments excluded from Rabbi Trust investments				14
PECO Energy Co [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	18			20
FinancialAssetsFairValueDisclosure1	202			291
Deferred Compensation Liability, Current and Noncurrent	(10)			(12)
Financial Liabilities Fair Value Disclosure	10			12
FinancialAssetLiabilitiesNetFairValueDisclosure1	192			(279)
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	0			0
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			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			12
PECO Energy Co [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	184			271
Cash and Cash Equivalents, Fair Value Disclosure	184			271
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]
Investments, Fair Value Disclosure	7			8
FinancialAssetsFairValueDisclosure1	191			279
Deferred Compensation Liability, Current and Noncurrent	0			0
Financial Liabilities Fair Value Disclosure	0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1	191			(279)
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	0			0
PECO Energy Co [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	22			27
Cash and Cash Equivalents, Fair Value Disclosure	22			27
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			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
PECO Energy Co [Member] | Fair Value, Inputs, Level 2 [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
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]
FinancialAssetsFairValueDisclosure1	11			12
Deferred Compensation Liability, Current and Noncurrent	(10)			(12)
Financial Liabilities Fair Value Disclosure	10			12
FinancialAssetLiabilitiesNetFairValueDisclosure1	1			0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	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			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
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			12
PECO Energy Co [Member] | Fair Value, Inputs, Level 3 [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
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]
FinancialAssetsFairValueDisclosure1	0			0
Deferred Compensation Liability, Current and Noncurrent	0			0
Financial Liabilities Fair Value Disclosure	0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1	0			0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	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
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
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
Baltimore Gas and Electric Company [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	20			25
Cash and Cash Equivalents, Fair Value Disclosure	20			25
Baltimore Gas and Electric Company [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Investments, Fair Value Disclosure	4			4
FinancialAssetsFairValueDisclosure1	24			29
Deferred Compensation Liability, Current and Noncurrent	(4)			(4)
Financial Liabilities Fair Value Disclosure	4			4
FinancialAssetLiabilitiesNetFairValueDisclosure1	20			(25)
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	0			0
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
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
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	20			25
Cash and Cash Equivalents, Fair Value Disclosure	20			25
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]
Investments, Fair Value Disclosure	4			4
FinancialAssetsFairValueDisclosure1	24			29
Deferred Compensation Liability, Current and Noncurrent	0			0
Financial Liabilities Fair Value Disclosure	0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1	24			(29)
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	0			0
Baltimore Gas and 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			6
Cash and Cash Equivalents, Fair Value Disclosure	5			6
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	2			2
Cash and Cash Equivalents, Fair Value Disclosure	2			2
Baltimore Gas and 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	3
Cash and Cash Equivalents, Fair Value Disclosure	3
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
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
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 2 [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
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]
FinancialAssetsFairValueDisclosure1	0			0
Deferred Compensation Liability, Current and Noncurrent	(4)			(4)
Financial Liabilities Fair Value Disclosure	4			4
FinancialAssetLiabilitiesNetFairValueDisclosure1	(4)			4
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	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
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
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
Baltimore Gas and Electric Company [Member] | Fair Value, Inputs, Level 3 [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
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]
FinancialAssetsFairValueDisclosure1	0			0
Deferred Compensation Liability, Current and Noncurrent	0			0
Financial Liabilities Fair Value Disclosure	0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1	0			0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	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
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
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
Potomac Electric Power Company [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	155
Cash and Cash Equivalents, Fair Value Disclosure	155
FinancialAssetsFairValueDisclosure1	254			70
Derivative Liability				0
Deferred Compensation Liability, Current and Noncurrent	(5)			(6)
Financial Liabilities Fair Value Disclosure	5			6
FinancialAssetLiabilitiesNetFairValueDisclosure1	249			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	99			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			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			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	42			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	155			2
Cash and Cash Equivalents, Fair Value Disclosure	155			2
Investments, Fair Value Disclosure	0
FinancialAssetsFairValueDisclosure1	198			13
Derivative Liability				0
Deferred Compensation Liability, Current and Noncurrent	0			0
Financial Liabilities Fair Value Disclosure	0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1	198			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	5			5
Cash and Cash Equivalents, Fair Value Disclosure	5			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			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			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
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
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			38
Derivative Liability				0
Deferred Compensation Liability, Current and Noncurrent	(5)			(6)
Financial Liabilities Fair Value Disclosure	5			6
FinancialAssetLiabilitiesNetFairValueDisclosure1	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			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			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			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	20			19
Derivative Liability				0
Deferred Compensation Liability, Current and Noncurrent	0			0
Financial Liabilities Fair Value Disclosure	0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1	20			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	20			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
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	20			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
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	12			0
Cash and Cash Equivalents, Fair Value Disclosure	12			0
Derivative Asset	1
FinancialAssetsFairValueDisclosure1	12			0
Derivative Liability				0
Deferred Compensation Liability, Current and Noncurrent	(1)			(1)
Financial Liabilities Fair Value Disclosure	1			1
FinancialAssetLiabilitiesNetFairValueDisclosure1	11			(1)
U.S. Treasury and agencies
Collateral Amount Offset Against Fair Value Of Derivative Current Asset	(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
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
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
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
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	12			0
Cash and Cash Equivalents, Fair Value Disclosure	12			0
Investments, Fair Value Disclosure	0			0
Derivative Asset	1
FinancialAssetsFairValueDisclosure1	12			0
Derivative Liability				0
Deferred Compensation Liability, Current and Noncurrent	0			0
Financial Liabilities Fair Value Disclosure	0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1	12			0
U.S. Treasury and agencies
Collateral Amount Offset Against Fair Value Of Derivative Current Asset	(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			5
Cash and Cash Equivalents, Fair Value Disclosure	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
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
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
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
Cash and Cash Equivalents, Fair Value Disclosure	0			0
Investments, Fair Value Disclosure				0
FinancialAssetsFairValueDisclosure1	0			0
Derivative Liability				0
Deferred Compensation Liability, Current and Noncurrent	(1)			(1)
Financial Liabilities Fair Value Disclosure	1			1
FinancialAssetLiabilitiesNetFairValueDisclosure1	(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
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
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
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
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
Cash and Cash Equivalents, Fair Value Disclosure	0			0
Investments, Fair Value Disclosure				0
FinancialAssetsFairValueDisclosure1	0			0
Derivative Liability				0
Deferred Compensation Liability, Current and Noncurrent	0			0
Financial Liabilities Fair Value Disclosure	0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1	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
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
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
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
Atlantic City Electric Company [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	176			30
Cash and Cash Equivalents, Fair Value Disclosure	176			30
FinancialAssetsFairValueDisclosure1	176			30
Derivative Liability				0
Deferred Compensation Liability, Current and Noncurrent	0			0
Financial Liabilities Fair Value Disclosure	0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1	176			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
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
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
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
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	176			30
Cash and Cash Equivalents, Fair Value Disclosure	176			30
Investments, Fair Value Disclosure	0			0
FinancialAssetsFairValueDisclosure1	176			30
Derivative Liability				0
Deferred Compensation Liability, Current and Noncurrent	0			0
Financial Liabilities Fair Value Disclosure	0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1	176			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	4			3
Cash and Cash Equivalents, Fair Value Disclosure	4			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			18
Cash and Cash Equivalents, Fair Value Disclosure	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
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
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
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
Cash and Cash Equivalents, Fair Value Disclosure	0			0
Investments, Fair Value Disclosure				0
FinancialAssetsFairValueDisclosure1	0			0
Derivative Liability				0
Deferred Compensation Liability, Current and Noncurrent	0			0
Financial Liabilities Fair Value Disclosure	0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1	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
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
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
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
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
Cash and Cash Equivalents, Fair Value Disclosure	0			0
Investments, Fair Value Disclosure				0
FinancialAssetsFairValueDisclosure1	0			0
Derivative Liability				0
Deferred Compensation Liability, Current and Noncurrent	0			0
Financial Liabilities Fair Value Disclosure	0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1	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
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
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
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
Commonwealth Edison Co [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	700			29
Cash and Cash Equivalents, Fair Value Disclosure	700			29
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	(203)			(224)
Derivative Liability, Current	18			23
Commonwealth Edison Co [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
FinancialAssetsFairValueDisclosure1	700			29
Deferred Compensation Liability, Current and Noncurrent	(8)			(8)
Financial Liabilities Fair Value Disclosure	229			255
FinancialAssetLiabilitiesNetFairValueDisclosure1	471			226
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	(221)			(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
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
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
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	700			29
Cash and Cash Equivalents, Fair Value Disclosure	700			29
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]
FinancialAssetsFairValueDisclosure1	700			29
Deferred Compensation Liability, Current and Noncurrent	0			0
Financial Liabilities Fair Value Disclosure	0			0
FinancialAssetLiabilitiesNetFairValueDisclosure1	700			(29)
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	0			0
Commonwealth Edison Co [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	36			38
Cash and Cash Equivalents, Fair Value Disclosure	36			38
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Restricted cash member [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Cash equivalents	2			2
Cash and Cash Equivalents, Fair Value Disclosure	2			2
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
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
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
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 2 [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
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]
FinancialAssetsFairValueDisclosure1	0			0
Deferred Compensation Liability, Current and Noncurrent	(8)			(8)
Financial Liabilities Fair Value Disclosure	8			8
FinancialAssetLiabilitiesNetFairValueDisclosure1	(8)			8
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	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
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
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
Commonwealth Edison Co [Member] | Fair Value, Inputs, Level 3 [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
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]
FinancialAssetsFairValueDisclosure1	0			0
Deferred Compensation Liability, Current and Noncurrent	0			0
Financial Liabilities Fair Value Disclosure	221			247
FinancialAssetLiabilitiesNetFairValueDisclosure1	(221)			(247)
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]
Derivative Liability, Noncurrent	(221)			(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
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
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

Fair Value of Financial Asset70

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
	Jun. 30, 2016	Jun. 30, 2016	Mar. 23, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Mar. 31, 2016	Mar. 24, 2016	Dec. 31, 2015	Mar. 31, 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	$ 1,185,000,000	$ 1,185,000,000		$ 1,536,000,000	$ 1,185,000,000	$ 1,536,000,000	$ 1,547,000,000		$ 1,529,000,000	$ 1,484,000,000	$ 1,501,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	423,000,000			(5,000,000)	(427,000,000)	35,000,000
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	0			(2,000,000)	2,000,000	(1,000,000)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Regulatory assets	52,000,000			25,000,000	38,000,000	1,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	109,000,000			123,000,000	206,000,000	192,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	2,000,000			(7,000,000)	4,000,000	24,000,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(260,000,000)			177,000,000	(40,000,000)	358,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	65,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements				33,000,000	91,000,000	62,000,000
Purchases, sales, issuances and settlements
Purchases	109,000,000			123,000,000	206,000,000	192,000,000
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	32,000,000			(30,000,000)	(82,000,000)	18,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	0			11,000,000	2,000,000	15,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	0			30,000,000	7,000,000	35,000,000
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	8,000,000			(7,000,000)	(12,000,000)	17,000,000
Included in noncurrent payables to affiliates						17,000,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Regulatory assets	8,000,000			7,000,000	12,000,000
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	164,000,000			(389,000,000)
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)	4,000,000				11,000,000
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	1,386,000,000	1,386,000,000		1,759,000,000	1,386,000,000	1,759,000,000	1,792,000,000		1,776,000,000	1,725,000,000	1,708,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	424,000,000			(5,000,000)	(428,000,000)	35,000,000
Total realized / unrealized gains (losses)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Noncurrent Payables To Affiliates	(8,000,000)			7,000,000	12,000,000	(17,000,000)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Included In Nuclear Decommissioning Payable	0			(2,000,000)	2,000,000	(1,000,000)
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	109,000,000			123,000,000	206,000,000	192,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	2,000,000			(7,000,000)	4,000,000	24,000,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(261,000,000)			177,000,000	(41,000,000)	358,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	65,000,000			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements				33,000,000	91,000,000	62,000,000
Purchases, sales, issuances and settlements
Purchases	109,000,000			123,000,000	206,000,000	192,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3				0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3				0
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)	40,000,000				15,000,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Change In Collateral	32,000,000			(30,000,000)	(82,000,000)	18,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	0			11,000,000	2,000,000	15,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	0			30,000,000	7,000,000	35,000,000
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	715,000,000	715,000,000		667,000,000	715,000,000	667,000,000	684,000,000		670,000,000	612,000,000	605,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	(4,000,000)			2,000,000	6,000,000	(4,000,000)
Total realized / unrealized gains (losses)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Noncurrent Payables To Affiliates	(8,000,000)			7,000,000	12,000,000	(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	85,000,000			79,000,000	119,000,000	107,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	(1,000,000)			0	(1,000,000)	8,000,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	3,000,000				4,000,000	3,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(65,000,000)			(33,000,000)	(91,000,000)	(62,000,000)
Purchases, sales, issuances and settlements
Purchases	85,000,000			79,000,000	119,000,000	107,000,000
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	25,000,000	25,000,000		41,000,000	25,000,000	41,000,000	25,000,000		22,000,000	44,000,000	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	0			(2,000,000)	2,000,000	(1,000,000)
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			1,000,000	1,000,000	1,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	0			(2,000,000)	0	11,000,000
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			1,000,000	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	609,000,000	609,000,000		1,021,000,000	609,000,000	1,021,000,000	1,047,000,000		1,051,000,000	1,066,000,000	1,050,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	428,000,000			(7,000,000)	(434,000,000)	39,000,000
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	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	23,000,000			16,000,000	82,000,000	57,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	(1,000,000)			(5,000,000)	(3,000,000)	5,000,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(264,000,000)				(45,000,000)	355,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	0			0	0	0
Purchases, sales, issuances and settlements
Purchases	23,000,000			16,000,000	82,000,000	57,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3				30,000,000
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	32,000,000			(30,000,000)	(82,000,000)	18,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	0			11,000,000	2,000,000	11,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	0				(7,000,000)	35,000,000
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	37,000,000	37,000,000		30,000,000	37,000,000	30,000,000	36,000,000		33,000,000	3,000,000	3,000,000
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	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	1,000,000			27,000,000	4,000,000	27,000,000
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	1,000,000			27,000,000	4,000,000	27,000,000
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	0			0	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3				0	0	0
Commonwealth Edison Co [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				0
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
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Regulatory assets				18,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases				0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales				0
Purchases, sales, issuances and settlements
Purchases				0
Ending balance				(223,000,000)		(223,000,000)
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
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	(221,000,000)	(221,000,000)		(223,000,000)	(221,000,000)	(223,000,000)	(265,000,000)		(247,000,000)	(241,000,000)	(207,000,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	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
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain Loss Included In Nuclear Decommissioning Payable	0				0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Included In Regulatory assets	44,000,000				26,000,000	(16,000,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	0				0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	0				0	0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)					0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	0				0	0
Purchases, sales, issuances and settlements
Purchases	0				0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3						0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3						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
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
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] | 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
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 Value								0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		1,000,000
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	20,000,000		20,000,000			19,000,000	19,000,000	19,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			(1,000,000)	(2,000,000)		(3,000,000)
Total realized / unrealized gains (losses)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases			0	(1,000,000)		(1,000,000)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)			1,000,000	1,000,000		2,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements						(1,000,000)
Purchases, sales, issuances and settlements
Purchases			0	(1,000,000)		(1,000,000)
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	20,000,000	20,000,000			20,000,000		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	(1,000,000)	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)	1,000,000	1,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	0	0		0
Purchases, sales, issuances and settlements
Purchases	(1,000,000)	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	3,000,000		3,000,000			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	0		0
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			0
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				3,000,000		3,000,000
Total realized / unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0
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	(1,000,000)			(1,000,000)	(1,000,000)	(1,000,000)
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	(1,000,000)			(1,000,000)	(1,000,000)	(1,000,000)
Ending balance				20,000,000		20,000,000
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	20,000,000	$ 20,000,000		20,000,000	20,000,000	20,000,000	$ 20,000,000		$ 19,000,000	$ 19,000,000	$ 18,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	(1,000,000)			(2,000,000)
Total realized / unrealized gains (losses)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases					2,000,000	3,000,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	$ 1,000,000			$ 1,000,000
Purchases, sales, issuances and settlements
Purchases					$ 2,000,000	$ 3,000,000

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 ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2016	Jun. 30, 2016	Mar. 23, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 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	$ (462)			$ (17)	$ (413)	$ (27)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	(274)			171	(20)	340
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	34			10	(21)	(12)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	10			4	(25)	15
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	5			2	7	4
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	4			2	5	3
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	(462)			(17)	(413)	(27)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	(274)			171	(20)	340
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	34			10	(21)	(12)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	10			4	(25)	15
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	4			2	6	4
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	3			2	4	3
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			$ (17)			3
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)			$ 1			2
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		$ 1
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					2	3
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)					2	2
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	(423)			5	427	(35)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(260)			177	(40)	358
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	109			123	206	192
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	(424)			5	428	(35)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(261)			177	(41)	358
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	$ 109			123	$ 206	$ 192
Fair Value, Inputs, Level 3 [Member] | Commonwealth Edison Co [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, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases				$ 0

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 ($)	6 Months Ended	12 Months Ended
	Jun. 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	$ 493,000,000	$ 857,000,000
Exelon Generation Co L L C [Member] | Derivative [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Forward power price assets	8	11
Forward gas price assets	1.74	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	$ 10.19	$ 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	353.00%	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)	$ (7,000,000)
Exelon Generation Co L L C [Member] | Proprietary Trading [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Fair Value Inputs [Abstract]
Forward power price assets	12	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	84	78
Commonwealth Edison Co [Member] | Derivative [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ (221,000,000)	$ (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%)
Commonwealth Edison Co [Member] | Derivative [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Fair Value Inputs [Abstract]
Forward heat rate	(9.00%)		(9.00%)

Derivative Financial Instrume73

Derivative Financial Instruments - Summary of Interest Rate and Foreign Currency Hedges (Details) - USD ($) $ in Millions		Jun. 30, 2016	Dec. 31, 2015
Derivative [Line Items]
Derivative Asset, Current		$ 759	$ 1,365
Derivative Asset, Noncurrent		546	758
Derivative Liability, Current		152	205
Derivative Liability, Noncurrent		442	374
Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative Asset, Current		759	1,365
Derivative Asset, Noncurrent		499	733
Derivative Liability, Current		134	182
Derivative Liability, Noncurrent		237	150
InterestRateAndForeignExchangeContract [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative Asset, Current		9	15
Derivative Asset, Noncurrent		7	14
Derivative Asset		16	29
Derivative Liability, Current		(9)	(8)
Derivative Liability, Noncurrent		(14)	(8)
Derivative Liability		(23)	(16)
Derivative, Fair Value, Net		(7)	13
InterestRateAndForeignExchangeContract [Member] | Exelon Generation Co L L C [Member] | Economic Hedges [Member]
Derivative [Line Items]
Derivative Asset, Current		14	10
Derivative Asset, Noncurrent		14	10
Derivative Asset		28	20
Derivative Liability, Current		(9)	(2)
Derivative Liability, Noncurrent		(10)	(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		(11)	(5)
Derivative Asset, Noncurrent		(12)	(1)
Derivative Asset		(23)	(6)
Derivative Liability, Current		12	11
Derivative Liability, Noncurrent		14	4
Derivative Liability		26	15
Derivative, Fair Value, Net		3	9
Interest Rate Swap [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative Liability, Current		4
Derivative [Member]
Derivative [Line Items]
Derivative Asset, Current		750	1,350
Derivative Asset, Noncurrent		492	719
Derivative Asset		1,242	2,069
Derivative Liability, Current		143	197
Derivative Liability, Noncurrent		426	366
Derivative Liability		569	563
Derivative, Fair Value, Net		673	1,506
Derivative [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative Asset, Current	[1]	750	1,350
Derivative Asset, Noncurrent	[1]	492	719
Derivative Asset	[1]	1,242	2,069
Derivative Liability, Current	[1]	125	174
Derivative Liability, Noncurrent	[1]	223	142
Derivative Liability	[1]	348	316
Derivative, Fair Value, Net	[1]	894	1,753
Not Designated as Hedging Instrument [Member] | InterestRateAndForeignExchangeContract [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative Asset, Current		6	10
Derivative Asset, Noncurrent		5	5
Derivative Asset		11	15
Derivative Liability, Current		(4)	(9)
Derivative Liability, Noncurrent		(5)	(3)
Derivative Liability		(9)	(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		54	39
Derivative Asset		63	54
Derivative Liability, Current		(9)	(8)
Derivative Liability, Noncurrent		(16)	(8)
Derivative Liability		(25)	(16)
Derivative, Fair Value, Net		38	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		(13)	(8)
Derivative Liability		(21)	(16)
Derivative, Fair Value, Net		(21)	(16)
Designated as Hedging Instrument [Member] | InterestRateAndForeignExchangeContract [Member] | Corporate, Non-Segment [Member]
Derivative [Line Items]
Derivative Asset, Current		0	0
Derivative Asset, Noncurrent		47	25
Derivative Asset		47	25
Derivative Liability, Current		0	0
Derivative Liability, Noncurrent		(2)	0
Derivative Liability		(2)	0
Derivative, Fair Value, Net		$ 45	$ 25
[1]	.

Derivative Financial Instrume74

Derivative Financial Instruments - Summary of Gains and Losses on Hedges (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Derivative [Line Items]
Income taxes		$ 102	$ 327	$ 285	$ 690
Gain (Loss) on Cash Flow Hedge Ineffectiveness, Net	[1]	4		6
Derivative, Loss on Derivative		3
Increase (Decrease) in Fair Value of Hedged Item in Price Risk Fair Value Hedge			16		9
Gain (Loss) on Fair Value Hedges Recognized in Earnings			(11)		(1)
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value		16		16		$ 8
Exelon Generation Co L L C [Member]
Derivative [Line Items]
Income taxes		(31)	$ 181	120	407
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		(1)		(16)
Interest Rate Swap [Member] | Fair Value Hedging [Member]
Derivative [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings		$ 5		22
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 six months ended June 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		Jun. 30, 2016	Mar. 23, 2016	Dec. 31, 2015
Derivative [Line Items]
Derivative Asset, Current		$ 759		$ 1,365
Derivative Asset, Noncurrent		546		758
Derivative Liability, Current		(152)		(205)
Derivative Liability, Noncurrent		(442)		(374)
Derivative [Member]
Derivative [Line Items]
Derivative Asset, Current		750		1,350
Derivative Asset, Noncurrent		492		719
Total mark-to-market derivative net assets (liabilities)		673		1,506
Total mark-to-market derivative assets		1,242		2,069
Derivative Liability, Current		(143)		(197)
Derivative Liability, Noncurrent		(426)		(366)
Total mark-to-market derivative liabilities		(569)		(563)
Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative Asset, Current		759		1,365
Derivative Asset, Noncurrent		499		733
Derivative Liability, Current		(134)		(182)
Derivative Liability, Noncurrent		(237)		(150)
Exelon Generation Co L L C [Member] | Economic Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Current		4,089		5,236
Derivative Asset, Noncurrent		1,846		1,860
Total mark-to-market derivative net assets (liabilities)		377		516
Total mark-to-market derivative assets		5,935		7,096
Derivative Liability, Current		(3,797)		(4,907)
Derivative Liability, Noncurrent		(1,761)		(1,673)
Total mark-to-market derivative liabilities		(5,558)		(6,580)
Exelon Generation Co L L C [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Current assets collateral offset		159		352
Noncurrent assets collateral offset		88		180
Current liabilities collateral offset		170		480
Noncurrent liabilities collateral offset		104		222
Total cash collateral received net of cash collateral posted		521		(1,234)
Exelon Generation Co L L C [Member] | Derivative [Member]
Derivative [Line Items]
Derivative Asset, Current	[1]	750		1,350
Derivative Asset, Noncurrent	[1]	492		719
Total mark-to-market derivative net assets (liabilities)	[1]	894		1,753
Total mark-to-market derivative assets	[1]	1,242		2,069
Derivative Liability, Current	[1]	(125)		(174)
Derivative Liability, Noncurrent	[1]	(223)		(142)
Total mark-to-market derivative liabilities	[1]	(348)		(316)
Exelon Generation Co L L C [Member] | Proprietary Trading [Member]
Derivative [Line Items]
Derivative Asset, Current		99		108
Derivative Asset, Noncurrent		28		22
Total mark-to-market derivative net assets (liabilities)		(4)		3
Total mark-to-market derivative assets		127		130
Derivative Liability, Current		(94)		(94)
Derivative Liability, Noncurrent		(37)		(33)
Total mark-to-market derivative liabilities		(131)		(127)
Exelon Generation Co L L C [Member] | Collateral And Netting [Member]
Derivative [Line Items]
Derivative Asset, Current		(3,438)		(3,994)
Derivative Asset, Noncurrent		(1,382)		(1,163)
Total mark-to-market derivative net assets (liabilities)	[2]	521		1,234
Total mark-to-market derivative assets	[2]	(4,820)		(5,157)
Derivative Liability, Current		3,766		4,827
Derivative Liability, Noncurrent		1,575		1,564
Total mark-to-market derivative liabilities	[2]	5,341		6,391
Commonwealth Edison Co [Member]
Derivative [Line Items]
Derivative Liability, Current		(18)		(23)
Derivative Liability, Noncurrent		(203)		(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]	(221)		(247)
Total mark-to-market derivative assets	[3]	0		0
Derivative Liability, Current		18		(23)
Derivative Liability, Noncurrent		203		(224)
Total mark-to-market derivative liabilities	[3]	(221)		(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				6 Months Ended
		Jun. 30, 2016		Jun. 30, 2015		Jun. 30, 2016		Jun. 30, 2015		Mar. 31, 2016	Dec. 31, 2015		Mar. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	$ (2,565)		$ (2,626)		$ (2,565)		$ (2,626)			$ (2,624)			$ (2,684)
OCI before reclassifications	[1]					(7)		(48)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1],[2]					(66)		(106)
Income taxes		102		327		285		690
Effect of Hedges on Accumulated Other Comprehensive Income [Roll Forward]
Reclassifications from accumulated OCI to net income		3,234		4,080		7,708		9,714
Exelon Generation Co L L C [Member]
Derivative [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	(65)		(47)		(65)		(47)			(63)			(36)
OCI before reclassifications	[1]					1		(14)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1],[2]					3		(3)
Income taxes		(31)		181		120		407
Effect of Hedges on Accumulated Other Comprehensive Income [Roll Forward]
Reclassifications from accumulated OCI to net income		3,231		4,079		7,702		9,709
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Derivative [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	(26)		(19)		(26)		(19)						(28)
OCI before reclassifications	[1]							(10)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1],[2]							(19)
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		(26)	[1]	(19)	[1]	(26)	[1]	(19)	[1]	$ (26)	(19)	[1]	$ (22)	(28)
OCI before reclassifications				1		(4)	[1]
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		(25)	[1]	(21)	[1]	(25)	[1]	(21)	[1]					(18)
OCI before reclassifications	[1]							(6)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1],[2]							(3)
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		(25)	[1]	(21)	[1]	(25)	[1]	(21)	[1]		$ (21)			$ (18)
OCI before reclassifications				0		(1)	[1]
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		(25)	[1]	(21)	[1]	(25)	[1]	(21)	[1]	$ (26)			$ (23)
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]			0		2		(10)
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				0	[3]	2	[3]	0
Interest Expense [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Effect of Hedges on Accumulated Other Comprehensive Income [Roll Forward]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion				(2)
Interest Expense [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1],[2]					3
Effect of Hedges on Accumulated Other Comprehensive Income [Roll Forward]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion		0		2				5
Interest Expense [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Exelon Generation Co L L C [Member]
Effect of Hedges on Accumulated Other Comprehensive Income [Roll Forward]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion				(2)
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]
Derivative [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1],[2]					$ 3
Effect of Hedges on Accumulated Other Comprehensive Income [Roll Forward]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion		$ 1		$ 2				5
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								(10)
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								(6)
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. 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		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Derivative [Line Items]
Unrealized Gain (Loss) on Commodity Contracts	$ (197)	$ 307	$ (44)	$ 392
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(105)	(67)	(149)	(1)
Unrealized Gain (Loss) on Derivatives			(194)	507
Change in Unrealized Gain (Loss) on Hedged Item in Foreign Currency Fair Value Hedge	1	111	(4)	46
Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Commodity Contracts	(197)	307	(44)	392
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(105)	(67)	(149)	(1)
Unrealized Gain (Loss) on Derivatives			(199)	396
Change in Unrealized Gain (Loss) on Hedged Item in Foreign Currency Fair Value Hedge	1	(3)	(4)	10
Purchased Power And Fuel [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Commodity Contracts	235	110	109	15
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	76	100	243	203
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		0
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		0		0
Change in Unrealized Gain (Loss) on Hedged Item in Foreign Currency Fair Value Hedge		114		36
Operating Revenue [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Commodity Contracts	(432)	197	(153)	377
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(181)	(167)	(392)	(204)
Change in Unrealized Gain (Loss) on Hedged Item in Foreign Currency Fair Value Hedge	1	(3)	(4)	10
Operating Revenue [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	(1)	(2)	2	1
Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(3)	62	(4)	60
Unrealized Gain (Loss) on Derivatives	(2)	173	(8)	106
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	(304)	413	(201)	497
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	(3)	(2)	(4)	(4)
Unrealized Gain (Loss) on Derivatives	(2)	(5)	(8)	6
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	(304)	235	(201)	397
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	311	210	352	218
Foreign Exchange Contract [Member] | Interest Expense [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		64		64
Unrealized Gain (Loss) on Derivatives		178		100
Unrealized Gain (Loss) on Derivatives and Commodity Contracts		178		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	(3)	(2)	(4)	(4)
Unrealized Gain (Loss) on Derivatives	(2)	(5)	(8)	6
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	(615)	25	(553)	179
Foreign Exchange Contract [Member] | Operating Revenue [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(1)	(2)	1	(6)
Unrealized Gain (Loss) on Derivatives	(1)	(2)	(1)	(2)
Change in Unrealized Gain (Loss) on Hedged Item in Foreign Currency Fair Value Hedge	0	0	(2)	4
Commodity Contract [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	(302)	240	(193)	391
Commodity Contract [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	(302)	240	(193)	391
Commodity Contract [Member] | Purchased Power And Fuel [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	311	210	352	218
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	(613)	30	(545)	173
Commodity Contract [Member] | Operating Revenue [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Commodity Contracts	5	7	14	8
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(5)	(7)	(11)	(5)
Unrealized Gain (Loss) on Derivatives	$ 0	$ 0	$ 3	$ 3

Derivative Financial Instrume78

Derivative Financial Instruments - Summary of Proprietary Trading Activities (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Derivative [Line Items]
Unrealized Gain (Loss) on Commodity Contracts	$ (197)	$ 307	$ (44)	$ 392
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(105)	(67)	(149)	(1)
Unrealized Gain (Loss) on Derivatives			(194)	507
Change in Unrealized Gain (Loss) on Hedged Item in Foreign Currency Fair Value Hedge	1	111	(4)	46
Operating Revenue [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	(1)	(2)	2	1
Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Commodity Contracts	(197)	307	(44)	392
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(105)	(67)	(149)	(1)
Unrealized Gain (Loss) on Derivatives			(199)	396
Change in Unrealized Gain (Loss) on Hedged Item in Foreign Currency Fair Value Hedge	1	(3)	(4)	10
Commodity Contract [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	(302)	240	(193)	391
Commodity Contract [Member] | Operating Revenue [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Commodity Contracts	5	7	14	8
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(5)	(7)	(11)	(5)
Unrealized Gain (Loss) on Derivatives	0	0	3	3
Commodity Contract [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives	(302)	240	(193)	391
Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(3)	62	(4)	60
Unrealized Gain (Loss) on Derivatives	(2)	173	(8)	106
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	(304)	413	(201)	497
Foreign Exchange Contract [Member] | Operating Revenue [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(1)	(2)	1	(6)
Unrealized Gain (Loss) on Derivatives	(1)	(2)	(1)	(2)
Change in Unrealized Gain (Loss) on Hedged Item in Foreign Currency Fair Value Hedge	0	0	(2)	4
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	(3)	(2)	(4)	(4)
Unrealized Gain (Loss) on Derivatives	(2)	(5)	(8)	6
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	$ (304)	$ 235	$ (201)	$ 397

Derivative Financial Instrume79

Derivative Financial Instruments - Summary of Credit Risk Exposure (Details) - Exelon Generation Co L L C [Member] $ in Millions	Jun. 30, 2016USD ($)
Derivative [Line Items]
Investor-owned utilities, marketers and power producers	$ 573
Energy Cooperatives And Municipalities	696
Financial institutions	96
Other	30
Net Exposure [Member]
Derivative [Line Items]
Investment grade	953
Non-investment grade	31
No external ratings - internally rated - investment grade	372
No external ratings - internally rated - non-investment grade	39
Total	1,395
Total Exposure Before Credit Collateral [Member]
Derivative [Line Items]
Investment grade	965
Non-investment grade	55
No external ratings - internally rated - investment grade	373
No external ratings - internally rated - non-investment grade	46
Total	1,439
Credit Collateral [Member]
Derivative [Line Items]
Investment grade	12
Non-investment grade	24
No external ratings - internally rated - investment grade	1
No external ratings - internally rated - non-investment grade	7
Total	44	[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	356
Non-investment grade	0
No external ratings - internally rated - investment grade	0
No external ratings - internally rated - non-investment grade	0
Total	$ 356
[1]	of June 30, 2016, credit collateral held from counterparties where Generation had credit exposure included $9 million of cash and $35 million of letters of credit.

Derivative Financial Instrume80

Derivative Financial Instruments - Summary of Credit Risk Related Contingent Features (Details) - Exelon Generation Co L L C [Member] - USD ($) $ in Millions		Jun. 30, 2016	Dec. 31, 2015
Derivative [Line Items]
Aggregate fair value of derivatives with credit-risk-related contingent features		$ (912)	$ (932)
Contractual right of offset related to derivative assets		657	684
Net liability position after contractual right of offset	[1]	$ (255)	$ (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			6 Months Ended			12 Months Ended
		Jun. 30, 2016USD ($)GWh	Jun. 30, 2015USD ($)GWh		Jun. 30, 2016USD ($)GWh		Jun. 30, 2015USD ($)GWh	Dec. 31, 2014USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Derivative [Line Items]
Income taxes		$ 102	$ 327		$ 285		$ 690
Derivative, Notional Amount		100			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					3
Ineffective portion recognized in income	[1]	4			6
Mark-to-market derivative liabilities (noncurrent liabilities)		442			442					$ 374
Derivative Liability, Current		152			152					205
Cash collateral posted		9			9
Letters of credit posted		35			35
Interest Rate Fair Value Hedge Asset at Fair Value		39			39
Debt Instrument, Face Amount			750				750
Exelon Generation Co L L C [Member]
Derivative [Line Items]
Income taxes		(31)	$ 181		120		$ 407
Mark-to-market derivative liabilities (noncurrent liabilities)		237			237					150
Derivative Liability, Current		134			134					182
Cash collateral received not offset against net derivative positions		10			10					3
Cash collateral posted		548			548					1,267
Letters of credit held		46			46					78
Letters of credit posted		441			441					497
Cash collateral held		14			14					21
Incremental collateral for loss of investment grade credit rating		1,800			1,800					2,000
Interest Rate Fair Value Hedge Asset at Fair Value		$ (7)			$ (7)
Derivative, Nonmonetary Notional Amount, Energy Measure | GWh		1,289	1,657		2,509		3,465
Debt Instrument, Face Amount		$ 10			$ 10
Commonwealth Edison Co [Member]
Derivative [Line Items]
Income taxes		91	$ 68		168		$ 127
Mark-to-market derivative liabilities (noncurrent liabilities)		203			203					224
Derivative Liability, Current		18			18					23
Cash collateral held		19			19
Incremental collateral for loss of investment grade credit rating		3			3
Credit Exposure Under Off System Sales		1			1
PECO Energy Co [Member]
Derivative [Line Items]
Income taxes		23	27		$ 67		85
Estimated percentage of natural gas purchases hedged					30.00%
Incremental collateral for loss of investment grade credit rating		26			$ 26
Baltimore Gas and Electric Company [Member]
Derivative [Line Items]
Income taxes		6	32		73		105
Incremental collateral for loss of investment grade credit rating		31			31
Credit Exposure Under Off System Sales		1			1
Delmarva Power and Light Company [Member]
Derivative [Line Items]
Income taxes		8	5		(1)		26
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					97.00%
Expected Generation Hedged In Year Two					78.00%
Expected generation hedged in year three					47.00%
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					100.00%
Expected Generation Hedged In Year Two					81.00%
Expected generation hedged in year three					50.00%
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		4			4
Cash Flow Hedging [Member]
Derivative [Line Items]
Derivative, Notional Amount		100			100
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional Amount of Pre-issuance Interest Rate Cash Flow Hedge Derivatives		764			764
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		674			674
Designated as Hedging Instrument [Member] | Commonwealth Edison Co [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	[2]	(221)			(221)					(247)
Mark-to-market derivative liabilities (noncurrent liabilities)		(203)			(203)					224
Derivative Liability, Current		(18)			(18)					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		100			100
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		673			673					1,506
Mark-to-market derivative liabilities (noncurrent liabilities)		426			426					366
Derivative Liability, Current		143			143					197
Derivative [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	[3]	894			894					1,753
Mark-to-market derivative liabilities (noncurrent liabilities)	[3]	223			223					142
Derivative Liability, Current	[3]	125			125					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					47			$ 25
Cash Flow Hedging [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount		90			90
Increase (Decrease) in Fair Value of Interest Rate Fair Value Hedging Instruments					1
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					177
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				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		497			497
ExGen Texas Power [Member] | Cash Flow Hedging [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Mark-to-market derivative liabilities (noncurrent liabilities)		18			18
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]		0		2		(10)
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			$ 0	[5]	2	[5]	$ 0
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)
Commonwealth Edison Co Affiliate [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Net receivable from electric utility		26			26
PECO Energy Co Affiliate [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Net receivable from affiliated electric and gas utility		40			40
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		36			36
Potomac Electric Power Company [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Net receivable from electric utility		50			50
Delmarva Power and Light Company [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Net receivable from electric utility		15			15
Atlantic City Electric Company [Member] | Exelon Generation Co L L C [Member]
Derivative [Line Items]
Net receivable from electric utility		$ 8			$ 8
[1]	For the six months ended June 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	Jun. 30, 2016	Dec. 31, 2015
Commonwealth Edison Co [Member]
Short-term Debt [Line Items]
Commercial paper borrowings	$ 35	$ 294
Baltimore Gas and Electric Company [Member]
Short-term Debt [Line Items]
Commercial paper borrowings	208	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	0	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	Jun. 30, 2016	Apr. 01, 2016	Mar. 31, 2016	Jan. 13, 2016	Dec. 31, 2015	Jun. 30, 2015
Debt Instrument [Line Items]
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]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		10
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
Short-term Debt, Percentage Bearing Variable Interest Rate					1.00%
Repayments of Bank Debt		300
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	Jun. 30, 2016	Jun. 30, 2015
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 750
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]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 10
Exelon Generation Co L L C [Member] | Energy Efficiency Project Financing [Member]
Debt Instrument [Line Items]
Interest Rate	1.43%
Debt Instrument, Face Amount	$ 63
Exelon Generation Co L L C [Member] | EscoNotes390February2018 [Member]
Debt Instrument [Line Items]
Interest Rate	3.90%
Debt Instrument, Face Amount	$ 7
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] | DOE Financing Project [Member] | Energy Efficiency Project Financing [Member]
Debt Instrument [Line Items]
Interest Rate	4.11%
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
Potomac Electric Power Company [Member] | EscoNotes330August2017 [Member]
Debt Instrument [Line Items]
Interest Rate	3.30%
Debt Instrument, Face Amount	$ 1

Income Taxes - Reconciliation t

Income Taxes - Reconciliation to Effective Tax Rate (Details)	Mar. 31, 2016	Jun. 30, 2016	Mar. 23, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Increase (decrease) due to:
U.S. Federal statutory rate		35.00%		35.00%	35.00%	35.00%
State income taxes, net of Federal income tax benefit(b)		(2.30%)		(3.90%)	(0.80%)	(3.20%)
Domestic production activities deduction		(0.00%)		2.00%	(0.00%)	2.10%
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		1.80%		0.60%	1.70%	0.80%
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent		(6.90%)		(1.00%)	(6.30%)	(1.10%)
Production tax credits and other credits		(5.70%)		1.00%	(5.60%)	(0.60%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent		(5.80%)		(1.30%)	(5.50%)	(1.60%)
Noncontrolling interests		0.90%		(0.40%)	0.70%	(0.60%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent		(1.70%)			(1.00%)
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Percent		0.20%			14.50%
Other(c)		3.30%		(1.40%)	2.80%	(0.80%)
Effective income tax rate		24.60%		34.00%	39.30%	33.40%
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%
State income taxes, net of Federal income tax benefit(b)		116.70%		(3.40%)	(2.60%)	(3.00%)
Domestic production activities deduction		(0.00%)		3.40%	(0.00%)	3.40%
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		157.80%		0.90%	2.50%	1.10%
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent		0.00%		0.00%	0.00%	0.00%
Production tax credits and other credits		(591.20%)		1.70%	(9.80%)	(0.90%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent		(603.00%)		(2.20%)	(9.60%)	(2.50%)
Noncontrolling interests		94.40%		(0.60%)	1.20%	(0.80%)
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent		(410.80%)			(3.90%)
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Percent		0.00%			0.00%
Other(c)		52.30%		(2.00%)	3.80%	(0.60%)
Effective income tax rate		(620.00%)		31.60%	28.80%	31.70%
Commonwealth Edison Co [Member]
Increase (decrease) due to:
U.S. Federal statutory rate		35.00%		35.00%	35.00%	35.00%
State income taxes, net of Federal income tax benefit(b)		(4.80%)		(5.60%)	(4.90%)	(5.30%)
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		0.20%		0.30%	0.20%	0.30%
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent		(0.40%)		(0.10%)	(0.30%)	(0.20%)
Production tax credits and other credits		(0.00%)		(0.00%)	(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%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Percent		0.00%			0.00%
Other(c)		0.60%		(0.50%)	0.10%	(0.40%)
Effective income tax rate		38.60%		40.70%	39.30%	40.20%
PECO Energy Co [Member]
Increase (decrease) due to:
U.S. Federal statutory rate		35.00%		35.00%	35.00%	35.00%
State income taxes, net of Federal income tax benefit(b)		(0.30%)		(1.40%)	(0.70%)	(1.30%)
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		(11.30%)		(9.00%)	(10.20%)	(7.50%)
Production tax credits and other credits		(0.00%)		(0.00%)	(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%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Percent		0.00%			0.00%
Other(c)		5.20%		(0.50%)	2.40%	(0.20%)
Effective income tax rate		18.70%		27.80%	23.00%	28.90%
Baltimore Gas and Electric Company [Member]
Increase (decrease) due to:
U.S. Federal statutory rate		35.00%		35.00%	35.00%	35.00%
State income taxes, net of Federal income tax benefit(b)		(2.00%)		(5.30%)	(4.60%)	(5.30%)
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%		0.10%	0.00%	0.20%
Amortization of investment tax credit, including deferred taxes on basis difference		0.40%		0.20%	0.10%	0.10%
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent		(20.60%)		(0.50%)	(4.50%)	(0.30%)
Production tax credits and other credits		(0.00%)		(0.00%)	(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%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Percent		0.00%			0.00%
Other(c)		1.00%		(0.80%)	(0.10%)	(0.00%)
Effective income tax rate		15.00%		40.50%	35.10%	40.10%
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%
State income taxes, net of Federal income tax benefit(b)				(5.30%)		(6.40%)
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				0.30%		0.40%
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent				(7.30%)		(6.10%)
Production tax credits and other credits				(0.00%)		(0.00%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent				0.00%		0.00%
Noncontrolling interests						0.00%
Other(c)				(1.10%)		0.30%
Effective income tax rate				33.80%		34.60%
Pepco Holdings LLC [Member] | Successor [Member]
Increase (decrease) due to:
U.S. Federal statutory rate		35.00%
State income taxes, net of Federal income tax benefit(b)		(6.10%)
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		0.30%
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent		(7.00%)
Production tax credits and other credits		(0.00%)
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%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Percent		1.00%
Other(c)		(1.00%)
Effective income tax rate		35.80%
Delmarva Power and Light Company [Member]
Increase (decrease) due to:
U.S. Federal statutory rate		35.00%		35.00%	35.00%	35.00%
State income taxes, net of Federal income tax benefit(b)		(4.80%)		(5.00%)	5.20%	(5.50%)
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		0.60%		1.00%	(0.40%)	0.40%
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent		(3.50%)		(4.20%)	2.00%	(1.50%)
Production tax credits and other credits		(0.00%)		(0.00%)	(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%
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent		0.00%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Percent		3.10%			(30.50%)
Other(c)		(1.20%)		(3.70%)	0.10%	(0.80%)
Effective income tax rate		40.00%		38.50%	1.60%	39.40%
Potomac Electric Power Company [Member]
Increase (decrease) due to:
U.S. Federal statutory rate		35.00%		35.00%	35.00%	35.00%
State income taxes, net of Federal income tax benefit(b)		(3.50%)		(5.00%)	9.50%	(4.10%)
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		0.10%		(0.00%)	(0.10%)	(0.00%)
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent		(5.70%)		(8.30%)	12.60%	(8.20%)
Production tax credits and other credits		(0.00%)		(0.00%)	(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%
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent		0.00%			0.00%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Percent		0.20%			(36.10%)
Other(c)		1.00%		1.70%	0.50%	0.30%
Effective income tax rate		31.90%		30.00%	1.60%	30.60%
Atlantic City Electric Company [Member]
Increase (decrease) due to:
U.S. Federal statutory rate		35.00%		35.00%	35.00%	35.00%
State income taxes, net of Federal income tax benefit(b)		(5.90%)		(9.90%)	(5.90%)	(5.50%)
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		1.60%		0.20%	(0.10%)	0.90%
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent		(7.10%)		(0.10%)	1.00%	(1.70%)
Production tax credits and other credits		(0.00%)		(0.00%)	(0.00%)	(0.00%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent				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, Nondeductible Expense, Other, Percent					(17.70%)
Other(c)		(7.80%)		4.60%	0.10%	0.40%
Effective income tax rate		40.00%		40.00%	24.20%	37.50%
Atlantic City Electric Company [Member] | Successor [Member]
Increase (decrease) due to:
U.S. Federal statutory rate	35.00%		35.00%
State income taxes, net of Federal income tax benefit(b)	(5.20%)		(11.90%)
Domestic production activities deduction	(0.00%)		(0.00%)
Amortization of investment tax credit, including deferred taxes on basis difference	(0.10%)		0.90%
Effective Income Tax Rate Reconciliation,Other Reconciling Items, Percent	1.70%		(13.50%)
Production tax credits and other credits	(0.00%)		(0.00%)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent	0.00%		0.00%
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent	0.00%		0.00%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Percent	(18.90%)		11.10%
Other(c)	(0.00%)		(3.60%)
Effective income tax rate	23.10%		47.20%

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended			6 Months Ended
	Sep. 30, 2014	Jun. 30, 2016	Jun. 30, 2015	Mar. 31, 2014	Jun. 30, 2016	Dec. 31, 2015	Dec. 31, 2009
Income Tax Additional Narrative Information [Line Items]
Unrecognized Tax Benefits		$ (963)			$ (963)	$ (1,101)
Unrecognized Tax Benefits, Period Increase (Decrease)		328			190
Unrecognized tax benefits that if recognized would affect the effective tax rate		75			75
Increase (Decrease) in Income Taxes					300
Deferred tax gain under involuntary conversion provisions of the IRC							$ 1,200
IRS asserted penalties for understatement of tax					90
Expected non-cash charge to earnings				$ 265
Potential tax and interest from a successful IRS challenge of the like-kind exchange transaction position		460			460
Early termination amount			$ 335
Taxes Payable, Current			360
Tax Adjustments, Settlements, and Unusual Provisions					310
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		(531)			(531)	(534)
Increase (Decrease) in Income Taxes	$ 67
Effective Income Tax Rate Reconciliation, Tax Settlement, Amount		120
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
Unrecognized tax benefits that if recognized would affect the effective tax rate		12			12
Expected non-cash charge to earnings				172
Non-cash equity contributions				$ 172
Potential tax and interest from a successful IRS challenge of the like-kind exchange transaction position		275			275
Taxes Payable, Current			$ 65
Tax Adjustments, Settlements, and Unusual Provisions					12
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)
Pepco Holdings LLC [Member]
Income Tax Additional Narrative Information [Line Items]
Unrecognized Tax Benefits		(181)			(181)
Unrecognized Tax Benefits, Period Increase (Decrease)		159
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		(95)			(95)	(8)
Unrecognized Tax Benefits, Period Increase (Decrease)		87
Increase (Decrease) in Income Taxes	71
Delmarva Power and Light Company [Member]
Income Tax Additional Narrative Information [Line Items]
Unrecognized Tax Benefits		(39)			(39)	(3)
Unrecognized Tax Benefits, Period Increase (Decrease)		36
Increase (Decrease) in Income Taxes	$ 20
Atlantic City Electric Company [Member]
Income Tax Additional Narrative Information [Line Items]
Unrecognized Tax Benefits		(24)			$ (24)	$ 0
Unrecognized Tax Benefits, Period Increase (Decrease)		$ 24

Income Taxes Income Tax Unrecog

Income Taxes Income Tax Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$ 963	$ 1,101
Exelon Generation Co L L C [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	531	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	181
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	39	3
Potomac Electric Power Company [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	95	8
Atlantic City Electric Company [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$ 24	$ 0

Nuclear Decommissioning - Rollf

Nuclear Decommissioning - Rollforward of Nuclear Decommissioning ARO (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation, Accretion Expense	[1]	$ 220	$ 193
Exelon Generation Co L L C [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation, Accretion Expense	[1]	220	$ 193
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		215
Asset Retirement Obligation, Liabilities Settled		(2)
Asset Retirement Obligation, Period Increase (Decrease)		657
Asset Retirement Obligation, Revision of Estimate		444
Nuclear Decommissioning ARO, Ending Balance	[2]	8,903
Current portion of ARO		$ 11
[1]	Included in Operating and maintenance expense on the Registrants’ Consolidated Statements of Operations and Comprehensive Income
[2]	Includes $11 million and $7 million for the current portion of the ARO at June 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	Jun. 30, 2016	Dec. 31, 2015
Nuclear Decommissioning Additional Narrative Information [Line Items]
Decommissioning Liability, Noncurrent	$ 54	$ 90
Decommissioning Fund Investments	10,737	10,342
Exelon Generation Co L L C [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Decommissioning Liability, Noncurrent	54	90
Decommissioning Fund Investments	10,737	$ 10,342
Nuclear Plant [Member] | Exelon Generation Co L L C [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Decommissioning Liability, Noncurrent	$ 86

Nuclear Decommissioning - Unrea

Nuclear Decommissioning - Unrealized Gains on NDT Funds (Details) - Exelon Generation Co L L C [Member] - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Unrealized Losses On Nuclear Decommissioning Trust Fund Investment [Line Items]
Net unrealized gains (losses) on decommissioning trust funds - regulatory agreement units	[1]	$ 52	$ (133)	$ 131	$ (85)
Net unrealized gains (losses) on decommissioning trust funds - non-regulatory agreement units	[2],[3]	48	$ (96)	100	(56)
Unrealized Gain Loss Investment Income Pledged Assets		$ 1		$ 3	$ (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 $1 million of net unrealized gain related to the Zion Station pledged assets for the three months ended June 30, 2016. Excludes $3 million and $9 million of net unrealized gain related to the Zion Station pledged assets for the six months ended June 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		6 Months Ended	12 Months Ended
		Jun. 30, 2016	Dec. 31, 2015
Nuclear Decommissioning Additional Narrative Information [Line Items]
Pledged assets for Zion Station decommissioning		$ 161	$ 206
Exelon Generation Co L L C [Member]
Nuclear Decommissioning Additional Narrative Information [Line Items]
Pledged assets for Zion Station decommissioning		161	206
Payable to Zion Solutions	[1]	148	189
Current portion of payable to Zion Solutions	[2]	94	99
Withdrawals by Zion Solutions to pay decommissioning costs	[3]	$ 834	$ 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	6 Months Ended
	Mar. 31, 2016	Jun. 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
Pension Obligations Valuation Adjustment	35
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]
Pension Obligations Valuation Adjustment		$ 25
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
		Jun. 30, 2016		Jun. 30, 2016	Mar. 23, 2016	Jun. 30, 2015		Jun. 30, 2016		Jun. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions		$ 30				$ 38		$ 56		$ 60
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		91				81		170	[1]	163
Interest cost		212				178		403	[1]	355
Expected return on assets		(292)				(256)		(555)	[1]	(513)
Amortization of:
Prior service cost (benefit)		4				4		7	[1]	7
Defined Benefit Plan, Actuarial Gain (Loss)		142				142		269	[1]	285
Net periodic benefit cost		157				149		294	[1]	297
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		28				29		54	[1]	59
Interest cost		48				42		90	[1]	83
Expected return on assets		(42)				(37)		(80)	[1]	(75)
Amortization of:
Prior service cost (benefit)		(47)				(44)		(91)	[1]	(88)
Defined Benefit Plan, Actuarial Gain (Loss)		16				21		30	[1]	41
Net periodic benefit cost		3				11		3	[1]	20
Potomac Electric Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions		1	[2]		$ 1	1	[2]	2	[2]	2	[2]
Amortization of:
Pension and Other Postretirement Benefit Costs					7
Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions				$ 4				4
Pepco Holdings LLC [Member] | Predecessor [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions					3	4				7
Pepco Holdings LLC [Member] | Pension Plan, Defined Benefit [Member] | Predecessor [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost					12	14				28
Interest cost					26	27				54
Expected return on assets					(30)	(35)				(70)
Amortization of:
Prior service cost (benefit)					0	1				1
Defined Benefit Plan, Actuarial Gain (Loss)					14	17				33
Net periodic benefit cost					22	24				46
Pepco Holdings LLC [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member] | Predecessor [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost					1	1				3
Interest cost					6	6				12
Expected return on assets					(5)	(5)				(11)
Amortization of:
Prior service cost (benefit)					(3)	(3)				(6)
Defined Benefit Plan, Actuarial Gain (Loss)					2	1				4
Net periodic benefit cost					1	0				2
Delmarva Power and Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions		0	[2]		1	1	[2]	1	[2]	1	[2]
Amortization of:
Pension and Other Postretirement Benefit Costs					4
Atlantic City Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions	[2]	1				1		1		1
Amortization of:
Pension and Other Postretirement Benefit Costs					3
Corporate, Non-Segment [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions	[2],[3]	$ 2
Corporate, Non-Segment [Member] | Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions	[2],[3]				1	$ 1		$ 3		$ 3
Amortization of:
Pension and Other Postretirement Benefit Costs					$ 9
[1]	(a)PHI net periodic benefit costs for the period prior to the merger are not included in the table above.
[2]	Pepco's, DPL's and PHISCO's matching contributions for the six months ended June 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 six months ended June 30, 2016.
[3]	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.

Retirement Benefits - Allocated

Retirement Benefits - Allocated Portion of Pension and Postretirement Benefit Plan Costs (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2016	Jun. 30, 2016	Mar. 23, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense		$ 160			$ 160	$ 297	$ 317
Corporate, Non-Segment [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense	[1]	10			14	24	29
Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense		27	$ 31
Pepco Holdings LLC [Member] | Corporate, Non-Segment [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense	[1],[2]	12			9	21	17
Exelon Generation Co L L C [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense		55			68	109	133
Commonwealth Edison Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense		42			51	83	103
PECO Energy Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense		8			10	17	19
Baltimore Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense		18			17	33	33
Potomac Electric Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense	[2]	7			7	16	15
Delmarva Power and Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense	[2]	4			4	9	8
Atlantic City Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense	[2]	$ 4			4	$ 8	8
Predecessor [Member] | Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefit Expense				$ 23	$ 24		$ 48
[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 six months ended June 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
		Jun. 30, 2016		Jun. 30, 2016	Mar. 23, 2016	Jun. 30, 2015		Jun. 30, 2016		Jun. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions		$ 30				$ 38		$ 56		$ 60
Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions				$ 4				4
Exelon Generation Co L L C [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions		13				20		25		33
Commonwealth Edison Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions		7				8		13		13
PECO Energy Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions		2				3		4		4
Baltimore Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions		2				3		3		5
Business Services Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions	[1]	2				4		7		5
Potomac Electric Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions		1	[2]		$ 1	1	[2]	2	[2]	2	[2]
Delmarva Power and Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions		0	[2]		1	1	[2]	1	[2]	1	[2]
Atlantic City Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions	[2]	1				1		1		1
Predecessor [Member] | Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions					3	4				7
Corporate, Non-Segment [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions	[1],[2]	$ 2
Corporate, Non-Segment [Member] | Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Matching Contributions	[1],[2]				$ 1	$ 1		$ 3		$ 3
[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 six months ended June 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 six months ended June 30, 2016.

Severance - Narrative (Details)

Severance - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Restructuring Cost and Reserve [Line Items]
Severance Costs	$ 2	$ 1	$ 4	$ 21
Exelon Generation Co L L C [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	1	1	3	21
Exelon Generation Co L L C [Member] | Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	46
Exelon Generation Co L L C [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	1	$ 2	$ 2	$ 4
Exelon Generation Co L L C [Member] | Corporate, Non-Segment [Member] | Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	$ 3

Severance - Ongoing Severance P

Severance - Ongoing Severance Plans (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	$ 2	$ 1	$ 4	$ 21
Exelon Generation Co L L C [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	1	1	3	21
Exelon Generation Co L L C [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	1	2	2	4
Commonwealth Edison Co [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	$ 1	$ 0	1	$ 0
Commonwealth Edison Co [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs			$ 1

Severance - PHI Merger (Details

Severance - PHI Merger (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	$ 2	$ 1	$ 4	$ 21
PHI Merger [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	2		55
Exelon Generation Co L L C [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	1	1	3	21
Exelon Generation Co L L C [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	1	2	2	4
Exelon Generation Co L L C [Member] | PHI Merger [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	(1)		9
Exelon Generation Co L L C [Member] | PHI Merger [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	(1)		8
Commonwealth Edison Co [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	1	$ 0	1	$ 0
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	(1)		2
Commonwealth Edison Co [Member] | PHI Merger [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	(1)		2
PECO Energy Co [Member] | PHI Merger [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	0		1
PECO Energy Co [Member] | PHI Merger [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	1		1
Baltimore Gas and Electric Company [Member] | PHI Merger [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	0		1
Baltimore Gas and Electric Company [Member] | PHI Merger [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	1		1
Pepco Holdings LLC [Member] | PHI Merger [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	4		42
Pepco Holdings LLC [Member] | PHI Merger [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	2		19
Potomac Electric Power Company [Member] | PHI Merger [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	2		20
Delmarva Power and Light Company [Member] | PHI Merger [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	1		12
Delmarva Power and Light Company [Member] | PHI Merger [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	1		11
Atlantic City Electric Company [Member] | PHI Merger [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	1		10
Atlantic City Electric Company [Member] | PHI Merger [Member] | Corporate, Non-Segment [Member]
Corporate Restructuring Severance Benefit Obligation [Line Items]
Severance Costs	$ 1		$ 10

Severance - Severance Liabiliti

Severance - Severance Liabilities (Details) $ in Millions	6 Months Ended
	Jun. 30, 2016USD ($)
Restructuring Reserve [Roll Forward]
Beginning Balance	$ 35
Severance Charges Expense	(129)
Payments for Restructuring	(19)
Ending Balance	145
Exelon Generation Co L L C [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	23
Severance Charges Expense	(56)
Payments for Restructuring	(4)
Ending Balance	75
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	0
Ending Balance	1
Pepco Holdings LLC [Member]
Restructuring Reserve [Roll Forward]
Ending Balance	43
Potomac Electric Power Company [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	0
Severance Charges Expense	(1)
Payments for Restructuring	0
Ending Balance	1
Delmarva Power and Light Company [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	0
Severance Charges Expense	(1)
Payments for Restructuring	0
Ending Balance	1
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	54
Payments for Restructuring	$ (11)

Severance Severance - Cost Mana

Severance Severance - Cost Management Program-Related (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Restructuring Cost and Reserve [Line Items]
Severance Costs	$ 2	$ 1	$ 4	$ 21
Cost Management Project [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs			17
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	1	1	3	21
Exelon Generation Co L L C [Member] | Cost Management Project [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs			12
Exelon Generation Co L L C [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	1	2	2	4
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	$ 1	$ 0	1	$ 0
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

Mezzanine Equity Mezzanine E101

Mezzanine Equity Mezzanine Equity (Details) - USD ($)	3 Months Ended	6 Months Ended
	Mar. 23, 2016	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Redeemable Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Common, Carrying Amount		$ 24,000,000		$ 28,000,000
Temporary Equity, Other Changes		$ 56,000,000
Preferred Stock, Shares Subscribed but Unissued, Value [Abstract]
Number of preferred shares purchased		18,000
Payments to Acquire Businesses, Gross		$ 6,642,000,000	$ 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		24,000,000		$ 28,000,000
Temporary Equity, Other Changes		(56,000,000)
Noncontrolling Interest, Increase from Sale of Parent Equity Interest		52,000,000
Preferred Stock, Shares Subscribed but Unissued, Value [Abstract]
Payments to Acquire Businesses, Gross		$ 1,000,000	$ 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				6 Months Ended
		Jun. 30, 2016		Jun. 30, 2015		Jun. 30, 2016		Jun. 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]	$ (2,565)		$ (2,626)		$ (2,565)		$ (2,626)		$ (2,624)		$ (2,684)
OCI before reclassifications	[1]					(7)		(48)
Amounts reclassified from AOCI	[1],[2]					66		106
Net current-period OCI		31		50		59	[1]	58	[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]	(26)		(19)		(26)		(19)				(28)
OCI before reclassifications	[1]							(10)
Amounts reclassified from AOCI	[1],[2]							19
Net current-period OCI	[1]					(7)		9
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]	(2,498)		(2,582)		(2,498)		(2,582)		(2,565)		(2,640)
OCI before reclassifications						(2)	[1]	(29)
Amounts reclassified from AOCI	[1],[2]					69		87
Net current-period OCI	[1]					67		58
Accumulated Translation Adjustment [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(34)	[1]	(28)	[1]	(34)	[1]	(28)	[1]	(40)	[1]	(19)
OCI before reclassifications	[1]					6		(9)
Net current-period OCI	[1]					6		(9)
Accumulated Equity Investment [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	(10)		0		(10)		0		(3)		0
OCI before reclassifications	[1]					(7)		0
Amounts reclassified from AOCI	[1],[2]					0		0
Net current-period OCI	[1]					(7)		0
Exelon Generation Co L L C [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	(65)		(47)		(65)		(47)		(63)		(36)
OCI before reclassifications	[1]					1		(14)
Amounts reclassified from AOCI	[1],[2]					(3)		3
Net current-period OCI		0		6		(2)	[1]	(11)	[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		(25)	[1]	(21)	[1]	(25)	[1]	(21)	[1]			(18)
OCI before reclassifications	[1]							(6)
Amounts reclassified from AOCI	[1],[2]							3
Net current-period OCI	[1]					(4)		(3)
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		1	[1]	2	[1]	1	[1]	2	[1]	1		1	[1]
OCI before reclassifications	[1]					0		1
Net current-period OCI	[1]					0		1
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		(34)	[1]	(28)	[1]	(34)	[1]	(28)	[1]	(40)	[1]	(19)
OCI before reclassifications	[1]					6		(9)
Net current-period OCI	[1]					6		(9)
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]	(7)		0		(7)		0		(3)		0
OCI before reclassifications	[1]					(4)		0
Amounts reclassified from AOCI	[1],[2]					0		0
Net current-period OCI	[1]					(4)		0
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]	(42)		(35)	[3]	(42)		(36)		(46)
OCI before reclassifications						0		0
Amounts reclassified from AOCI						1		4
Net current-period OCI						1		4
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]	(9)		(8)	[3]	(9)		(8)		(9)
OCI before reclassifications						0		0
Amounts reclassified from AOCI						0		0
Net current-period OCI						0		0
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. 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				6 Months Ended
		Jun. 30, 2016		Jun. 30, 2015		Jun. 30, 2016		Jun. 30, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues		$ 6,910		$ 6,514		$ 14,485		$ 15,345
Income before income taxes		415		962		725		2,064
Income taxes		(102)		(327)		(285)		(690)
Net income		306		633		430		1,372
Other, net		144		(17)		258		64
Equity in (losses) earnings of unconsolidated affiliates						(10)		(2)
Interest Expense		366		145		643		480
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income	[1]	(34)		(46)		(66)		(106)
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]			(2)		5		(29)
Income taxes	[1]			0		(2)		10
Net income	[1]			(2)		3		(19)
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
Interest Expense						5		(5)
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]	(56)		(71)		(113)		(142)
Income taxes		22	[1]	27	[1]	44	[1]	55
Net income	[1]	(34)		(44)		(69)		(87)
Prior service benefit reclassified to periodic benefit cost		19		19		38		38
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax	[1],[2]	(75)		(90)		(151)		(180)
Exelon Generation Co L L C [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues		3,589		4,232		8,329		10,074
Income before income taxes		5		573		416		1,285
Income taxes		31		(181)		(120)		(407)
Net income		28		390		285		875
Other, net		117		(31)		210		62
Equity in (losses) earnings of unconsolidated affiliates						(11)		(3)
Interest Expense		89		90		176		180
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]
Net income	[1]	0		(2)		3		(3)
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]			(2)		5		(3)
Income taxes				0	[1]	(2)	[1]	0
Net income	[1]			(2)		3		(3)
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		(5)
PEPCO Holdings Inc [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income				(3)		(1)		(4)
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				0		0		0
Income taxes				0		0		0
Net income				0		0		0
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		0		0
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				(3)		(1)		(5)
Income taxes				0		0		1
Net income				(3)		(1)		(4)
Prior service benefit reclassified to periodic benefit cost				0		0		0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax				(3)		(1)		(5)
Potomac Electric Power Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues		509		504		1,061		1,049
Income before income taxes		72		60		(61)		98
Income taxes		(23)		(18)		1		(30)
Net income		49		42		(60)		68
Other, net		6		8		14		13
Equity in (losses) earnings of unconsolidated affiliates						0		0
Interest Expense		31		31		68		61
Delmarva Power and Light Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues		281		271		643		691
Income before income taxes		20		13		(61)		66
Income taxes		(8)		(5)		1		(26)
Net income		12		8		(60)		40
Other, net		3		2		6		5
Equity in (losses) earnings of unconsolidated affiliates						0		0
Interest Expense		13		13		25		25
Atlantic City Electric Company [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Revenues		270		285		561		618
Income before income taxes		5		10		(128)		24
Income taxes		(2)		(4)		31		(9)
Net income		3		6		(97)		15
Other, net		2		1		5		3
Equity in (losses) earnings of unconsolidated affiliates						0		0
Interest Expense		$ 16		$ 16		$ 32		$ 32
[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		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016		Jun. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]			$ (7)		$ (48)
Pension and non-pension postretirement benefit plans:
Prior service benefit reclassified to periodic benefit cost		$ 7	$ 8	15		15
Actuarial loss reclassified to periodic cost		(30)	(35)	(60)		(69)
Pension and non-pension postretirement benefit plans valuation adjustment		0	0	1		17
Change in unrealized gain/(loss) on cash flow hedges		2	(2)	4		(6)
Change in unrealized loss on equity investments		1	0	3		0
Change in unrealized gain on marketable securities		(1)	1	0		1
Total		(21)	(28)	(37)		(42)
Other Comprehensive Income (Loss), Net of Tax		31	50	59	[1]	58	[1]
PEPCO Holdings Inc [Member]
Pension and non-pension postretirement benefit plans:
Actuarial loss reclassified to periodic cost			0			1
PEPCO Holdings Inc [Member] | Predecessor [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax				0		0
Pension and non-pension postretirement benefit plans:
Other Comprehensive Income (Loss), Net of Tax				1		4
Exelon Generation Co L L C [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]			1		(14)
Pension and non-pension postretirement benefit plans:
Change in unrealized gain/(loss) on cash flow hedges		1	(1)	3		1
Change in unrealized loss on equity investments		1	0	3		0
Change in unrealized gain on marketable securities		0	0	0		1
Total		2	(1)	6		2
Other Comprehensive Income (Loss), Net of Tax		$ 0	$ 6	(2)	[1]	(11)	[1]
PECO Energy Co [Member]
Pension and non-pension postretirement benefit plans:
Other Comprehensive Income (Loss), Net of Tax	[1]					0
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]					(10)
Pension and non-pension postretirement benefit plans:
Other Comprehensive Income (Loss), Net of Tax	[1]			(7)		9
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | PEPCO Holdings Inc [Member] | Predecessor [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax				0		0
Pension and non-pension postretirement benefit plans:
Other Comprehensive Income (Loss), Net of Tax				0		0
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Exelon Generation Co L L C [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]					(6)
Pension and non-pension postretirement benefit plans:
Other Comprehensive Income (Loss), Net of Tax	[1]			(4)		(3)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | PECO Energy Co [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]					0
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]			0		0
Pension and non-pension postretirement benefit plans:
Other Comprehensive Income (Loss), Net of Tax	[1]			0		0
Accumulated Net Unrealized Investment Gain (Loss) [Member] | PEPCO Holdings Inc [Member] | Predecessor [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax				0		0
Pension and non-pension postretirement benefit plans:
Other Comprehensive Income (Loss), Net of Tax				0		0
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Exelon Generation Co L L C [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]			0		1
Pension and non-pension postretirement benefit plans:
Other Comprehensive Income (Loss), Net of Tax	[1]			0		1
Accumulated Net Unrealized Investment Gain (Loss) [Member] | PECO Energy Co [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]					0
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax				(2)	[1]	(29)
Pension and non-pension postretirement benefit plans:
Other Comprehensive Income (Loss), Net of Tax	[1]			67		58
Accumulated Defined Benefit Plans Adjustment [Member] | PEPCO Holdings Inc [Member] | Predecessor [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax				0		0
Pension and non-pension postretirement benefit plans:
Other Comprehensive Income (Loss), Net of Tax				1		4
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]			6		(9)
Pension and non-pension postretirement benefit plans:
Other Comprehensive Income (Loss), Net of Tax	[1]			6		(9)
Accumulated Translation Adjustment [Member] | PEPCO Holdings Inc [Member] | Predecessor [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax				0		0
Pension and non-pension postretirement benefit plans:
Other Comprehensive Income (Loss), Net of Tax				0		0
Accumulated Translation Adjustment [Member] | Exelon Generation Co L L C [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]			6		(9)
Pension and non-pension postretirement benefit plans:
Other Comprehensive Income (Loss), Net of Tax	[1]			6		(9)
Accumulated Translation Adjustment [Member] | PECO Energy Co [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]					0
Accumulated Equity Investment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]			(7)		0
Pension and non-pension postretirement benefit plans:
Other Comprehensive Income (Loss), Net of Tax	[1]			(7)		0
Accumulated Equity Investment [Member] | PEPCO Holdings Inc [Member] | Predecessor [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax				0		0
Pension and non-pension postretirement benefit plans:
Other Comprehensive Income (Loss), Net of Tax				0		0
Accumulated Equity Investment [Member] | Exelon Generation Co L L C [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]			(4)		0
Pension and non-pension postretirement benefit plans:
Other Comprehensive Income (Loss), Net of Tax	[1]			$ (4)		0
Accumulated Equity Investment [Member] | PECO Energy Co [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]					$ 0
[1]	All amounts are net of tax. Amounts in parenthesis represent a decrease in AOCI.

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		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 267	$ 638	$ 440	$ 1,331
Weighted average common shares outstanding — basic	924	863	923	862
Assumed exercise and/or distributions of stock-based awards	2	3	3	4
Weighted average common shares outstanding — diluted	926	866	926	866

Earnings Per Share and Equit106

Earnings Per Share and Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Statement Of Equity Line Item [Line Items]
Stock options not included in the calculation of diluted common shares outstanding		13,000,000
Treasury Stock, Shares held	35,000,000		35,000,000
Treasury Stock, Value	$ (2,327)		$ (2,327)		$ (2,327)
Preferred Stock, Value, Issued	$ 193		$ 193		193
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	1,000,000	2,000,000	1,000,000
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		12,000,000	15,000,000
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	$ 190		$ 190		$ 190
Stock Redeemed or Called During Period, Value	100
Preferred Stock, Value, Outstanding	$ 90		$ 90

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Equity Investment Commitments (Details) - Exelon Generation Co L L C [Member] $ in Millions	Jun. 30, 2016USD ($)
Equity Unit Purchase Agreements [Member]
Guarantor Obligations [Line Items]
Other Unrecorded Amounts	$ 20
Unrecorded Unconditional Purchase Obligation, Due in Next Twelve Months	203
2,015	22
2,016	10
Total	235
Noncontrolling Interest [Member]
Guarantor Obligations [Line Items]
Other Unrecorded Amounts	$ 90

Commitments and Contingencie108

Commitments and Contingencies - Commitments Narrative (Details) $ in Millions		3 Months Ended	6 Months Ended
		Jun. 30, 2016USD ($)	Jun. 30, 2016USD ($)MW	Jun. 30, 2015USD ($)	Jun. 30, 2013USD ($)
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted		$ 50	$ 50
Noncash Merger Related Costs	[1],[2]		503
Exelon Generation Co L L C [Member]
Guarantor Obligations [Line Items]
Noncash Merger Related Costs	[2]		3
Costs Incurred, Development Costs		402
Baltimore Gas and Electric Company [Member]
Guarantor Obligations [Line Items]
Business Acquisition, Direct Investment With State And Local Governments Due To Settlement					$ 1,000
Minimum [Member] | Exelon Generation Co L L C [Member]
Guarantor Obligations [Line Items]
Business Acquisition, Construction Cost				$ 95
Business Acquisition, Development Of New Generation Cost		500	$ 500
Business Acquisition, Expected New Generation Mwh | MW			275
Maximum [Member] | Exelon Generation Co L L C [Member]
Guarantor Obligations [Line Items]
Business Acquisition, Construction Cost				$ 120
Business Acquisition, Development Of New Generation Cost		600	$ 600
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		$ 22	$ 22
[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	Jun. 30, 2016	Jul. 31, 2014
Guarantor Obligations [Line Items]
Other Commitment	$ 6,399
Guarantor Obligations, Maximum Exposure, Undiscounted	50
Financial Standby Letter of Credit [Member]
Guarantor Obligations [Line Items]
Other Commitment	1,651
Guarantee of Indebtedness of Others [Member]
Guarantor Obligations [Line Items]
Other Commitment	628
Surety Bond [Member]
Guarantor Obligations [Line Items]
Other Commitment	1,055
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	5,589	$ 91
Exelon Generation Co L L C [Member] | Financial Standby Letter of Credit [Member]
Guarantor Obligations [Line Items]
Other Commitment	1,580
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	964
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	262
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	10
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	14
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	5
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	16
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	6 Months Ended
	Jun. 30, 2016	Jun. 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
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		6 Months Ended
	Aug. 31, 2015gal	Oct. 31, 2007USD ($)	Jun. 30, 2016USD ($)MGPSitegal
Exelon Generation Co L L C [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Consent decree penalty		$ 1
Environmental loss contingencies			$ 11
PEPCO Holdings Inc [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Sites under study/remediation | MGPSite			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
PEPCO Holdings Inc [Member] | Maximum [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss			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
Calpine Corporation [Member] | Maximum [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss			$ 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
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

Commitments and Contingencie112

Commitments and Contingencies - Litigation and Regulatory Matters (Details) $ in Millions	3 Months Ended
	Jun. 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	63,000,000
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	85,000,000

Commitments and Contingencie113

Commitments and Contingencies - Schedule of Accruals for Environmental Matters (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Total Accrual For Environmental Loss Contingencies [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	$ 410	$ 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	66	63
Total Accrual For Environmental Loss Contingencies [Member] | Commonwealth Edison Co [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	277	266
Total Accrual For Environmental Loss Contingencies [Member] | PECO Energy Co [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	35	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	311	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	275	264
Accrual For MGP Investigation And Remediation [Member] | PECO Energy Co [Member]
Accrual For Environmental Loss Contingencies [Line Items]
Accrued environmental liabilities	33	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	6 Months Ended
	Jun. 30, 2015	Jun. 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		16	$ 15
Low To Medium Risk [Member] | PECO Energy Co [Member]
Supplemental Financial Information Tables [Line Items]
Financing Receivable, Net	1	1
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	$ 12

Supplemental Financial Infor115

Supplemental Financial Information - Operations (Detail) - USD ($) $ in Millions		Mar. 31, 2016	Jun. 30, 2016	Jun. 30, 2016	Mar. 23, 2016	Jun. 30, 2015		Jun. 30, 2016	Jun. 30, 2015
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes			$ 217			$ 132		$ 369	$ 279
Decommissioning-Related Activities [Abstract]
Net realized income on decommissioning trust funds - Regulatory Agreement Units			90			93	[1]	122	164	[1]
Net realized income on decommissioning trust funds - Non-Regulatory Agreement Units			39			74	[1]	61	104	[1]
Net unrealized income (losses) on decommissioning trust funds - Regulatory Agreement Units			52			(133)		131	(85)
Net unrealized income (losses) on decommissioning trust funds - Non-Regulatory Agreement			48			(96)		100	(56)
Net unrealized income (losses) on pledged assets			1					3	9
Regulatory offset to decommissioning trust fund-related activities			(117)			28	[2]	(211)	(78)	[2]
Total decommissioning-related activities			113			(34)		206	58
Investment income			(6)			(1)		(12)	(4)
Long-term lease income						(4)		(4)	(8)
Unrecognized Tax Benefits Interest Income			4					5	0
AFUDC - equity			(15)			(5)		(24)	(11)
Gain (Loss) on Disposition of Assets	[3]								(26)
Gains (Losses) on Extinguishment of Debt								(3)
Other Income			6			7		10	9
Other, net			144			(17)		258	64
Exelon Generation Co L L C [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes			27			24		55	51
Decommissioning-Related Activities [Abstract]
Net realized income on decommissioning trust funds - Regulatory Agreement Units			90			93	[1]	122	164	[1]
Net realized income on decommissioning trust funds - Non-Regulatory Agreement Units			39			74	[1]	61	104	[1]
Net unrealized income (losses) on decommissioning trust funds - Regulatory Agreement Units			52			(133)		131	(85)
Net unrealized income (losses) on decommissioning trust funds - Non-Regulatory Agreement			48			(96)		100	(56)
Net unrealized income (losses) on pledged assets			1					3	9
Regulatory offset to decommissioning trust fund-related activities			(117)			28	[2]	(211)	(78)	[2]
Total decommissioning-related activities			113			(34)		206	58
Investment income			(5)			0		(5)	(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			(1)			3		1	2
Other, net			117			(31)		210	62
Commonwealth Edison Co [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes			60			55		119	117
Decommissioning-Related Activities [Abstract]
Investment income			0
Unrecognized Tax Benefits Interest Income								0	0
AFUDC - equity			(1)			(1)		(3)	(1)
Other Income			2			4		4	8
Other, net			3			5		7	9
PECO Energy Co [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes			32			32		66	67
Decommissioning-Related Activities [Abstract]
Investment income			0			1		1	1
Unrecognized Tax Benefits Interest Income			0					0	0
AFUDC - equity			(2)			(1)		(4)	(3)
Other Income			0			1		1	1
Other, net			2			1		4	3
Baltimore Gas and Electric Company [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes			21			21		45	44
Decommissioning-Related Activities [Abstract]
Investment income			0			(1)	[4]	(2)	(2)	[4]
Unrecognized Tax Benefits Interest Income			0					0
AFUDC - equity			(5)			(3)		(9)	(7)
Other Income			0			0		0	(1)
Other, net			5			4		11	8
Potomac Electric Power Company [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes			73			77		152	157
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)		(9)	(6)
Gain (Loss) on Disposition of Assets			8					8
Other Income			1			5		4	7
Other, net			6			8		14	13
Pepco Holdings LLC [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes		$ 84	77		$ 77	81			166
Pepco Holdings LLC [Member] | Successor [Member]
Decommissioning-Related Activities [Abstract]
Investment income		0
Long-term lease income		0
Unrecognized Tax Benefits Interest Income		0
AFUDC - equity		(8)	(7)
Other Income		4	4
Other, net		$ 12	11	$ 12
Pepco Holdings LLC [Member] | Predecessor [Member]
Decommissioning-Related Activities [Abstract]
Investment income					0				0
Long-term lease income					0				0
Unrecognized Tax Benefits Interest Income					0				0
AFUDC - equity					(7)	(3)			(7)
Other Income					(11)	9			14
Other, net					$ (4)	12			21
Delmarva Power and Light Company [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes			4			4		9	9
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		(2)	0
Other Income			2			2		4	5
Other, net			3			2		6	5
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	0
AFUDC - equity			(1)			0		(3)	(1)
Gain (Loss) on Disposition of Assets			1					1
Other Income			1			1		1	2
Other, net			$ 2			$ 1		$ 5	$ 3
[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		Mar. 31, 2016	Jun. 30, 2016	Jun. 30, 2016	Mar. 23, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Mar. 24, 2016
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]						$ 1,432	$ 1,087
Regulatory assets	[1]						166	101
Amortization of intangible assets, net	[1]						28	24
Amortization of energy contract assets and liabilities	[2]						(7)	0
Nuclear fuel	[3]						557	552
Total depreciation, amortization and accretion							2,396	1,957
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense			$ 160			$ 160	297	317
Gain (loss) on equity method investments							10	2
Provision for uncollectible accounts							51	80
Stock-based compensation costs							67	79
Other Decommissioning Related Activity	[4]						(123)	(50)
Energy-related options	[5]						(17)	27
Amortization of regulatory asset related to debt costs							4	0
Amortization of rate stabilization deferral							(34)	(40)
Amortization of debt fair value adjustment							(6)	(37)
Discrete impacts from EIMA	[6]						(21)	77
Amortization of debt costs							(14)	(35)
Merger related commitments	[7],[8]						503
Severance Obligation Severance Charges							122
Inventory Write-down							68
InventoryLCMReservePeriodCharge							36	13
Other							17	(4)
Total other noncash operating activities							1,056	579
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities							(593)	(156)
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Non cash Fair Value Adjustment for CENG							0	95
Payments to Acquire Businesses, Gross							6,642	28
Capital Expenditures Incurred but Not yet Paid							(364)
Capitalized Costs, Asset Retirement Costs			471	$ 471			471
Asset Retirement Obligation, Accretion Expense	[9]						220	193
Capital Project [Member]
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Noncash or Part Noncash Acquisition, Fixed Assets Acquired							60
Exelon Generation Co L L C [Member]
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]						674	485
Amortization of intangible assets, net	[1]						23	24
Amortization of energy contract assets and liabilities	[2]						(7)	1
Nuclear fuel	[3]						557	552
Total depreciation, amortization and accretion							1,467	1,255
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense			55			68	109	133
Gain (loss) on equity method investments							11	3
Provision for uncollectible accounts							13	11
Stock-based compensation costs							0	0
Other Decommissioning Related Activity	[4]						(123)	(50)
Energy-related options	[5]						(17)	27
Amortization of regulatory asset related to debt costs							0	0
Amortization of rate stabilization deferral							0	0
Amortization of debt fair value adjustment							(6)	(6)
Discrete impacts from EIMA							0	0
Amortization of debt costs							(10)	(8)
Merger related commitments	[8]						3
Severance Obligation Severance Charges							50
Inventory Write-down							66
InventoryLCMReservePeriodCharge							36	13
Other							17	(5)
Total other noncash operating activities							169	134
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities							(217)	(155)
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Non cash Fair Value Adjustment for CENG	[8]						119
Payments to Acquire Businesses, Gross							1	28
Capital Expenditures Incurred but Not yet Paid							(317)
Capitalized Costs, Asset Retirement Costs			471	471			471
Asset Retirement Obligation, Accretion Expense	[9]						220	193
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							60
Commonwealth Edison Co [Member]
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]						345	312
Regulatory assets	[1]						34	40
Total depreciation, amortization and accretion							379	352
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense			42			51	83	103
Gain (loss) on equity method investments							0	0
Provision for uncollectible accounts							18	35
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	0
Amortization of rate stabilization deferral							0	0
Amortization of debt fair value adjustment							0	0
Discrete impacts from EIMA	[6]						(21)	77
Amortization of debt costs							(2)	(2)
Inventory Write-down							2
InventoryLCMReservePeriodCharge								0
Other							(3)	5
Total other noncash operating activities							83	222
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities							38	26
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							(21)
Capitalized Costs, Asset Retirement Costs			0	0			0
Commonwealth Edison Co [Member] | Indemnification Agreement [Member]
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Contribution of Property	[10]						5	3
PECO Energy Co [Member]
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]						121	119
Regulatory assets	[1]						13	12
Total depreciation, amortization and accretion							134	131
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense			8			10	17	19
Gain (loss) on equity method investments							0	0
Provision for uncollectible accounts							10	24
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							(1)	(1)
Inventory Write-down							0
InventoryLCMReservePeriodCharge								0
Other							(2)	1
Total other noncash operating activities							27	45
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities							(96)	(60)
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Non cash Fair Value Adjustment for CENG							0
Capital Expenditures Incurred but Not yet Paid							(12)
Capitalized Costs, Asset Retirement Costs			0	0			0
Baltimore Gas and Electric Company [Member]
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]						150	143
Regulatory assets	[1]						56	49
Total depreciation, amortization and accretion							206	192
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense			18			17	33	33
Gain (loss) on equity method investments							0	0
Provision for uncollectible accounts							3	11
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							(34)	(40)
Amortization of debt fair value adjustment							0	0
Discrete impacts from EIMA							0	0
Amortization of debt costs							(2)	(1)
Inventory Write-down							0
InventoryLCMReservePeriodCharge								0
Other							(12)	(9)
Total other noncash operating activities							60	76
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities							(3)	61
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Non cash Fair Value Adjustment for CENG							0
Capital Expenditures Incurred but Not yet Paid							2
Capitalized Costs, Asset Retirement Costs			0	0			0
Asset Retirement Obligation, Accretion Expense							0
Potomac Electric Power Company [Member]
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]						85	81
Regulatory assets	[1]						59	44
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							144	125
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense	[11]		7			7	16	15
Gain (loss) on equity method investments							0	0
Provision for uncollectible accounts							8	9
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	1
Amortization of rate stabilization deferral							2	(8)
Amortization of debt fair value adjustment							0	0
Discrete impacts from EIMA							0	0
Amortization of debt costs							0	0
Merger related commitments	[8]						138
Inventory Write-down							1
Other							(4)	0
Total other noncash operating activities							158	33
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities							(47)	(36)
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
Asset Retirement Obligation, Accretion Expense	[9]						0	0
Delmarva Power and Light Company [Member]
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]						55	50
Regulatory assets	[1]						21	24
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							4
Total depreciation, amortization and accretion							76	74
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense	[11]		4			4	9	8
Gain (loss) on equity method investments							0	0
Provision for uncollectible accounts							8	12
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							(2)	(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]						100
Inventory Write-down							1
Other							(3)	1
Total other noncash operating activities							121	22
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities							(51)	(4)
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Non cash Fair Value Adjustment for CENG							0
Capital Expenditures Incurred but Not yet Paid							(9)
Asset Retirement Obligation, Accretion Expense	[9]						0	0
Asset Retirement Obligation, Revision of Estimate							(4)
Atlantic City Electric Company [Member]
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]						40	38
Regulatory assets	[1]						41	48
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							81	86
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense	[11]		4			4	8	8
Gain (loss) on equity method investments							0	0
Provision for uncollectible accounts							10	9
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							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]						120
Inventory Write-down							1
Other							(3)	0
Total other noncash operating activities							138	17
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities							(110)	(24)
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Non cash Fair Value Adjustment for CENG							0
Capital Expenditures Incurred but Not yet Paid							6
Asset Retirement Obligation, Accretion Expense	[9]						0	0
Asset Retirement Obligation, Revision of Estimate							$ (2)
Pepco Holdings LLC [Member]
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense			$ 27	31
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			193
Regulatory assets	[1]				58			114
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			307
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense					23	$ 24		48
Gain (loss) on equity method investments					0
Provision for uncollectible accounts					16			30
Stock-based compensation costs					3			6
Other Decommissioning Related Activity					0			0
Energy-related options					0			0
Amortization of regulatory asset related to debt costs					1			2
Amortization of rate stabilization deferral					(5)			(9)
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)			4
Total other noncash operating activities					46			101
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities					(9)			(63)
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Asset Retirement Obligation, Accretion Expense	[9]				$ 0			$ 0
Pepco Holdings LLC [Member] | Successor [Member]
Depreciation, Amortization and Accretion [Abstract]
Depreciation	[1]	$ 111
Regulatory assets	[1]	63
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		174		174
Other Non-Cash Operating Activities [Abstract]
Pension and Other Postretirement Benefit Expense				31
Gain (loss) on equity method investments				0
Provision for uncollectible accounts				7
Stock-based compensation costs				0
Other Decommissioning Related Activity				0
Energy-related options				0
Amortization of regulatory asset related to debt costs				1
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]			358
Severance Obligation Severance Charges				54
Inventory Write-down				0
Other				(7)
Total other noncash operating activities				444
Changes In Other Assets and Liabilities [Abstract]
Total changes in other assets and liabilities				(237)
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Non cash Fair Value Adjustment for CENG				127
Business Combination, Contingent Consideration, Liability, Noncurrent									$ 53
Capital Expenditures Incurred but Not yet Paid				(4)
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				62
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		$ 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
[11]	Pepco's, DPL's, ACE's and PHISCO's pension and postretirement benefit costs for the six months ended June 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.

Supplemental Financial Infor117

Supplemental Financial Information - Balance Sheet (Details) - USD ($) $ in Millions	Jun. 30, 2016		Dec. 31, 2015
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	$ 17,340	[1]	$ 16,375	[2]
Accounts receivable, net
Allowance for uncollectible accounts	314		284
Exelon Generation Co L L C [Member]
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	9,179	[1]	8,639	[2]
Accounts receivable, net
Allowance for uncollectible accounts	82		77
Exelon Generation Co L L C [Member] | Nuclear Fuel [Member]
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	2,936		2,861
Commonwealth Edison Co [Member]
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	3,785		3,710
Accounts receivable, net
Allowance for uncollectible accounts	74		75
PECO Energy Co [Member]
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	3,185		3,101
Accounts receivable, net
Allowance for uncollectible accounts	75		83
Baltimore Gas and Electric Company [Member]
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	3,161		3,016
Accounts receivable, net
Allowance for uncollectible accounts	33		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	83
Accounts receivable, net
Allowance for uncollectible accounts	50
Potomac Electric Power Company [Member]
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	2,995		2,929
Accounts receivable, net
Allowance for uncollectible accounts	16		17
Delmarva Power and Light Company [Member]
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	1,157		1,139
Accounts receivable, net
Allowance for uncollectible accounts	17		17
Atlantic City Electric Company [Member]
Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation	998		968
Accounts receivable, net
Allowance for uncollectible accounts	$ 17		$ 17
[1]	Includes accumulated amortization of nuclear fuel in the reactor core of $2,936 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	Mar. 31, 2016	Jun. 30, 2016	Mar. 23, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes		$ 217		$ 132	$ 369	$ 279
Exelon Generation Co L L C [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes		27		24	55	51
Commonwealth Edison Co [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes		60		55	119	117
PECO Energy Co [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes		32		32	66	67
Baltimore Gas and Electric Company [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes		21		21	45	44
Pepco Holdings LLC [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes	$ 84	77	$ 77	81		166
Potomac Electric Power Company [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes		73		77	152	157
Delmarva Power and Light Company [Member]
Supplemental Income Statement Information [Line Items]
Utilities Operating Expense, Taxes		4		4	9	9
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)	6 Months Ended
	Jun. 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
	Jun. 30, 2016		Jun. 30, 2016	Mar. 23, 2016	Jun. 30, 2015		Jun. 30, 2016		Jun. 30, 2015		Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues	$ 6,910				$ 6,514		$ 14,485		$ 15,345
Competitive Energy Revenue	3,301				3,512		6,732		7,699
Electric Revenue	3,480				2,270		6,136		4,844
Other Operating Income	(434)				137		(213)		460
Revenue from Purchased Oil and Gas	367				431		1,189		1,555
Operating revenues from affiliates	1				1
Net income (loss)	306				633		430		1,372
Assets	112,778		$ 112,778				112,778				$ 95,384
Gas Domestic Regulated Revenue	197				165		641		788
Sales Revenue, Services, Other	(1)				(1)		0		(1)
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)	(52)				28		(215)		(55)
Assets	10,069		10,069				10,069				15,389
Gas Domestic Regulated Revenue	0				0		0		0
Sales Revenue, Services, Other	398				340		803		657
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Competitive Energy Revenue	(354)				(151)		(620)		(360)
Electric Revenue	(7)				(1)		(15)		(2)
Other Operating Income	(1)				(1)		(1)		0
Revenue from Purchased Oil and Gas	0				0		0		0
Operating revenues from affiliates	(771)				(493)		2		1
Net income (loss)	(1)				(1)		(2)		(3)
Assets	(12,125)		(12,125)				(12,125)				(11,728)
Gas Domestic Regulated Revenue	(2)				(1)		(5)		(9)
Sales Revenue, Services, Other	(409)				(341)		(826)		(658)
Intersegment Eliminations [Member] | Successor [Member]
Segment Reporting Information [Line Items]
Electric Revenue	(4)		(5)
Operating revenues from affiliates	(4)		(5)
Net income (loss)	10		23
Assets	(4,652)		(4,652)				(4,652)
Gas Domestic Regulated Revenue	0		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)	(4)				(7)
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	3,655				3,663		7,352		8,059
Electric Revenue	0				0		0		0
Other Operating Income	(433)				138		(212)		460
Revenue from Purchased Oil and Gas	367				431		1,189		1,555
Net income (loss)	28				390		285		875
Assets	46,897		46,897				46,897				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	355				152		621		360
Generation Midwest [Member]
Segment Reporting Information [Line Items]
Revenues	1,083				1,206		2,179		2,482
Generation Midwest [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	1,076	[1]			1,206	[1]	2,166	[2]	2,482	[2]
Generation Midwest [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	7				0		13		0
Commonwealth Edison Co [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Competitive Energy Revenue	0				0		0		0
Electric Revenue	1,286				1,148		2,535		2,333
Other Operating Income	0				0		0		0
Revenue from Purchased Oil and Gas	0				0		0		0
Net income (loss)	145				99		260		189
Assets	28,105		28,105				28,105				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	3				1		8		2
PECO Energy Co [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Competitive Energy Revenue	0				0		0		0
Electric Revenue	587				582		1,232		1,259
Other Operating Income	0				0		0		0
Revenue from Purchased Oil and Gas	0				0		0		0
Net income (loss)	100				70		224		209
Assets	10,586		10,586				10,586				10,367
Gas Domestic Regulated Revenue	77				79		273		387
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				0		4		1
Baltimore Gas and Electric Company [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Competitive Energy Revenue	0				0		0		0
Electric Revenue	584				541		1,264		1,254
Other Operating Income	0				0		0		0
Revenue from Purchased Oil and Gas	0				0		0		0
Net income (loss)	34				47		135		157
Assets	8,325		8,325				8,325				8,295
Gas Domestic Regulated Revenue	96				87		345		410
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	4				1		9		8
Corporate and Other [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates							803		656
Pepco Holdings LLC [Member] | Successor [Member]
Segment Reporting Information [Line Items]
Electric Revenue	1,030		1,120
Net income (loss)	52		(257)
Gas Domestic Regulated Revenue	26		28
Sales Revenue, Services, Other	10		23
Pepco Holdings LLC [Member] | Predecessor [Member]
Segment Reporting Information [Line Items]
Electric Revenue				1,096	1,094				2,362
Net income (loss)				19
Gas Domestic Regulated Revenue				57	25				111
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	10		23
Net income (loss)	(22)		0
Assets	11,042		11,042				11,042
Gas Domestic Regulated Revenue	0		(1)
Sales Revenue, Services, Other	10		23
Pepco Holdings LLC [Member] | Corporate, Non-Segment [Member] | Predecessor [Member]
Segment Reporting Information [Line Items]
Electric Revenue				42	59				115
Operating revenues from affiliates				0	0				0
Net income (loss)				(44)	(3)				(17)
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	1,030				0		1,120		0
Other Operating Income	0						0		0
Revenue from Purchased Oil and Gas	0						0		0
Operating revenues from affiliates	10		23
Net income (loss)	52				0		(257)		0
Assets	20,921		20,921				20,921				0
Gas Domestic Regulated Revenue	26				0		28		0
Sales Revenue, Services, Other	10				0		23		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)					53				106
Assets											16,188
Pepco Holdings LLC [Member] | Intersegment Eliminations [Member] | Successor [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates	10				0		23		0
Corporate, Non-Segment [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates	398				340
Segment Elimination [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates							(1,466)		(1,026)
Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Revenues	3,589				4,232		8,329		10,074
Generation Total Consolidated Group [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	3,589	[1]			4,232	[1]	8,329	[2]	10,074	[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	509		550
Operating revenues from affiliates	1		2
Net income (loss)	49		(92)
Assets	7,099		7,099				7,099
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	504				1,049
Operating revenues from affiliates				1	1				2
Net income (loss)				32	42				68
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	255		279
Operating revenues from affiliates	2		2
Net income (loss)	12		(86)
Assets	3,971		3,971				3,971
Gas Domestic Regulated Revenue	26		29
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	246				580
Operating revenues from affiliates				2	2				3
Net income (loss)				26	8				40
Assets											3,969
Gas Domestic Regulated Revenue				56	25				111
Sales Revenue, Services, Other				0	0				0
Atlantic City Electric Company [Member] | Operating Segments [Member] | Successor [Member]
Segment Reporting Information [Line Items]
Electric Revenue	270		293
Operating revenues from affiliates	1		1
Net income (loss)	3		(102)
Assets	3,461		3,461				3,461
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	285				618
Operating revenues from affiliates				1	1				2
Net income (loss)				5	6				15
Assets											$ 3,387
Gas Domestic Regulated Revenue				0	0				0
Sales Revenue, Services, Other				$ 0	0				0
Operating Segments [Member] | PECO Energy Co Affiliate [Member]
Segment Reporting Information [Line Items]
Revenues					49		143		112
Operating Segments [Member] | PECO Energy Co Affiliate [Member] | Generation Midwest [Member]
Segment Reporting Information [Line Items]
Revenues	64
Operating Segments [Member] | Baltimore Gas And Electric Company Affiliate [Member] | Generation Midwest [Member]
Segment Reporting Information [Line Items]
Revenues	135				97		306		235
Operating Segments [Member] | Commonwealth Edison Co Affiliate [Member] | Generation Midwest [Member]
Segment Reporting Information [Line Items]
Revenues	13				$ 6		$ 18		$ 15
Operating Segments [Member] | PotomacElectricPowerCompanyAffiliate [Member] | Generation Midwest [Member]
Segment Reporting Information [Line Items]
Revenues	88
Operating Segments [Member] | PotomacElectricPowerCompanyAffiliate [Member] | Generation Midwest [Member] | Successor [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates	94
Operating Segments [Member] | DelmarvaPowerandLightCompanyAffiliate [Member] | Generation Midwest [Member]
Segment Reporting Information [Line Items]
Revenues	43
Operating Segments [Member] | DelmarvaPowerandLightCompanyAffiliate [Member] | Generation Midwest [Member] | Successor [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates	47
Operating Segments [Member] | AtlanticCityElectricCompanyAffiliate [Member] | Generation Midwest [Member]
Segment Reporting Information [Line Items]
Revenues	12
Operating Segments [Member] | AtlanticCityElectricCompanyAffiliate [Member] | Generation Midwest [Member] | Successor [Member]
Segment Reporting Information [Line Items]
Operating revenues from affiliates	$ 13
[1]	Three Months Ended June 30, 2016 Three Months Ended June 30, 2015 Revenuesfrom externalcustomers(a)IntersegmentrevenuesTotalRevenuesRevenuesfrom externalcustomers(a)(c)Intersegmentrevenues(c)TotalRevenues(c)Mid-Atlantic$1,432 $(16) $1,416 $1,364 $(18) $1,346Midwest1,076 7 1,083 1,206 — 1,206New England352 (1) 351 367 — 367New York356 (10) 346 222 (4) 218ERCOT207 — 207 194 (2) 192Other Power Regions232 (9) 223 310 (21) 289Total Revenues for Reportable Segments3,655 (29) 3,626 3,663 (45) 3,618Other(b)(66) 29 (37) 569 45 614Total Generation Consolidated Operating Revenues$3,589 $— $3,589 $4,232 $— $4,232
[2]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmYxYjEyZjM4YzVjZDQ2YTM5N2E5NDQ4NWM2Nzk3Yjg1fFRleHRTZWxlY3Rpb246N0MwQjhEMjI5NzREODVBMzQxQjhDNTVBNUYzRTA3MDcM}

Segment Information - Generatio

Segment Information - Generation Total Revenues (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2016		Jun. 30, 2015		Jun. 30, 2016		Jun. 30, 2015
Segment Reporting Information [Line Items]
Revenues	$ (6,910)		$ (6,514)		$ (14,485)		$ (15,345)
Revenue from Related Parties	(1)		(1)
Net income (loss)	306		633		430		1,372
Derivative, Loss on Derivative	(3)
Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Revenues	(1,416)		(1,346)		(2,936)		(2,859)
Generation New England [Member]
Segment Reporting Information [Line Items]
Revenues	(351)		(367)		(821)		(1,226)
Generation New York [Member]
Segment Reporting Information [Line Items]
Revenues	(346)		(218)		(549)		(528)
Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Revenues	(207)		(192)		(370)		(372)
Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Revenues	(223)		(289)		(447)		(503)
Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Revenues	(3,626)		(3,618)		(7,302)		(7,970)
Generation Reportable Segments Total [Member] | Scenario, Adjustment [Member]
Segment Reporting Information [Line Items]
Revenues			(46)				(89)
Revenue from Related Parties			(46)				(89)
Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues	37		(614)		(1,027)		(2,104)
Amortization of intangible assets related to commodity contracts	(9)		(17)		11		22
Derivative, Gain on Derivative			25				179
Derivative, Loss on Derivative	(615)				(553)
Generation All Other Segments [Member] | Scenario, Adjustment [Member]
Segment Reporting Information [Line Items]
Revenues			(46)				89
Revenue from Related Parties			(46)				(89)
Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Revenues	(3,589)		(4,232)		(8,329)		(10,074)
Operating Segments [Member] | Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Revenues	(1,432)	[1]	(1,364)	[1]	(2,964)	[2],[3]	(2,920)	[2],[3]
Operating Segments [Member] | Generation New England [Member]
Segment Reporting Information [Line Items]
Revenues	(352)	[1]	(367)	[1]	(823)	[3]	(1,232)	[3]
Operating Segments [Member] | Generation New York [Member]
Segment Reporting Information [Line Items]
Revenues	(356)	[1]	(222)	[1]	(573)	[2],[3]	(529)	[2],[3]
Operating Segments [Member] | Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Revenues	(207)	[1]	(194)	[1]	(370)	[3]	(375)	[3]
Operating Segments [Member] | Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Revenues	(232)	[1],[4]	(310)	[1],[4]	(456)	[3],[5]	(522)	[3],[5]
Operating Segments [Member] | Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Revenues	(3,655)	[1]	(3,663)	[1]	(7,352)	[3]	(8,060)	[3]
Operating Segments [Member] | Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Revenues	(3,589)	[1]	(4,232)	[1]	(8,329)	[3]	(10,074)	[3]
Operating Segments [Member] | Exelon Generation Co L L C [Member]
Segment Reporting Information [Line Items]
Net income (loss)	28		390		285		875
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Net income (loss)	(52)		28		(215)		(55)
Corporate, Non-Segment [Member] | Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues	66	[1],[6]	(569)	[1],[6]	(977)	[3],[7]	(2,014)	[3],[7]
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties	771		493		(2)		(1)
Net income (loss)	(1)		(1)		(2)		(3)
Intersegment Eliminations [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties					(803)		(656)
Intersegment Eliminations [Member] | Segment Elimination [Member]
Segment Reporting Information [Line Items]
Revenue from Related Parties					1,466		1,026
Intersegment Eliminations [Member] | Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Revenues	16		18		28	[2]	61	[2]
Intersegment Eliminations [Member] | Generation New England [Member]
Segment Reporting Information [Line Items]
Revenues	1		0		2		6
Intersegment Eliminations [Member] | Generation New York [Member]
Segment Reporting Information [Line Items]
Revenues	10		4		24	[2]	1	[2]
Intersegment Eliminations [Member] | Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Revenues	0		2		0		3
Intersegment Eliminations [Member] | Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Revenues	9	[4]	21	[4]	9	[5]	19	[5]
Intersegment Eliminations [Member] | Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Revenues	29		45		50		90
Intersegment Eliminations [Member] | Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues	(29)	[6]	(45)	[6]	(50)	[7]	(90)	[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	$ (355)		$ (152)		$ (621)		$ (360)
[1]	Three Months Ended June 30, 2016 Three Months Ended June 30, 2015 Revenuesfrom externalcustomers(a)IntersegmentrevenuesTotalRevenuesRevenuesfrom externalcustomers(a)(c)Intersegmentrevenues(c)TotalRevenues(c)Mid-Atlantic$1,432 $(16) $1,416 $1,364 $(18) $1,346Midwest1,076 7 1,083 1,206 — 1,206New England352 (1) 351 367 — 367New York356 (10) 346 222 (4) 218ERCOT207 — 207 194 (2) 192Other Power Regions232 (9) 223 310 (21) 289Total Revenues for Reportable Segments3,655 (29) 3,626 3,663 (45) 3,618Other(b)(66) 29 (37) 569 45 614Total Generation Consolidated Operating Revenues$3,589 $— $3,589 $4,232 $— $4,232
[2]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmYxYjEyZjM4YzVjZDQ2YTM5N2E5NDQ4NWM2Nzk3Yjg1fFRleHRTZWxlY3Rpb246MjczNzA5QThFQTg3QjUwRUNENjZDNTVBNUYzRTFGRTQM}
[3]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmYxYjEyZjM4YzVjZDQ2YTM5N2E5NDQ4NWM2Nzk3Yjg1fFRleHRTZWxlY3Rpb246N0MwQjhEMjI5NzREODVBMzQxQjhDNTVBNUYzRTA3MDcM}
[4]	Three Months Ended June 30, 2016 Three Months Ended June 30, 2015 Revenuesfrom externalcustomers(a)IntersegmentrevenuesTotalRevenuesRevenuesfrom externalcustomers(a)(c)Intersegmentrevenues(c)TotalRevenues(c)Mid-Atlantic$1,432 $(16) $1,416 $1,364 $(18) $1,346Midwest1,076 7 1,083 1,206 — 1,206New England352 (1) 351 367 — 367New York356 (10) 346 222 (4) 218ERCOT207 — 207 194 (2) 192Other Power Regions232 (9) 223 310 (21) 289Total Revenues for Reportable Segments3,655 (29) 3,626 3,663 (45) 3,618Other(b)(66) 29 (37) 569 45 614Total Generation Consolidated Operating Revenues$3,589 $— $3,589 $4,232 $— $4,232
[5]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmYxYjEyZjM4YzVjZDQ2YTM5N2E5NDQ4NWM2Nzk3Yjg1fFRleHRTZWxlY3Rpb246QzdEMzkzREYyOEI0NjREREJDNzVDNTVBNUYzRTI3QjIM}
[6]	Three Months Ended June 30, 2016 Three Months Ended June 30, 2015 Revenuesfrom externalcustomers(a)IntersegmentrevenuesTotalRevenuesRevenuesfrom externalcustomers(a)(c)Intersegmentrevenues(c)TotalRevenues(c)Mid-Atlantic$1,432 $(16) $1,416 $1,364 $(18) $1,346Midwest1,076 7 1,083 1,206 — 1,206New England352 (1) 351 367 — 367New York356 (10) 346 222 (4) 218ERCOT207 — 207 194 (2) 192Other Power Regions232 (9) 223 310 (21) 289Total Revenues for Reportable Segments3,655 (29) 3,626 3,663 (45) 3,618Other(b)(66) 29 (37) 569 45 614Total Generation Consolidated Operating Revenues$3,589 $— $3,589 $4,232 $— $4,232
[7]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmYxYjEyZjM4YzVjZDQ2YTM5N2E5NDQ4NWM2Nzk3Yjg1fFRleHRTZWxlY3Rpb246RTI5RThGNUMzRjQyMjZCRTY4ODlDNTVBNUYzRUU2MEQM}

Segment Information - Genera122

Segment Information - Generation Total Revenues Net of Purchased Power and Fuel Expense (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2016		Jun. 30, 2015		Jun. 30, 2016		Jun. 30, 2015
Segment Reporting Information [Line Items]
Revenues		$ 6,910		$ 6,514		$ 14,485		$ 15,345
Unrealized Gain (Loss) on Derivatives						(194)		507
Nuclear Fuel Amortization	[1]					557		552
Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel		2,012		2,383		4,309		4,792
Revenues		3,589		4,232		8,329		10,074
Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel		828		892		1,669		1,679
Revenues		1,416		1,346		2,936		2,859
Generation Midwest [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel		728		745		1,449		1,448
Revenues		1,083		1,206		2,179		2,482
Generation New England [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel		110		88		191		246
Revenues		351		367		821		1,226
Generation New York [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel		267		145		395		334
Revenues		346		218		549		528
Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel		77		70		138		125
Revenues		207		192		370		372
Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel		96		62		174		108
Revenues		223		289		447		503
Other Segments [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel				381
Other Segments [Member] | Scenario, Adjustment [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel				6				10
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		(12)		(14)		7		24
Segment Reporting Information Revenue Net of Purchase Power And Fuel		(94)				293		852
Revenues		(37)		614		1,027		2,104
Derivative, Gain on Derivative				25				179
Unrealized Gain (Loss) on Derivatives		(304)		235		(201)		397
Nuclear Fuel Amortization		(9)				(9)
Generation All Other Segments [Member] | Scenario, Adjustment [Member]
Segment Reporting Information [Line Items]
Intersegment RNF				(6)				(25)
Segment Reporting Information Revenue Net of Purchase Power And Fuel								15
Revenues				46				(89)
Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Revenue Net of Purchase Power And Fuel		2,106		2,002		4,016		3,940
Revenues		3,626		3,618		7,302		7,970
Generation Reportable Segments Total [Member] | Scenario, Adjustment [Member]
Segment Reporting Information [Line Items]
Intersegment RNF				6				25
Segment Reporting Information Revenue Net of Purchase Power And Fuel								(10)
Revenues				46				89
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		(2)		1		8		(11)
Revenues		(16)		(18)		(28)	[2]	(61)	[2]
Intersegment Eliminations [Member] | Generation Midwest [Member]
Segment Reporting Information [Line Items]
Intersegment RNF		4		(5)		6		(6)
Revenues		7		0		13		0
Intersegment Eliminations [Member] | Generation New England [Member]
Segment Reporting Information [Line Items]
Intersegment RNF		(8)		(7)		(13)		(31)
Revenues		(1)		0		(2)		(6)
Intersegment Eliminations [Member] | Generation New York [Member]
Segment Reporting Information [Line Items]
Intersegment RNF		(3)		7		(13)		28
Revenues		(10)		(4)		(24)	[2]	(1)	[2]
Intersegment Eliminations [Member] | Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Intersegment RNF		(34)		(21)		(54)		(54)
Revenues		0		(2)		0		(3)
Intersegment Eliminations [Member] | Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Intersegment RNF		(27)		(51)		(37)		(77)
Revenues		(9)	[3]	(21)	[3]	(9)	[4]	(19)	[4]
Intersegment Eliminations [Member] | Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Intersegment RNF		70		76		103		151
Revenues		29	[5]	45	[5]	50	[6]	90	[6]
Intersegment Eliminations [Member] | Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Intersegment RNF		(70)		(76)		(103)		(151)
Revenues		(29)		(45)		(50)		(90)
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		2,012		2,383		4,309		4,792
Revenues		3,589	[7]	4,232	[7]	8,329	[8]	10,074	[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		830		891		1,661		1,690
Revenues		1,432	[7]	1,364	[7]	2,964	[2],[8]	2,920	[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		724		750		1,443		1,454
Revenues		1,076	[7]	1,206	[7]	2,166	[8]	2,482	[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		118		95		204		277
Revenues		352	[7]	367	[7]	823	[8]	1,232	[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		270		138		408		306
Revenues		356	[7]	222	[7]	573	[2],[8]	529	[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		111		91		192		179
Revenues		207	[7]	194	[7]	370	[8]	375	[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		123		113		211		185
Revenues		232	[3],[7]	310	[3],[7]	456	[4],[8]	522	[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		(164)		305		190		701
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		2,176		2,078		4,119		4,091
Revenues		$ 3,655	[7]	$ 3,663	[7]	$ 7,352	[8]	$ 8,060	[8]
[1]	Included in Purchased power and fuel expense on the Registrants’ Consolidated Statements of Operations and Comprehensive Income
[2]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmYxYjEyZjM4YzVjZDQ2YTM5N2E5NDQ4NWM2Nzk3Yjg1fFRleHRTZWxlY3Rpb246MjczNzA5QThFQTg3QjUwRUNENjZDNTVBNUYzRTFGRTQM}
[3]	Three Months Ended June 30, 2016 Three Months Ended June 30, 2015 Revenuesfrom externalcustomers(a)IntersegmentrevenuesTotalRevenuesRevenuesfrom externalcustomers(a)(c)Intersegmentrevenues(c)TotalRevenues(c)Mid-Atlantic$1,432 $(16) $1,416 $1,364 $(18) $1,346Midwest1,076 7 1,083 1,206 — 1,206New England352 (1) 351 367 — 367New York356 (10) 346 222 (4) 218ERCOT207 — 207 194 (2) 192Other Power Regions232 (9) 223 310 (21) 289Total Revenues for Reportable Segments3,655 (29) 3,626 3,663 (45) 3,618Other(b)(66) 29 (37) 569 45 614Total Generation Consolidated Operating Revenues$3,589 $— $3,589 $4,232 $— $4,232
[4]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmYxYjEyZjM4YzVjZDQ2YTM5N2E5NDQ4NWM2Nzk3Yjg1fFRleHRTZWxlY3Rpb246QzdEMzkzREYyOEI0NjREREJDNzVDNTVBNUYzRTI3QjIM}
[5]	Three Months Ended June 30, 2016 Three Months Ended June 30, 2015 Revenuesfrom externalcustomers(a)IntersegmentrevenuesTotalRevenuesRevenuesfrom externalcustomers(a)(c)Intersegmentrevenues(c)TotalRevenues(c)Mid-Atlantic$1,432 $(16) $1,416 $1,364 $(18) $1,346Midwest1,076 7 1,083 1,206 — 1,206New England352 (1) 351 367 — 367New York356 (10) 346 222 (4) 218ERCOT207 — 207 194 (2) 192Other Power Regions232 (9) 223 310 (21) 289Total Revenues for Reportable Segments3,655 (29) 3,626 3,663 (45) 3,618Other(b)(66) 29 (37) 569 45 614Total Generation Consolidated Operating Revenues$3,589 $— $3,589 $4,232 $— $4,232
[6]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmYxYjEyZjM4YzVjZDQ2YTM5N2E5NDQ4NWM2Nzk3Yjg1fFRleHRTZWxlY3Rpb246RTI5RThGNUMzRjQyMjZCRTY4ODlDNTVBNUYzRUU2MEQM}
[7]	Three Months Ended June 30, 2016 Three Months Ended June 30, 2015 Revenuesfrom externalcustomers(a)IntersegmentrevenuesTotalRevenuesRevenuesfrom externalcustomers(a)(c)Intersegmentrevenues(c)TotalRevenues(c)Mid-Atlantic$1,432 $(16) $1,416 $1,364 $(18) $1,346Midwest1,076 7 1,083 1,206 — 1,206New England352 (1) 351 367 — 367New York356 (10) 346 222 (4) 218ERCOT207 — 207 194 (2) 192Other Power Regions232 (9) 223 310 (21) 289Total Revenues for Reportable Segments3,655 (29) 3,626 3,663 (45) 3,618Other(b)(66) 29 (37) 569 45 614Total Generation Consolidated Operating Revenues$3,589 $— $3,589 $4,232 $— $4,232
[8]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmYxYjEyZjM4YzVjZDQ2YTM5N2E5NDQ4NWM2Nzk3Yjg1fFRleHRTZWxlY3Rpb246N0MwQjhEMjI5NzREODVBMzQxQjhDNTVBNUYzRTA3MDcM}

Uncategorized Items - exc-20160

Label	Element	Value
Pepco Holdings LLC [Member] | Predecessor [Member]
Payments of Ordinary Dividends, Common Stock	us-gaap_PaymentsOfDividendsCommonStock	$ 0
Cash and Cash Equivalents, Period Increase (Decrease)	us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease	293,000,000
Proceeds from Issuance of Preferred Stock and Preference Stock	us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock	0
Payments for (Proceeds from) Other Investing Activities	us-gaap_PaymentsForProceedsFromOtherInvestingActivities	5,000,000
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan	us-gaap_ProceedsFromIssuanceOfCommonStockDividendReinvestmentPlan	2,000,000
Proceeds from (Payments for) Other Financing Activities	us-gaap_ProceedsFromPaymentsForOtherFinancingActivities	2,000,000
Proceeds from Issuance of Long-term Debt	us-gaap_ProceedsFromIssuanceOfLongTermDebt	0
Change in Exelon intercompany money pool borrowings	exc_ChangeInExelonIntercompanyMoneyPoolBorrowings	0
Increase (Decrease) in Income Taxes Payable	us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable	12,000,000
Increase (Decrease) in Accounts Payable and Accrued Liabilities	us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	42,000,000
Other Noncash Income (Expense)	us-gaap_OtherNoncashIncomeExpense	(46,000,000)
Increase Decrease In Counterparty Collateral Net	exc_IncreaseDecreaseInCounterpartyCollateralNet	(1,000,000)
Repayments of Long-term Debt	us-gaap_RepaymentsOfLongTermDebt	11,000,000
Pension and Other Postretirement Benefit Contributions	us-gaap_PensionAndOtherPostretirementBenefitContributions	4,000,000
Increase (Decrease) in Restricted Cash	us-gaap_IncreaseDecreaseInRestrictedCash	(3,000,000)
Distribution to members	exc_DistributionToMembers	0
Change Receivables Payables From Affiliates	exc_ChangeReceivablesPayablesFromAffiliates	0
Unrealized Gain (Loss) on Derivatives	us-gaap_UnrealizedGainLossOnDerivatives	(18,000,000)
Net Cash Provided by (Used in) Investing Activities	us-gaap_NetCashProvidedByUsedInInvestingActivities	(343,000,000)
Proceeds from (Repayments of) Short-term Debt, Maturing in Three Months or Less	us-gaap_ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	(121,000,000)
Proceeds from Short-term Debt, Maturing in More than Three Months	us-gaap_ProceedsFromShortTermDebtMaturingInMoreThanThreeMonths	500,000,000
Increase (Decrease) in Receivables	us-gaap_IncreaseDecreaseInReceivables	28,000,000
Deferred Income Taxes and Tax Credits	us-gaap_DeferredIncomeTaxesAndTaxCredits	19,000,000
Increase (Decrease) in Inventories	us-gaap_IncreaseDecreaseInInventories	4,000,000
Payments to Acquire Marketable Securities	us-gaap_PaymentsToAcquireMarketableSecurities	68,000,000
Payments to Acquire Property, Plant, and Equipment	us-gaap_PaymentsToAcquirePropertyPlantAndEquipment	273,000,000
Pepco Holdings LLC [Member] | Successor [Member]
Payments of Ordinary Dividends, Common Stock	us-gaap_PaymentsOfDividendsCommonStock	0
Cash and Cash Equivalents, Period Increase (Decrease)	us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease	(25,000,000)
Proceeds from Issuance of Preferred Stock and Preference Stock	us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock	0
Payments for (Proceeds from) Other Investing Activities	us-gaap_PaymentsForProceedsFromOtherInvestingActivities	(8,000,000)
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan	us-gaap_ProceedsFromIssuanceOfCommonStockDividendReinvestmentPlan	0
Proceeds from (Payments for) Other Financing Activities	us-gaap_ProceedsFromPaymentsForOtherFinancingActivities	(3,000,000)
Proceeds from Issuance of Long-term Debt	us-gaap_ProceedsFromIssuanceOfLongTermDebt	1,000,000
Change in Exelon intercompany money pool borrowings	exc_ChangeInExelonIntercompanyMoneyPoolBorrowings	28,000,000
Increase (Decrease) in Income Taxes Payable	us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable	22,000,000
Repayments of Debt, Maturing in More than Three Months	us-gaap_RepaymentsOfDebtMaturingInMoreThanThreeMonths	300,000,000
Increase (Decrease) in Accounts Payable and Accrued Liabilities	us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	(35,000,000)
Other Noncash Income (Expense)	us-gaap_OtherNoncashIncomeExpense	(444,000,000)
Increase Decrease In Counterparty Collateral Net	exc_IncreaseDecreaseInCounterpartyCollateralNet	0
Repayments of Long-term Debt	us-gaap_RepaymentsOfLongTermDebt	16,000,000
Pension and Other Postretirement Benefit Contributions	us-gaap_PensionAndOtherPostretirementBenefitContributions	2,000,000
Increase (Decrease) in Restricted Cash	us-gaap_IncreaseDecreaseInRestrictedCash	34,000,000
Distribution to members	exc_DistributionToMembers	(124,000,000)
Change Receivables Payables From Affiliates	exc_ChangeReceivablesPayablesFromAffiliates	39,000,000
Unrealized Gain (Loss) on Derivatives	us-gaap_UnrealizedGainLossOnDerivatives	0
Net Cash Provided by (Used in) Investing Activities	us-gaap_NetCashProvidedByUsedInInvestingActivities	(350,000,000)
Proceeds from (Repayments of) Short-term Debt, Maturing in Three Months or Less	us-gaap_ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	(537,000,000)
Proceeds from Short-term Debt, Maturing in More than Three Months	us-gaap_ProceedsFromShortTermDebtMaturingInMoreThanThreeMonths	0
Increase (Decrease) in Receivables	us-gaap_IncreaseDecreaseInReceivables	(56,000,000)
Deferred Income Taxes and Tax Credits	us-gaap_DeferredIncomeTaxesAndTaxCredits	(16,000,000)
Increase (Decrease) in Inventories	us-gaap_IncreaseDecreaseInInventories	0
Proceeds from Sale of Property Held-for-sale	us-gaap_ProceedsFromSaleOfPropertyHeldForSale	15,000,000
Payments to Acquire Marketable Securities	us-gaap_PaymentsToAcquireMarketableSecurities	0
Payments to Acquire Property, Plant, and Equipment	us-gaap_PaymentsToAcquirePropertyPlantAndEquipment	$ 339,000,000