Consolidated Edison Co Of New York 10-Q 2 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 31, 2017
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Trading Symbol	ED
Entity Registrant Name	CONSOLIDATED EDISON INC
Entity Central Index Key	1,047,862
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		310,068,797
CECONY
Document Information [Line Items]
Entity Registrant Name	CONSOLIDATED EDISON CO OF NEW YORK INC
Entity Central Index Key	23,632
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer

Consolidated Income Statement (

Consolidated Income Statement (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
OPERATING REVENUES
Electric	$ 2,675	$ 2,769	$ 6,573	$ 6,717
Gas	296	235	1,593	1,246
Steam	62	63	448	406
Non-utility	178	350	458	999
TOTAL OPERATING REVENUES	3,211	3,417	9,072	9,368
OPERATING EXPENSES
Purchased power	460	798	1,253	2,047
Fuel	30	29	169	133
Gas purchased for resale	115	81	584	320
Other operations and maintenance	852	840	2,406	2,447
Depreciation and amortization	337	305	998	905
Taxes, other than income taxes	544	528	1,597	1,523
TOTAL OPERATING EXPENSES	2,338	2,581	7,007	7,375
Gain on sale of retail electric supply business and solar electric production project	0	104	1	104
OPERATING INCOME	873	940	2,066	2,097
OTHER INCOME (DEDUCTIONS)
Investment income	20	20	59	27
Other income	20	31	43	43
Allowance for equity funds used during construction	3	3	8	7
Other deductions	(4)	(5)	(12)	(16)
TOTAL OTHER INCOME	39	49	98	61
INCOME BEFORE INTEREST AND INCOME TAX EXPENSE	912	989	2,164	2,158
INTEREST EXPENSE
Interest on long-term debt	183	174	539	504
Other interest	4	5	11	17
Allowance for borrowed funds used during construction	(2)	(1)	(5)	(4)
NET INTEREST EXPENSE	185	178	545	517
INCOME BEFORE INCOME TAX EXPENSE	727	811	1,619	1,641
INCOME TAX EXPENSE	270	314	599	602
NET INCOME	$ 457	$ 497	$ 1,020	$ 1,039
Net income per common share-basic (dollars per share)	$ 1.48	$ 1.63	$ 3.33	$ 3.47
Net income per common share-diluted (dollars per share)	1.48	1.62	3.31	3.46
DIVIDENDS DECLARED PER COMMON SHARE (dollars per share)	$ 0.69	$ 0.67	$ 2.07	$ 2.01
AVERAGE NUMBER OF SHARES OUTSTANDING-BASIC (IN MILLIONS) (shares)	307.8	304.5	306.2	299.1
AVERAGE NUMBER OF SHARES OUTSTANDING—DILUTED (IN MILLIONS) (shares)	309.3	305.9	307.7	300.5
CECONY
OPERATING REVENUES
Electric	$ 2,469	$ 2,557	$ 6,079	$ 6,222
Gas	268	208	1,421	1,113
Steam	62	63	448	406
TOTAL OPERATING REVENUES	2,799	2,828	7,948	7,741
OPERATING EXPENSES
Purchased power	400	495	1,110	1,216
Fuel	30	29	169	133
Gas purchased for resale	58	34	372	217
Other operations and maintenance	691	724	1,992	2,105
Depreciation and amortization	300	278	891	825
Taxes, other than income taxes	520	502	1,523	1,446
TOTAL OPERATING EXPENSES	1,999	2,062	6,057	5,942
OPERATING INCOME	800	766	1,891	1,799
OTHER INCOME (DEDUCTIONS)
Investment income	2	4	9	6
Allowance for equity funds used during construction	3	2	7	6
Other deductions	(5)	(4)	(10)	(10)
TOTAL OTHER INCOME	0	2	6	2
INCOME BEFORE INTEREST AND INCOME TAX EXPENSE	800	768	1,897	1,801
INTEREST EXPENSE
Interest on long-term debt	155	150	456	440
Other interest	4	5	11	14
Allowance for borrowed funds used during construction	(2)	(1)	(4)	(3)
NET INTEREST EXPENSE	157	154	463	451
INCOME BEFORE INCOME TAX EXPENSE	643	614	1,434	1,350
INCOME TAX EXPENSE	242	226	551	491
NET INCOME	$ 401	$ 388	$ 883	$ 859

Consolidated Statement of Compr

Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
NET INCOME	$ 457	$ 497	$ 1,020	$ 1,039
OTHER COMPREHENSIVE INCOME, NET OF TAXES
Pension and other postretirement benefit plan liability adjustments, net of taxes	1	1	1	2
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	1	1	1	2
COMPREHENSIVE INCOME	458	498	1,021	1,041
CECONY
NET INCOME	401	388	883	859
OTHER COMPREHENSIVE INCOME, NET OF TAXES
Pension and other postretirement benefit plan liability adjustments, net of taxes	1	0	1	1
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	1	0	1	1
COMPREHENSIVE INCOME	$ 402	$ 388	$ 884	$ 860

Consolidated Statement of Cash

Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
OPERATING ACTIVITIES
Net income	$ 1,020	$ 1,039
PRINCIPAL NON-CASH CHARGES/(CREDITS) TO INCOME
Depreciation and amortization	998	905
Deferred income taxes	626	524
Rate case amortization and accruals	(93)	(157)
Common equity component of allowance for funds used during construction	(8)	(7)
Net derivative gains	(4)	(7)
Gain on sale of retail electric supply business and solar electric production project	(1)	(104)
Other non-cash items, net	(1)	99
CHANGES IN ASSETS AND LIABILITIES
Accounts receivable – customers	1	(138)
Materials and supplies, including fuel oil and gas in storage	2	15
Other receivables and other current assets	(39)	90
Income taxes receivable	33	100
Prepayments	(433)	(403)
Accounts payable	(54)	142
Pensions and retiree benefits obligations, net	305	464
Pensions and retiree benefits contributions	(462)	(510)
Accrued taxes	(21)	(21)
Accrued interest	59	66
Superfund and environmental remediation costs, net	(9)	68
Distributions from equity investments	87	45
System benefit charge	194	193
Deferred charges, noncurrent assets and other regulatory assets	(18)	(104)
Deferred credits and other regulatory liabilities	(40)	116
Other current and noncurrent liabilities	85	(79)
NET CASH FLOWS FROM OPERATING ACTIVITIES	2,227	2,336
INVESTING ACTIVITIES
Utility construction expenditures	(2,148)	(2,057)
Cost of removal less salvage	(185)	(149)
Non-utility construction expenditures	(288)	(436)
Proceeds from the transfer of assets to NY Transco	0	122
Proceeds from sale of assets	34	250
Restricted cash	13	(21)
Other investing activities	32	(145)
NET CASH FLOWS USED IN INVESTING ACTIVITIES	(2,572)	(3,717)
FINANCING ACTIVITIES
Net payment of short-term debt	(698)	(928)
Issuance of long-term debt	997	1,765
Retirement of long-term debt	(429)	(407)
Debt issuance costs	(12)	(16)
Common stock dividends	(600)	(570)
Issuance of common shares - public offering	343	702
Issuance of common shares for stock plans	37	38
Distribution to noncontrolling interest	0	(1)
NET CASH FLOWS (USED IN)/FROM FINANCING ACTIVITIES	(362)	583
CASH AND TEMPORARY CASH INVESTMENTS:
NET CHANGE FOR THE PERIOD	(707)	(798)
BALANCE AT BEGINNING OF PERIOD	776	944
BALANCE AT END OF PERIOD	69	146
LESS: CHANGE IN CASH BALANCES HELD FOR SALE	0	(4)
BALANCE AT END OF PERIOD EXCLUDING HELD FOR SALE	69	150
Cash paid/(received) during the period for:
Interest	479	437
Income taxes	(34)	(144)
SUPPLEMENTAL DISCLOSURE OF NON-CASH INFORMATION
Construction expenditures in accounts payable	352	242
Issuance of common shares for dividend reinvestment	35	35
Electric and Gas Transmission Projects
INVESTING ACTIVITIES
Investments in/acquisitions of projects	(29)	(1,040)
Renewable Electric Production Projects
INVESTING ACTIVITIES
Investments in/acquisitions of projects	(1)	(241)
CECONY
OPERATING ACTIVITIES
Net income	883	859
PRINCIPAL NON-CASH CHARGES/(CREDITS) TO INCOME
Depreciation and amortization	891	825
Deferred income taxes	566	569
Rate case amortization and accruals	(107)	(170)
Common equity component of allowance for funds used during construction	(7)	(6)
Other non-cash items, net	(14)	7
CHANGES IN ASSETS AND LIABILITIES
Accounts receivable – customers	18	(79)
Materials and supplies, including fuel oil and gas in storage	(18)	15
Other receivables and other current assets	29	18
Accounts receivable from affiliated companies	12	38
Prepayments	(398)	(351)
Accounts payable	(20)	82
Accounts payable to affiliated companies	1	8
Pensions and retiree benefits obligations, net	274	439
Pensions and retiree benefits contributions	(416)	(472)
Accrued taxes	(18)	(17)
Accrued interest	61	43
Superfund and environmental remediation costs, net	(7)	76
System benefit charge	175	176
Accrued taxes to affiliated companies	(119)	(2)
Deferred charges, noncurrent assets and other regulatory assets	(60)	(153)
Deferred credits and other regulatory liabilities	77	165
Other current and noncurrent liabilities	(13)	(53)
NET CASH FLOWS FROM OPERATING ACTIVITIES	1,790	2,017
INVESTING ACTIVITIES
Utility construction expenditures	(2,020)	(1,932)
Cost of removal less salvage	(179)	(146)
Proceeds from the transfer of assets to NY Transco	0	122
Restricted cash	2	13
NET CASH FLOWS USED IN INVESTING ACTIVITIES	(2,197)	(1,943)
FINANCING ACTIVITIES
Net payment of short-term debt	(453)	(553)
Issuance of long-term debt	500	550
Retirement of long-term debt	0	(400)
Debt issuance costs	(7)	(6)
Capital contribution by parent	279	76
Dividend to parent	(597)	(558)
NET CASH FLOWS (USED IN)/FROM FINANCING ACTIVITIES	(278)	(891)
CASH AND TEMPORARY CASH INVESTMENTS:
NET CHANGE FOR THE PERIOD	(685)	(817)
BALANCE AT BEGINNING OF PERIOD	702	843
BALANCE AT END OF PERIOD	17	26
BALANCE AT END OF PERIOD EXCLUDING HELD FOR SALE	17
Cash paid/(received) during the period for:
Interest	388	386
Income taxes	96	(130)
SUPPLEMENTAL DISCLOSURE OF NON-CASH INFORMATION
Construction expenditures in accounts payable	$ 240	$ 195

Consolidated Balance Sheet (Una

Consolidated Balance Sheet (Unaudited) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
CURRENT ASSETS
Cash and temporary cash investments	$ 69	$ 776
Accounts receivable - customers, less allowance for uncollectible accounts	1,111	1,106
Other receivables, less allowance for uncollectible accounts	181	195
Income taxes receivable	46	79
Accrued unbilled revenue	411	447
Fuel oil, gas in storage, materials and supplies, at average cost	337	339
Prepayments	592	159
Regulatory assets	109	100
Restricted cash	41	54
Other current assets	199	151
TOTAL CURRENT ASSETS	3,096	3,406
INVESTMENTS	1,977	1,921
UTILITY PLANT, AT ORIGINAL COST
General	2,891	2,719
TOTAL	41,916	40,411
Less: Accumulated depreciation	8,904	8,541
Net	33,012	31,870
Construction work in progress	1,415	1,175
NET UTILITY PLANT	34,427	33,045
NON-UTILITY PLANT
Non-utility property, less accumulated depreciation	1,686	1,482
Construction work in progress	615	689
NET PLANT	36,728	35,216
OTHER NONCURRENT ASSETS
Goodwill	428	428
Intangible assets, less accumulated amortization of $12 and $6 in 2017 and 2016, respectively	114	124
Regulatory assets	6,769	7,024
Other deferred charges and noncurrent assets	134	136
TOTAL OTHER NONCURRENT ASSETS	7,445	7,712
TOTAL ASSETS	49,246	48,255
CURRENT LIABILITIES
Long-term debt due within one year	687	39
Notes payable	356	1,054
Accounts payable	1,057	1,147
Customer deposits	344	352
Accrued taxes	43	64
Accrued interest	209	150
Accrued wages	105	101
Fair value of derivative liabilities	70	77
Regulatory liabilities	58	128
System benefit charge	628	434
Other current liabilities	358	297
TOTAL CURRENT LIABILITIES	3,915	3,843
NONCURRENT LIABILITIES
Provision for injuries and damages	164	160
Pensions and retiree benefits	1,443	1,847
Superfund and other environmental costs	745	753
Asset retirement obligations	256	246
Fair value of derivative liabilities	83	40
Deferred income taxes and unamortized investment tax credits	10,744	10,205
Regulatory liabilities	1,873	1,905
Other deferred credits and noncurrent liabilities	262	215
TOTAL NONCURRENT LIABILITIES	15,570	15,371
LONG-TERM DEBT	14,651	14,735
EQUITY
Common shareholders’ equity	15,102	14,298
Noncontrolling interest	8	8
TOTAL EQUITY (See Statement of Equity)	15,110	14,306
TOTAL LIABILITIES AND EQUITY	49,246	48,255
Electric
UTILITY PLANT, AT ORIGINAL COST
Utility plant, at original cost	28,595	27,747
Gas
UTILITY PLANT, AT ORIGINAL COST
Utility plant, at original cost	7,972	7,524
Steam
UTILITY PLANT, AT ORIGINAL COST
Utility plant, at original cost	2,458	2,421
CECONY
CURRENT ASSETS
Cash and temporary cash investments	17	702
Accounts receivable - customers, less allowance for uncollectible accounts	1,021	1,032
Other receivables, less allowance for uncollectible accounts	85	81
Accrued unbilled revenue	382	399
Accounts receivable from affiliated companies	97	109
Fuel oil, gas in storage, materials and supplies, at average cost	288	270
Prepayments	498	100
Regulatory assets	100	90
Restricted cash	0	2
Other current assets	62	95
TOTAL CURRENT ASSETS	2,550	2,880
INVESTMENTS	370	315
UTILITY PLANT, AT ORIGINAL COST
General	2,640	2,490
TOTAL	39,257	37,847
Less: Accumulated depreciation	8,170	7,836
Net	31,087	30,011
Construction work in progress	1,327	1,104
NET UTILITY PLANT	32,414	31,115
NON-UTILITY PLANT
Non-utility property, less accumulated depreciation	4	4
NET PLANT	32,418	31,119
OTHER NONCURRENT ASSETS
Regulatory assets	6,248	6,473
Other deferred charges and noncurrent assets	61	69
TOTAL OTHER NONCURRENT ASSETS	6,309	6,542
TOTAL ASSETS	41,647	40,856
CURRENT LIABILITIES
Long-term debt due within one year	600	0
Notes payable	147	600
Accounts payable	802	876
Accounts payable to affiliated companies	11	10
Customer deposits	332	336
Accrued taxes	32	50
Accrued taxes to affiliated companies	0	119
Accrued interest	172	111
Accrued wages	95	91
Fair value of derivative liabilities	59	66
Regulatory liabilities	38	90
System benefit charge	573	398
Other current liabilities	207	242
TOTAL CURRENT LIABILITIES	3,068	2,989
NONCURRENT LIABILITIES
Provision for injuries and damages	158	154
Pensions and retiree benefits	1,150	1,544
Superfund and other environmental costs	648	655
Asset retirement obligations	234	227
Fair value of derivative liabilities	73	33
Deferred income taxes and unamortized investment tax credits	10,060	9,450
Regulatory liabilities	1,673	1,712
Other deferred credits and noncurrent liabilities	217	190
TOTAL NONCURRENT LIABILITIES	14,213	13,965
LONG-TERM DEBT	11,971	12,073
EQUITY
Common shareholders’ equity	12,395	11,829
TOTAL LIABILITIES AND EQUITY	41,647	40,856
CECONY | Electric
UTILITY PLANT, AT ORIGINAL COST
Utility plant, at original cost	26,930	26,122
CECONY | Gas
UTILITY PLANT, AT ORIGINAL COST
Utility plant, at original cost	7,229	6,814
CECONY | Steam
UTILITY PLANT, AT ORIGINAL COST
Utility plant, at original cost	$ 2,458	$ 2,421

Consolidated Balance Sheet (Un6

Consolidated Balance Sheet (Unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Accounts receivable - customers, allowance for uncollectible accounts	$ 63	$ 69
Other receivables, allowance for uncollectible accounts	8	14
Non-utility property, accumulated depreciation	185	140
Intangible assets, accumulated amortization	12	6
CECONY
Accounts receivable - customers, allowance for uncollectible accounts	58	65
Other receivables, allowance for uncollectible accounts	7	13
Non-utility property, accumulated depreciation	$ 25	$ 25

Consolidated Statement of Equit

Consolidated Statement of Equity/Shareholder's Equity (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	Capital Stock Expense	Accumulated Other Comprehensive Income/(Loss)	Noncontrolling Interest	CECONY	CECONYCommon Stock	CECONYAdditional Paid-In Capital	CECONYRetained Earnings	CECONYRepurchased Con Edison Stock	CECONYCapital Stock Expense	CECONYAccumulated Other Comprehensive Income/(Loss)
Beginning Balance (in shares) at Dec. 31, 2015		293			23					235
Beginning Balance at Dec. 31, 2015	$ 13,061	$ 32	$ 5,030	$ 9,123	$ (1,038)	$ (61)	$ (34)	$ 9							$ (9)
Beginning Balance at Dec. 31, 2015									$ 11,415	$ 589	$ 4,247	$ 7,611	$ (962)	$ (61)	(9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	310			310					310			310
Common stock dividends	(197)			(197)					(186)			(186)
Issuance of common shares for stock plans (in shares)		1
Issuance of common shares for stock plans	28		28
Capital contribution by parent									23		23
Other comprehensive income (loss)	0								0						0
Noncontrolling interest	(1)							(1)
Ending Balance (in shares) at Mar. 31, 2016		294			23					235
Ending Balance at Mar. 31, 2016									11,562	$ 589	4,270	7,735	(962)	(61)	(9)
Ending Balance at Mar. 31, 2016	13,201	$ 32	5,058	9,236	$ (1,038)	(61)	(34)	8
Beginning Balance (in shares) at Dec. 31, 2015		293			23					235
Beginning Balance at Dec. 31, 2015	13,061	$ 32	5,030	9,123	$ (1,038)	(61)	(34)	9							(9)
Beginning Balance at Dec. 31, 2015									11,415	$ 589	4,247	7,611	(962)	(61)	(9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,039								859
Other comprehensive income (loss)	2								1
Ending Balance (in shares) at Sep. 30, 2016		305			23					235
Ending Balance at Sep. 30, 2016									11,793	$ 589	4,323	7,912	(962)	(61)	(8)
Ending Balance at Sep. 30, 2016	14,275	$ 33	5,830	9,557	$ (1,038)	(83)	(32)	8							(8)
Beginning Balance (in shares) at Mar. 31, 2016		294			23					235
Beginning Balance at Mar. 31, 2016	13,201	$ 32	5,058	9,236	$ (1,038)	(61)	(34)	8
Beginning Balance at Mar. 31, 2016									11,562	$ 589	4,270	7,735	(962)	(61)	(9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	232			232					161			161
Common stock dividends	(204)			(204)					(186)			(186)
Issuance of common shares for stock plans	26		26
Issuance of common shares - public offering (in shares)		10
Issuance of common shares - public offering	702	$ 1	723			(22)
Capital contribution by parent									28		28
Other comprehensive income (loss)	1						1		1						1
Ending Balance (in shares) at Jun. 30, 2016		304			23					235
Ending Balance at Jun. 30, 2016									11,566	$ 589	4,298	7,710	(962)	(61)	(8)
Ending Balance at Jun. 30, 2016	13,958	$ 33	5,807	9,264	$ (1,038)	(83)	(33)	8							(8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	497			497					388			388
Common stock dividends	(204)			(204)					(186)			(186)
Issuance of common shares for stock plans (in shares)		1
Issuance of common shares for stock plans	23		23
Capital contribution by parent									25		25
Other comprehensive income (loss)	1						1		0						0
Ending Balance (in shares) at Sep. 30, 2016		305			23					235
Ending Balance at Sep. 30, 2016									11,793	$ 589	4,323	7,912	(962)	(61)	(8)
Ending Balance at Sep. 30, 2016	14,275	$ 33	5,830	9,557	$ (1,038)	(83)	(32)	8							(8)
Beginning Balance (in shares) at Dec. 31, 2016		305			23					235
Beginning Balance at Dec. 31, 2016	14,306	$ 33	5,854	9,559	$ (1,038)	(83)	(27)	8							(7)
Beginning Balance at Dec. 31, 2016	14,298								11,829	$ 589	4,347	7,923	(962)	(61)	(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	388			388					339			339
Common stock dividends	(211)			(211)					(199)			(199)
Issuance of common shares for stock plans	24		24
Capital contribution by parent									22		22
Other comprehensive income (loss)	(1)						(1)		0						0
Ending Balance (in shares) at Mar. 31, 2017		305			23					235
Ending Balance at Mar. 31, 2017									11,991	$ 589	4,369	8,063	(962)	(61)	(7)
Ending Balance at Mar. 31, 2017	14,506	$ 33	5,878	9,736	$ (1,038)	(83)	(28)	8
Beginning Balance (in shares) at Dec. 31, 2016		305			23					235
Beginning Balance at Dec. 31, 2016	14,306	$ 33	5,854	9,559	$ (1,038)	(83)	(27)	8							(7)
Beginning Balance at Dec. 31, 2016	14,298								11,829	$ 589	4,347	7,923	(962)	(61)	(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,020								883
Other comprehensive income (loss)	1								1
Ending Balance (in shares) at Sep. 30, 2017		310			23					235
Ending Balance at Sep. 30, 2017	15,102								12,395	$ 589	4,627	8,209	(962)	(62)	(6)
Ending Balance at Sep. 30, 2017	15,110	$ 33	6,274	9,944	$ (1,038)	(85)	(26)	8							(6)
Beginning Balance (in shares) at Mar. 31, 2017		305			23					235
Beginning Balance at Mar. 31, 2017	14,506	$ 33	5,878	9,736	$ (1,038)	(83)	(28)	8
Beginning Balance at Mar. 31, 2017									11,991	$ 589	4,369	8,063	(962)	(61)	(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	175			175					143			143
Common stock dividends	(210)			(210)					(199)			(199)
Issuance of common shares for stock plans (in shares)		1
Issuance of common shares for stock plans	26		26
Capital contribution by parent									23		23
Other comprehensive income (loss)	1						1		0						0
Ending Balance (in shares) at Jun. 30, 2017		306			23					235
Ending Balance at Jun. 30, 2017									11,958	$ 589	4,392	8,007	(962)	(61)	(7)
Ending Balance at Jun. 30, 2017	14,498	$ 33	5,904	9,701	$ (1,038)	(83)	(27)	8							(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	457			457					401			401
Common stock dividends	(214)			(214)					(199)			(199)
Issuance of common shares for stock plans	25		25
Issuance of common shares - public offering (in shares)		4
Issuance of common shares - public offering	343		345			(2)
Capital contribution by parent									234		235			(1)
Other comprehensive income (loss)	1						1		1						1
Ending Balance (in shares) at Sep. 30, 2017		310			23					235
Ending Balance at Sep. 30, 2017	15,102								$ 12,395	$ 589	$ 4,627	$ 8,209	$ (962)	$ (62)	(6)
Ending Balance at Sep. 30, 2017	$ 15,110	$ 33	$ 6,274	$ 9,944	$ (1,038)	$ (85)	$ (26)	$ 8							$ (6)

General

General	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
General	General These combined notes accompany and form an integral part of the separate consolidated financial statements of each of the two separate registrants: Consolidated Edison, Inc. and its subsidiaries (Con Edison) and Consolidated Edison Company of New York, Inc. and its subsidiaries (CECONY). CECONY is a subsidiary of Con Edison and as such its financial condition and results of operations and cash flows, which are presented separately in the CECONY consolidated financial statements, are also consolidated, along with those of Orange and Rockland Utilities, Inc. (O&R), Con Edison Clean Energy Businesses, Inc. (together with its subsidiaries, the Clean Energy Businesses) and Con Edison Transmission, Inc. (together with its subsidiaries, Con Edison Transmission) in Con Edison’s consolidated financial statements. The term “Utilities” is used in these notes to refer to CECONY and O&R. As used in these notes, the term “Companies” refers to Con Edison and CECONY and, except as otherwise noted, the information in these combined notes relates to each of the Companies. However, CECONY makes no representation as to information relating to Con Edison or the subsidiaries of Con Edison other than itself. The separate interim consolidated financial statements of each of the Companies are unaudited but, in the opinion of their respective managements, reflect all adjustments (which include only normally recurring adjustments) necessary for a fair presentation of the results for the interim periods presented. The Companies’ separate interim consolidated financial statements should be read together with their separate audited financial statements (including the combined notes thereto) included in Item 8 of their combined Annual Report on Form 10-K for the year ended December 31, 2016 and their separate unaudited financial statements (including the combined notes thereto) included in Part 1, Item 1 of their combined Quarterly Report on Form 10-Q for the quarterly periods ended March 31, 2017 and June 30, 2017 . Certain prior period amounts have been reclassified to conform to the current period presentation. Con Edison has two regulated utility subsidiaries: CECONY and O&R. CECONY provides electric service and gas service in New York City and Westchester County. The company also provides steam service in parts of Manhattan. O&R, along with its regulated utility subsidiary, provides electric service in southeastern New York and northern New Jersey and gas service in southeastern New York. Con Edison Clean Energy Businesses, Inc. has three subsidiaries: Consolidated Edison Development, Inc. (Con Edison Development), a company that develops, owns and operates renewable and energy infrastructure projects; Consolidated Edison Energy, Inc. (Con Edison Energy), a company that provides energy-related products and services to wholesale customers; and Consolidated Edison Solutions, Inc. (Con Edison Solutions), a company that provides energy-related products and services to retail customers. Con Edison Transmission, Inc. invests in electric transmission facilities through its subsidiary, Consolidated Edison Transmission, LLC (CET Electric), and invests in gas pipeline and storage facilities through its subsidiary Con Edison Gas Pipeline and Storage, LLC (CET Gas).

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Earnings Per Common Share Con Edison presents basic and diluted earnings per share (EPS) on the face of its consolidated income statement. Basic EPS is calculated by dividing earnings available to common shareholders (“Net income” on Con Edison’s consolidated income statement) by the weighted average number of Con Edison common shares outstanding during the period. In the calculation of diluted EPS, weighted average shares outstanding are increased for additional shares that would be outstanding if potentially dilutive securities were converted to common stock. Potentially dilutive securities for Con Edison consist of restricted stock units, deferred stock units and stock options for which the average market price of the common shares for the period was greater than the exercise price. For the three and nine months ended September 30, 2017 and 2016 , basic and diluted EPS for Con Edison are calculated as follows: For the Three Months Ended September 30, For the Nine Months Ended September 30, (Millions of Dollars, except per share amounts/Shares in Millions) 2017 2016 2017 2016 Net income $457 $497 $1,020 $1,039 Weighted average common shares outstanding – basic 307.8 304.5 306.2 299.1 Add: Incremental shares attributable to effect of potentially dilutive securities 1.5 1.4 1.5 1.4 Adjusted weighted average common shares outstanding – diluted 309.3 305.9 307.7 300.5 Net Income per common share – basic $1.48 $1.63 $3.33 $3.47 Net Income per common share – diluted $1.48 $1.62 $3.31 $3.46 Changes in Accumulated Other Comprehensive Income/(Loss) by Component For the three and nine months ended September 30, 2017 and 2016 , changes to accumulated other comprehensive income/(loss) (OCI) for Con Edison and CECONY are as follows: For the Three Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Beginning balance, accumulated OCI, net of taxes (a) $(27) $(33) $(7) $(8) Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax of $(1) for Con Edison in 2017 and 2016 (a)(b) 1 1 1 — Current period OCI, net of taxes 1 1 1 — Ending balance, accumulated OCI, net of taxes $(26) $(32) $(6) $(8) For the Nine Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Beginning balance, accumulated OCI, net of taxes (a) $(27) $(34) $(7) $(9) OCI before reclassifications, net of tax of $1 for Con Edison in 2017 and 2016 (2) (1) — — Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax of $(2) for Con Edison in 2017 and 2016 (a)(b) 3 3 1 1 Current period OCI, net of taxes 1 2 1 1 Ending balance, accumulated OCI, net of taxes $(26) $(32) $(6) $(8) (a) Tax reclassified from accumulated OCI is reported in the income tax expense line item of the consolidated income statement. (b) For the portion of unrecognized pension and other postretirement benefit costs relating to the Utilities, costs are recorded into, and amortized out of, regulatory assets instead of OCI. The net actuarial losses and prior service costs recognized during the period are included in the computation of total periodic pension and other postretirement benefit cost. See Notes E and F.

Regulatory Matters

Regulatory Matters	9 Months Ended
	Sep. 30, 2017
Regulated Operations [Abstract]
Regulatory Matters	Regulatory Matters Rate Plans Rockland Electric Company (RECO) In February 2017, the New Jersey Board of Public Utilities (NJBPU) approved a stipulation of settlement for a RECO electric rate plan commencing March 2017. The following table contains a summary of the electric rate plan. RECO Effective period March 2017 (a) Base rate changes Yr. 1 - $1.7 million Amortization to income of net regulatory (assets) and liabilities $0.2 million over three years and continuation of $(25.6) million of deferred storm costs over four years expiring July 31, 2018 (b) Recoverable energy costs Current rate recovery of purchased power costs. Cost reconciliations None Average rate base Yr. 1 - $178.7 million Weighted average cost of capital (after-tax) 7.47 percent Authorized return on common equity 9.6 percent Cost of long-term debt 5.37 percent Common equity ratio 49.7 percent (a) Effective until a new rate plan approved by the NJBPU goes into effect. (b) In January 2016, the NJBPU approved RECO’s plan to spend $15.7 million in capital over three years to harden its electric system against storms, the costs of which RECO, beginning in 2017, is collecting through a customer surcharge. In September 2017, RECO, the New Jersey Division of Rate Counsel and the New Jersey Board of Public Utilities entered into a settlement agreement, which is subject to FERC approval, that increases RECO's annual transmission revenue requirement from $11.8 million to $17.7 million , effective April 2017. The revenue requirement reflects a return on common equity of 10.0 percent . Other Regulatory Matters On August 16, 2017, the New York State Public Service Commission (NYSPSC) issued an order in its proceeding investigating an April 21, 2017 Metropolitan Transportation Authority (MTA) subway power outage. The order indicated that the investigation determined that the outage was caused by a failure of CECONY’s electricity supply to a subway station, which led to a loss of the subway signals, and that one of the secondary services to the MTA facility had been improperly rerouted and was not properly documented by the company. The order also indicated that the loss of power to the subway station affected multiple subway lines and caused widespread delays across the subway system. Pursuant to the order, the company is required to take certain actions, including performing inspections of electrical equipment that serves the MTA system, analyzing power supply and power quality events affecting the MTA’s signaling services, providing new monitoring and other equipment and filing monthly reports with the NYSPSC on all of the company's activities related to the MTA system. In July 2017, the Chairman of the NYSPSC notified the company that the April 21, 2017 subway power outage incident will likely result in a prudence review of the reasonableness of CECONY's actions and conduct. The order did not commence a prudence review or address cost recovery. Under the New York State Administrative Procedure Act, the order could not remain in effect for more than 90 days without further action by the NYSPSC because it was adopted on an emergency basis. At its October 19, 2017 meeting, the NYSPSC approved another order in this proceeding. The NYSPSC has not yet issued this other order. The company is unable to estimate the amount or range of its possible costs related to this matter. Regulatory Assets and Liabilities Regulatory assets and liabilities at September 30, 2017 and December 31, 2016 were comprised of the following items: Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Regulatory assets Unrecognized pension and other postretirement costs $2,626 $2,874 $2,476 $2,730 Future income tax 2,419 2,439 2,308 2,325 Environmental remediation costs 803 823 690 711 Revenue taxes 341 295 325 280 Deferred derivative losses 88 48 78 42 Pension and other postretirement benefits deferrals 70 38 45 7 Municipal infrastructure support costs 57 44 57 44 Deferred storm costs 43 56 — 3 Unamortized loss on reacquired debt 39 43 37 41 Indian Point Energy Center program costs 32 50 32 50 O&R property tax reconciliation 29 37 — — Brooklyn Queens demand management program 28 29 28 29 Preferred stock redemption 24 25 24 25 Surcharge for New York State assessment 18 28 16 26 Net electric deferrals 13 24 13 24 Workers’ compensation 12 13 12 13 O&R transition bond charges 10 15 — — Recoverable energy costs 4 42 4 38 Other 113 101 103 85 Regulatory assets – noncurrent 6,769 7,024 6,248 6,473 Deferred derivative losses 81 91 75 86 Recoverable energy costs 28 9 25 4 Regulatory assets – current 109 100 100 90 Total Regulatory Assets $6,878 $7,124 $6,348 $6,563 Regulatory liabilities Allowance for cost of removal less salvage $798 $755 $671 $641 Pension and other postretirement benefit deferrals 202 193 174 162 Net unbilled revenue deferrals 166 145 166 145 Property tax reconciliation 140 178 140 178 Unrecognized other postretirement costs 84 60 84 60 Settlement of prudence proceeding 73 95 73 95 Carrying charges on repair allowance and bonus depreciation 49 68 48 67 New York State income tax rate change 48 61 48 60 Variable-rate tax-exempt debt – cost rate reconciliation 36 55 32 48 Property tax refunds 28 1 28 1 Settlement of gas proceedings 27 27 27 27 Base rate change deferrals 26 40 26 40 Earnings sharing - electric, gas and steam 24 39 15 28 Net utility plant reconciliations 11 16 8 15 Other 161 172 133 145 Regulatory liabilities – noncurrent 1,873 1,905 1,673 1,712 Refundable energy costs 29 29 9 5 Revenue decoupling mechanism 27 71 27 61 Deferred derivative gains 2 28 2 24 Regulatory liabilities – current 58 128 38 90 Total Regulatory Liabilities $1,931 $2,033 $1,711 $1,802

Capitalization

Capitalization	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Capitalization	Capitalization In March 2017, Con Edison issued $400 million aggregate principal amount of 2.00 percent debentures, due 2020, and prepaid the $400 million variable rate term loan that was to mature in 2018. Also, in March 2017, a Con Edison Development subsidiary issued $97 million aggregate principal amount of 4.45 percent senior notes, due 2042, secured by the company’s Upton County Solar project. In June 2017, CECONY issued $500 million aggregate principal amount of 3.875 percent debentures, due 2047. In August 2017, Con Edison issued 4.1 million common shares resulting in net proceeds of $343 million , after issuance expenses, that were invested by Con Edison in its subsidiaries, principally CECONY and the Clean Energy Businesses, for funding of their construction expenditures and for other general corporate purposes. The carrying amounts and fair values of long-term debt at September 30, 2017 and December 31, 2016 were: (Millions of Dollars) 2017 2016 Long-Term Debt (including current portion) (a) Carrying Amount Fair Value Carrying Amount Fair Value Con Edison $15,338 $17,195 $14,774 $16,093 CECONY $12,571 $14,213 $12,073 $13,268 (a) Amounts shown are net of unamortized debt expense and unamortized debt discount of $137 million and $115 million for Con Edison and CECONY, respectively, as of September 30, 2017 and $134 million and $113 million for Con Edison and CECONY, respectively, as of December 31, 2016 . Fair values of long-term debt have been estimated primarily using available market information. For Con Edison, $16,559 million and $636 million of the fair value of long-term debt at September 30, 2017 are classified as Level 2 and Level 3, respectively. For CECONY, $13,577 million and $636 million of the fair value of long-term debt at September 30, 2017 are classified as Level 2 and Level 3, respectively (see Note L). The $636 million of long-term debt classified as Level 3 is CECONY’s tax-exempt, auction-rate securities for which the market is highly illiquid and there is a lack of observable inputs.

Short-Term Borrowing

Short-Term Borrowing	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Short-Term Borrowing	Short-Term Borrowing At September 30, 2017 , Con Edison had $356 million of commercial paper outstanding of which $147 million was outstanding under CECONY’s program. The weighted average interest rate at September 30, 2017 was 1.3 percent for both Con Edison and CECONY. At December 31, 2016 , Con Edison had $1,054 million of commercial paper outstanding of which $600 million was outstanding under CECONY’s program. The weighted average interest rate at December 31, 2016 was 1.0 percent for both Con Edison and CECONY. At September 30, 2017 and December 31, 2016 , no loans were outstanding under the credit agreement (Credit Agreement). An immaterial amount and $2 million (including $2 million for CECONY) of letters of credit were outstanding under the Credit Agreement as of September 30, 2017 and December 31, 2016 , respectively.

Pension Benefits

Pension Benefits	9 Months Ended
	Sep. 30, 2017
Retirement Benefits [Abstract]
Pension Benefits	Pension Benefits Total Periodic Benefit Cost The components of the Companies’ total periodic benefit costs for the three and nine months ended September 30, 2017 and 2016 were as follows: For the Three Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Service cost – including administrative expenses $66 $69 $61 $65 Interest cost on projected benefit obligation 148 149 139 140 Expected return on plan assets (243) (237) (229) (225) Recognition of net actuarial loss 149 149 141 141 Recognition of prior service costs (4) 1 (5) — TOTAL PERIODIC BENEFIT COST $116 $131 $107 $121 Cost capitalized (40) (51) (37) (49) Reconciliation to rate level (14) 10 (16) 13 Cost charged to operating expenses $62 $90 $54 $85 For the Nine Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Service cost – including administrative expenses $197 $207 $184 $194 Interest cost on projected benefit obligation 444 447 416 419 Expected return on plan assets (726) (711) (689) (674) Recognition of net actuarial loss 446 447 423 424 Recognition of prior service costs (13) 3 (14) 1 TOTAL PERIODIC BENEFIT COST $348 $393 $320 $364 Cost capitalized (134) (157) (125) (148) Reconciliation to rate level (28) 35 (32) 39 Cost charged to operating expenses $186 $271 $163 $255 Expected Contributions Based on estimates as of September 30, 2017 , the Companies expect to make contributions to the pension plans during 2017 of $450 million (of which $412 million is to be contributed by CECONY). The Companies’ policy is to fund the total periodic benefit cost of the qualified plan to the extent tax deductible and to also contribute to the non-qualified supplemental plans. During the first nine months of 2017 , the Companies contributed $446 million to the pension plans (of which $409 million was contributed by CECONY). CECONY also contributed $14 million to its external trust for supplemental plans.

Other Postretirement Benefits

Other Postretirement Benefits	9 Months Ended
	Sep. 30, 2017
Retirement Benefits [Abstract]
Other Postretirement Benefits	Other Postretirement Benefits Total Periodic Benefit Cost The components of the Companies’ total periodic other postretirement benefit costs for the three and nine months ended September 30, 2017 and 2016 were as follows: For the Three Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Service cost $5 $4 $3 $3 Interest cost on accumulated other postretirement benefit obligation 11 12 9 10 Expected return on plan assets (17) (19) (15) (17) Recognition of net actuarial loss 1 1 — 1 Recognition of prior service cost (5) (5) (3) (3) TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST $(5) $(7) $(6) $(6) Cost capitalized 2 2 2 2 Reconciliation to rate level (1) 7 — 6 Cost charged to operating expenses $(4) $2 $(4) $2 For the Nine Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Service cost $15 $13 $10 $10 Interest cost on accumulated other postretirement benefit obligation 34 36 28 30 Expected return on plan assets (52) (58) (45) (50) Recognition of net actuarial loss/(gain) 2 4 (2) 2 Recognition of prior service cost (13) (15) (9) (11) TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST $(14) $(20) $(18) $(19) Cost capitalized 6 5 7 5 Reconciliation to rate level (3) 20 (1) 19 Cost charged to operating expenses $(11) $5 $(12) $5 Contributions During the first nine months of 2017, Con Edison contributed $16 million , of which $8 million was contributed by CECONY, to the other postretirement benefit plans. The Companies' policy is to fund the total periodic benefit cost of the plans to the extent tax deductible.

Environmental Matters

Environmental Matters	9 Months Ended
	Sep. 30, 2017
Environmental Remediation Obligations [Abstract]
Environmental Matters	Environmental Matters Superfund Sites Hazardous substances, such as asbestos, polychlorinated biphenyls (PCBs) and coal tar, have been used or generated in the course of operations of the Utilities and their predecessors and are present at sites and in facilities and equipment they currently or previously owned, including sites at which gas was manufactured or stored. The Federal Comprehensive Environmental Response, Compensation and Liability Act of 1980 and similar state statutes (Superfund) impose joint and several liability, regardless of fault, upon generators of hazardous substances for investigation and remediation costs (which include costs of demolition, removal, disposal, storage, replacement, containment and monitoring) and natural resource damages. Liability under these laws can be material and may be imposed for contamination from past acts, even though such past acts may have been lawful at the time they occurred. The sites at which the Utilities have been asserted to have liability under these laws, including their manufactured gas plant sites and any neighboring areas to which contamination may have migrated, are referred to herein as “Superfund Sites.” For Superfund Sites where there are other potentially responsible parties and the Utilities are not managing the site investigation and remediation, the accrued liability represents an estimate of the amount the Utilities will need to pay to investigate and, where determinable, discharge their related obligations. For Superfund Sites (including the manufactured gas plant sites) for which one of the Utilities is managing the investigation and remediation, the accrued liability represents an estimate of the company’s share of the undiscounted cost to investigate the sites and, for sites that have been investigated in whole or in part, the cost to remediate the sites, if remediation is necessary and if a reasonable estimate of such cost can be made. Remediation costs are estimated in light of the information available, applicable remediation standards and experience with similar sites. The accrued liabilities and regulatory assets related to Superfund Sites at September 30, 2017 and December 31, 2016 were as follows: Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Accrued Liabilities: Manufactured gas plant sites $659 $664 $563 $567 Other Superfund Sites 86 89 85 88 Total $745 $753 $648 $655 Regulatory assets $803 $823 $690 $711 Most of the accrued Superfund Site liability relates to sites that have been investigated, in whole or in part. However, for some of the sites, the extent and associated cost of the required remediation has not yet been determined. As investigations progress and information pertaining to the required remediation becomes available, the Utilities expect that additional liability may be accrued, the amount of which is not presently determinable but may be material. The Utilities are permitted to recover or defer as regulatory assets (for subsequent recovery through rates) prudently incurred site investigation and remediation costs. Environmental remediation costs incurred related to Superfund Sites for the three and nine months ended September 30, 2017 and 2016 were as follows: For the Three Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Remediation costs incurred $4 $8 $3 $5 For the Nine Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Remediation costs incurred $18 $20 $13 $10 Insurance recoveries received by Con Edison or CECONY were immaterial for the three and nine months ended September 30, 2017 . Con Edison and CECONY received $1 million in insurance recoveries for the three and nine months ended September 30, 2016 . In 2016, Con Edison and CECONY estimated that for their manufactured gas plant sites (including CECONY’s Astoria site), the aggregate undiscounted potential liability for the investigation and remediation of coal tar and/or other environmental contaminants could range up to $2.8 billion and $2.6 billion , respectively. These estimates were based on the assumption that there is contamination at all sites, including those that have not yet been fully investigated and additional assumptions about the extent of the contamination and the type and extent of the remediation that may be required. Actual experience may be materially different. Asbestos Proceedings Suits have been brought in New York State and federal courts against the Utilities and many other defendants, wherein a large number of plaintiffs sought large amounts of compensatory and punitive damages for deaths and injuries allegedly caused by exposure to asbestos at various premises of the Utilities. The suits that have been resolved, which are many, have been resolved without any payment by the Utilities, or for amounts that were not, in the aggregate, material to them. The amounts specified in all the remaining thousands of suits total billions of dollars; however, the Utilities believe that these amounts are greatly exaggerated, based on the disposition of previous claims. At September 30, 2017 , Con Edison and CECONY have accrued their estimated aggregate undiscounted potential liabilities for these suits and additional suits that may be brought over the next 15 years as shown in the following table. These estimates were based upon a combination of modeling, historical data analysis and risk factor assessment. Courts have begun, and unless otherwise determined on appeal may continue, to apply different standards for determining liability in asbestos suits than the standard that applied historically. As a result, the Companies currently believe that there is a reasonable possibility of an exposure to loss in excess of the liability accrued for the suits. The Companies are unable to estimate the amount or range of such loss. In addition, certain current and former employees have claimed or are claiming workers’ compensation benefits based on alleged disability from exposure to asbestos. CECONY is permitted to defer as regulatory assets (for subsequent recovery through rates) costs incurred for its asbestos lawsuits and workers’ compensation claims. The accrued liability for asbestos suits and workers’ compensation proceedings (including those related to asbestos exposure) and the amounts deferred as regulatory assets for the Companies at September 30, 2017 and December 31, 2016 were as follows: Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Accrued liability – asbestos suits $8 $8 $7 $7 Regulatory assets – asbestos suits $8 $8 $7 $7 Accrued liability – workers’ compensation $87 $88 $83 $83 Regulatory assets – workers’ compensation $12 $13 $12 $13

Other Material Contingencies

Other Material Contingencies	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Other Material Contingencies	10 years Total (Millions of Dollars) Con Edison Transmission $643 $404 $— $1,047 Energy transactions 459 30 211 700 Renewable electric production projects 268 — 19 287 Other 128 — — 128 Total $1,498 $434 $230 $2,162 Con Edison Transmission — Con Edison has guaranteed payment by CET Electric of the contributions CET Electric agreed to make to New York Transco LLC (NY Transco). CET Electric acquired a 45.7 percent interest in NY Transco when it was formed in 2014. In May 2016, the transmission owners transferred certain projects to NY Transco, for which CET Electric made its required contributions. NY Transco has proposed other transmission projects in the New York Independent System Operator's competitive bidding process. These other projects are subject to certain authorizations from the NYSPSC, the FERC and, as applicable, other federal, state and local agencies. Guarantee amount shown is for the maximum possible required amount of CET Electric’s contributions for these other projects as calculated based on the assumptions that the projects are completed at 175 percent of their estimated costs and NY Transco does not use any debt financing for the projects. Guarantee term shown is assumed as the selection of the projects and resulting timing of the contributions is not certain. Also included within the table above is a guarantee for $25 million from Con Edison on behalf of CET Gas in relation to a proposed gas transmission project in West Virginia and Virginia. Energy Transactions — Con Edison guarantees payments on behalf of the Clean Energy Businesses in order to facilitate physical and financial transactions in electricity, gas, pipeline capacity, transportation, oil, renewable energy credits and energy services. To the extent that liabilities exist under the contracts subject to these guarantees, such liabilities are included in Con Edison’s consolidated balance sheet. Renewable Electric Production Projects — Con Edison, Con Edison Development, and Con Edison Solutions guarantee payments on behalf of their wholly-owned subsidiaries associated with their investment in, or development for others of, solar and wind energy facilities. Other — Other guarantees include $70 million in guarantees provided by Con Edison to Travelers Insurance Company for indemnity agreements for surety bonds in connection with operation of solar energy facilities and energy service projects of Con Edison Development and Con Edison Solutions, respectively. Other guarantees also includes Con Edison's guarantee (subject to a $53 million maximum amount) of certain obligations of Con Edison Solutions under the agreement pursuant to which it sold its retail electric supply business. In addition, Con Edison issued a guarantee estimated at $5 million to the Public Utility Commission of Texas covering obligations of Con Edison Solutions as a retail electric provider. As part of the sale agreement for the retail electric supply business discussed above, the purchaser has agreed to pay Con Edison Solutions for draws on the guarantee to the Public Utility Commission of Texas." id="sjs-B4">Other Material Contingencies Manhattan Explosion and Fire On March 12, 2014, two multi-use five-story tall buildings located on Park Avenue between 116 th and 117 th Streets in Manhattan were destroyed by an explosion and fire. CECONY had delivered gas to the buildings through service lines from a distribution main located below ground on Park Avenue. Eight people died and more than 50 people were injured. Additional buildings were also damaged. The National Transportation Safety Board (NTSB) investigated. The parties to the investigation included the company, the City of New York, the Pipeline and Hazardous Materials Safety Administration and the NYSPSC. In June 2015, the NTSB issued a final report concerning the incident, its probable cause and safety recommendations. The NTSB determined that the probable cause of the incident was (1) the failure of a defective fusion joint at a service tee (which joined a plastic service line to a plastic distribution main) installed by the company that allowed gas to leak from the distribution main and migrate into a building where it ignited and (2) a breach in a City sewer line that allowed groundwater and soil to flow into the sewer, resulting in a loss of support for the distribution main, which caused it to sag and overstressed the defective fusion joint. The NTSB also made safety recommendations, including recommendations to the company that addressed its procedures for the preparation and examination of plastic fusions, training of its staff on conditions for notifications to the City’s Fire Department and extension of its gas main isolation valve installation program. In February 2017, the NYSPSC approved a settlement agreement with the company related to the NYSPSC's investigations of the incident and the practices of qualifying persons to perform plastic fusions. Pursuant to the agreement, the company will not recover from customers $126 million of costs it incurred for gas emergency response activities in 2014, 2015 and 2016 in excess of the amounts reflected in its gas rate plan and will provide $27 million of future benefits to customers (for which it has accrued a regulatory liability, see Note B). Approximately eighty suits are pending against the company seeking generally unspecified damages and, in some cases, punitive damages, for wrongful death, personal injury, property damage and business interruption. The company has notified its insurers of the incident and believes that the policies in force at the time of the incident will cover the company’s costs, in excess of a required retention (the amount of which is not material), to satisfy any liability it may have for damages in connection with the incident. The company is unable to estimate the amount or range of its possible loss for damages related to the incident. At September 30, 2017 , the company had not accrued a liability for damages related to the incident. Other Contingencies See "Other Regulatory Matters" in Note B and “Uncertain Tax Positions” in Note I. Guarantees Con Edison and its subsidiaries enter into various agreements providing financial or performance assurance primarily to third parties on behalf of their subsidiaries. Maximum amounts guaranteed by Con Edison totaled $2,162 million and $2,370 million at September 30, 2017 and December 31, 2016 , respectively. A summary, by type and term, of Con Edison’s total guarantees at September 30, 2017 is as follows: Guarantee Type 0 – 3 years 4 – 10 years > 10 years Total (Millions of Dollars) Con Edison Transmission $643 $404 $— $1,047 Energy transactions 459 30 211 700 Renewable electric production projects 268 — 19 287 Other 128 — — 128 Total $1,498 $434 $230 $2,162 Con Edison Transmission — Con Edison has guaranteed payment by CET Electric of the contributions CET Electric agreed to make to New York Transco LLC (NY Transco). CET Electric acquired a 45.7 percent interest in NY Transco when it was formed in 2014. In May 2016, the transmission owners transferred certain projects to NY Transco, for which CET Electric made its required contributions. NY Transco has proposed other transmission projects in the New York Independent System Operator's competitive bidding process. These other projects are subject to certain authorizations from the NYSPSC, the FERC and, as applicable, other federal, state and local agencies. Guarantee amount shown is for the maximum possible required amount of CET Electric’s contributions for these other projects as calculated based on the assumptions that the projects are completed at 175 percent of their estimated costs and NY Transco does not use any debt financing for the projects. Guarantee term shown is assumed as the selection of the projects and resulting timing of the contributions is not certain. Also included within the table above is a guarantee for $25 million from Con Edison on behalf of CET Gas in relation to a proposed gas transmission project in West Virginia and Virginia. Energy Transactions — Con Edison guarantees payments on behalf of the Clean Energy Businesses in order to facilitate physical and financial transactions in electricity, gas, pipeline capacity, transportation, oil, renewable energy credits and energy services. To the extent that liabilities exist under the contracts subject to these guarantees, such liabilities are included in Con Edison’s consolidated balance sheet. Renewable Electric Production Projects — Con Edison, Con Edison Development, and Con Edison Solutions guarantee payments on behalf of their wholly-owned subsidiaries associated with their investment in, or development for others of, solar and wind energy facilities. Other — Other guarantees include $70 million in guarantees provided by Con Edison to Travelers Insurance Company for indemnity agreements for surety bonds in connection with operation of solar energy facilities and energy service projects of Con Edison Development and Con Edison Solutions, respectively. Other guarantees also includes Con Edison's guarantee (subject to a $53 million maximum amount) of certain obligations of Con Edison Solutions under the agreement pursuant to which it sold its retail electric supply business. In addition, Con Edison issued a guarantee estimated at $5 million to the Public Utility Commission of Texas covering obligations of Con Edison Solutions as a retail electric provider. As part of the sale agreement for the retail electric supply business discussed above, the purchaser has agreed to pay Con Edison Solutions for draws on the guarantee to the Public Utility Commission of Texas.

Income Tax

Income Tax	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Tax	Income Tax Con Edison’s income tax expense decreased to $270 million for the three months ended September 30, 2017 from $314 million for the three months ended September 30, 2016 . Con Edison's effective tax rate for the three months ended September 30, 2017 and 2016 was 37 percent and 39 percent , respectively. The decrease in Con Edison's effective tax rate is primarily due to lower state income taxes, offset in part by a decrease in tax benefits for plant-related flow through items. CECONY’s income tax expense increased to $242 million for the three months ended September 30, 2017 from $226 million for the three months ended September 30, 2016 . CECONY's effective tax rate for the three months ended September 30, 2017 and 2016 was 38 percent and 37 percent , respectively. The increase in CECONY's effective tax rate is primarily due to a decrease in tax benefits for plant-related flow through items and lower research and development credits, offset in part by lower state income taxes. Con Edison’s income tax expense decreased to $599 million for the nine months ended September 30, 2017 from $602 million for the nine months ended September 30, 2016 . Con Edison's effective tax rate for the nine months ended September 30, 2017 and 2016 was 37 percent . The effective tax rate remained unchanged as lower state income taxes were offset by a decrease in tax benefits for plant-related flow through items. CECONY’s income tax expense increased to $551 million for the nine months ended September 30, 2017 from $491 million for the nine months ended September 30, 2016 . CECONY's effective tax rate for the nine months ended September 30, 2017 and 2016 was 38 percent and 36 percent , respectively. The increase in CECONY's effective tax rate is primarily due to a decrease in tax benefits for plant-related flow through items and lower research and development tax credits, offset in part by lower state income taxes. Con Edison anticipates a federal consolidated net operating loss for 2017, primarily due to bonus depreciation. Con Edison expects to carryback a portion of its 2017 net operating loss to recover $19 million of income tax. The remaining 2017 net operating loss, as well as general business tax credits generated in 2017, will be carried forward to future tax years. A deferred tax asset for these tax attribute carryforwards was recorded, and no valuation allowance has been provided, as it is more likely than not that the deferred tax asset will be realized. Uncertain Tax Positions At September 30, 2017 , the estimated liability for uncertain tax positions for Con Edison was $41 million ( $21 million for CECONY). Con Edison reasonably expects to resolve approximately $35 million ( $24 million , net of federal taxes) of its uncertain tax positions within the next twelve months, including $21 million ( $15 million , net of federal taxes), which, if recognized, would reduce Con Edison’s effective tax rate. The amount related to CECONY is approximately $18 million ( $13 million , net of federal taxes), including $4 million , which, if recognized, would reduce CECONY’s effective tax rate. The total amount of unrecognized tax benefits, if recognized, that would reduce Con Edison’s effective tax rate is $25 million ( $18 million , net of federal taxes). The Companies recognize interest on liabilities for uncertain tax positions in interest expense and would recognize penalties, if any, in operating expenses in the Companies’ consolidated income statements. In the three and nine months ended September 30, 2017 , the Companies recognized an immaterial amount of interest expense and no penalties for uncertain tax positions in their consolidated income statements. At September 30, 2017 and December 31, 2016 , the Companies recognized an immaterial amount of accrued interest on their consolidated balance sheets.

Financial Information by Busine

Financial Information by Business Segment	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Financial Information by Business Segment	Financial Information by Business Segment Con Edison’s principal business segments are CECONY’s regulated utility activities, O&R’s regulated utility activities, the Clean Energy Businesses and Con Edison Transmission. CECONY’s principal business segments are its regulated electric, gas and steam utility activities. The financial data for the business segments for the three and nine months ended September 30, 2017 and 2016 were as follows: For the Three Months Ended September 30, Operating revenues Inter-segment revenues Depreciation and amortization Operating income/(loss) (Millions of Dollars) 2017 2016 2017 2016 2017 2016 2017 2016 CECONY Electric $2,469 $2,557 $4 $5 $232 $217 $855 $841 Gas 268 208 2 1 47 41 (12) (28) Steam 62 63 19 22 21 20 (43) (47) Consolidation adjustments — — (25) (28) — — — — Total CECONY $2,799 $2,828 $— $— $300 $278 $800 $766 O&R Electric $206 $213 $— $— $13 $12 $56 $55 Gas 28 27 — — 5 5 (11) (7) Total O&R $234 $240 $— $— $18 $17 $45 $48 Clean Energy Businesses $177 $350 $— $(2) $19 $11 $29 $125 Con Edison Transmission 1 — — — — — (2) (1) Other (a) — (1) — 2 — (1) 1 2 Total Con Edison $3,211 $3,417 $— $— $337 $305 $873 $940 For the Nine Months Ended September 30, Operating revenues Inter-segment revenues Depreciation and amortization Operating income/(loss) (Millions of Dollars) 2017 2016 2017 2016 2017 2016 2017 2016 CECONY Electric $6,079 $6,222 $12 $13 $690 $645 $1,477 $1,487 Gas 1,421 1,113 5 4 137 118 362 273 Steam 448 406 55 65 64 62 52 39 Consolidation adjustments — — (72) (82) — — — — Total CECONY $7,948 $7,741 $— $— $891 $825 $1,891 $1,799 O&R Electric $495 $497 $— $— $38 $37 $83 $86 Gas 172 133 — — 15 13 33 28 Total O&R $667 $630 $— $— $53 $50 $116 $114 Clean Energy Businesses $460 $998 $— $7 $54 $30 $63 $184 Con Edison Transmission 1 — — — — — (6) (1) Other (a) (4) (1) — (7) — — 2 1 Total Con Edison $9,072 $9,368 $— $— $998 $905 $2,066 $2,097 (a) Parent company and consolidation adjustments. Other does not represent a business segment.

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	9 Months Ended
	Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities Con Edison’s subsidiaries hedge market price fluctuations associated with physical purchases and sales of electricity, natural gas, steam and, to a lesser extent, refined fuels by using derivative instruments including futures, forwards, basis swaps, options, transmission congestion contracts and financial transmission rights contracts. Derivatives are recognized on the consolidated balance sheet at fair value (see Note L), unless an exception is available under the accounting rules for derivatives and hedging. Qualifying derivative contracts that have been designated as normal purchases or normal sales contracts are not reported at fair value under the accounting rules. The fair values of the Companies’ commodity derivatives including the offsetting of assets and liabilities on the consolidated balance sheet at September 30, 2017 and December 31, 2016 were: (Millions of Dollars) 2017 2016 Balance Sheet Location Gross Amounts of Recognized Assets/(Liabilities) Gross Amounts Offset Net Amounts of Assets/ (Liabilities) (a) Gross Amounts of Recognized Assets/(Liabilities) Gross Amounts Offset Net Amounts of Assets/ (Liabilities) (a) Con Edison Fair value of derivative assets Current $77 $(67) $10 (b) $81 $(64) $17 (b) Noncurrent 64 (61) 3 49 (43) 6 Total fair value of derivative assets $141 $(128) $13 $130 $(107) $23 Fair value of derivative liabilities Current $(141) $71 $(70) $(138) $61 $(77) Noncurrent (143) 60 (83) (91) 52 (39) (c) Total fair value of derivative liabilities $(284) $131 $(153) $(229) $113 $(116) Net fair value derivative assets/(liabilities) $(143) $3 $(140) (b) $(99) $6 $(93) (b) (c) CECONY Fair value of derivative assets Current $55 $(53) $2 (b) $52 $(45) $7 (b) Noncurrent 57 (55) 2 41 (35) 6 Total fair value of derivative assets $112 $(108) $4 $93 $(80) $13 Fair value of derivative liabilities Current $(116) $57 $(59) $(111) $45 $(66) Noncurrent (127) 54 (73) (77) 44 (33) Total fair value of derivative liabilities $(243) $111 $(132) $(188) $89 $(99) Net fair value derivative assets/(liabilities) $(131) $3 $(128) (b) $(95) $9 $(86) (b) (a) Derivative instruments and collateral were offset on the consolidated balance sheet as applicable under the accounting rules. The Companies enter into master agreements for their commodity derivatives. These agreements typically provide offset in the event of contract termination. In such case, generally the non-defaulting party’s payable will be offset by the defaulting party’s payable. The non-defaulting party will customarily notify the defaulting party within a specific time period and come to an agreement on the early termination amount. (b) At September 30, 2017 and December 31, 2016 , margin deposits for Con Edison ( $5 million and $7 million , respectively) and CECONY ( $5 million and $7 million , respectively) were classified as derivative assets on the consolidated balance sheet, but not included in the table. Margin is collateral, typically cash, that the holder of a derivative instrument is required to deposit in order to transact on an exchange and to cover its potential losses with its broker or the exchange. (c) Does not include $(1) million for interest rate swap. The Utilities generally recover their prudently incurred fuel, purchased power and gas costs, including hedging gains and losses, in accordance with rate provisions approved by the applicable state utility regulators. In accordance with the accounting rules for regulated operations, the Utilities record a regulatory asset or liability to defer recognition of unrealized gains and losses on their electric and gas derivatives. As gains and losses are realized in future periods, they will be recognized as purchased power, gas and fuel costs in the Companies’ consolidated income statements. The Clean Energy Businesses record realized and unrealized gains and losses on their derivative contracts in purchased power, gas purchased for resale and non-utility revenue in the reporting period in which they occur. Management believes that these derivative instruments represent economic hedges that mitigate exposure to fluctuations in commodity prices. The following table presents the realized and unrealized gains or losses on commodity derivatives that have been deferred or recognized in earnings for the three and nine months ended September 30, 2017 and 2016 : For the Three Months Ended September 30, Con Edison CECONY (Millions of Dollars) Balance Sheet Location 2017 2016 2017 2016 Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations: Current Deferred derivative gains $(4) $(1) $(3) $(3) Noncurrent Deferred derivative gains 1 (2) 1 — Total deferred gains/(losses) $(3) $(3) $(2) $(3) Current Deferred derivative losses $(11) $(19) $(9) $(18) Current Recoverable energy costs (40) (39) (38) (35) Noncurrent Deferred derivative losses (12) (17) (8) (14) Total deferred gains/(losses) $(63) $(75) $(55) $(67) Net deferred gains/(losses) $(66) $(78) $(57) $(70) Income Statement Location Pre-tax gains/(losses) recognized in income Purchased power expense $— $(37) (b) $— $— Gas purchased for resale (47) (38) — — Non-utility revenue 5 (a) (2) (b) — — Total pre-tax gains/(losses) recognized in income $(42) $(77) $— $— (a) For the three months ended September 30, 2017 , Con Edison recorded an unrealized pre-tax gain in non-utility operating revenue ( $6 million ). (b) For the three months ended September 30, 2016 , Con Edison recorded unrealized pre-tax losses in non-utility operating revenue ( $2 million ) and purchased power expense ( $23 million ). For the Nine Months Ended September 30, Con Edison CECONY (Millions of Dollars) Balance Sheet Location 2017 2016 2017 2016 Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations: Current Deferred derivative gains $(26) $6 $(22) $2 Noncurrent Deferred derivative gains (2) (1) (2) (1) Total deferred gains/(losses) $(28) $5 $(24) $1 Current Deferred derivative losses $10 $19 $11 $16 Current Recoverable energy costs (125) (163) (116) (148) Noncurrent Deferred derivative losses (40) (5) (36) (3) Total deferred gains/(losses) $(155) $(149) $(141) $(135) Net deferred gains/(losses) $(183) $(144) $(165) $(134) Income Statement Location Pre-tax gains/(losses) recognized in income Purchased power expense $— $(106) (b) $— $— Gas purchased for resale (161) (72) — — Non-utility revenue 11 (a) 15 (b) — — Total pre-tax gains/(losses) recognized in income $(150) $(163) $— $— (a) For the nine months ended September 30, 2017 , Con Edison recorded an unrealized pre-tax gain in non-utility operating revenue ( $2 million ). (b) For the nine months ended September 30, 2016 , Con Edison recorded unrealized pre-tax gains and losses in non-utility operating revenue ( $3 million loss) and purchased power expense ( $11 million gain). The following table presents the hedged volume of Con Edison’s and CECONY’s derivative transactions at September 30, 2017 : Electric Energy (MWh) (a)(b) Capacity (MW) (a) Natural Gas (Dt) (a)(b) Refined Fuels (gallons) Con Edison 32,596,372 6,790 166,913,644 672,000 CECONY 30,492,575 3,000 158,500,000 672,000 (a) Volumes are reported net of long and short positions, except natural gas collars where the volumes of long positions are reported. (b) Excludes electric congestion and gas basis swap contracts, which are associated with electric and gas contracts and hedged volumes. The Companies are exposed to credit risk related to transactions entered into primarily for the various energy supply and hedging activities by the Utilities and the Clean Energy Businesses. Credit risk relates to the loss that may result from a counterparty’s nonperformance. The Companies use credit policies to manage this risk, including an established credit approval process, monitoring of counterparty limits, netting provisions within agreements, collateral or prepayment arrangements, credit insurance and credit default swaps. The Companies measure credit risk exposure as the replacement cost for open energy commodity and derivative positions plus amounts owed from counterparties for settled transactions. The replacement cost of open positions represents unrealized gains, net of any unrealized losses where the Companies have a legally enforceable right to offset. At September 30, 2017 , Con Edison and CECONY had $80 million and $8 million of credit exposure in connection with energy supply and hedging activities, net of collateral, respectively. Con Edison’s net credit exposure consisted of $23 million with investment-grade counterparties, $23 million with non-investment grade/non-rated counterparties, $19 million with independent system operators and $15 million with commodity exchange brokers. CECONY’s net credit exposure consisted of $7 million with commodity exchange brokers and $1 million with investment-grade counterparties. The collateral requirements associated with, and settlement of, derivative transactions are included in net cash flows from operating activities in the Companies’ consolidated statement of cash flows. Most derivative instrument contracts contain provisions that may require a party to provide collateral on its derivative instruments that are in a net liability position. The amount of collateral to be provided will depend on the fair value of the derivative instruments and the party’s credit ratings. The following table presents the aggregate fair value of the Companies’ derivative instruments with credit-risk-related contingent features that are in a net liability position, the collateral posted for such positions and the additional collateral that would have been required to be posted had the lowest applicable credit rating been reduced one level and to below investment grade at September 30, 2017 : (Millions of Dollars) Con Edison (a) CECONY (a) Aggregate fair value – net liabilities $148 $131 Collateral posted 61 56 Additional collateral (b) (downgrade one level from current ratings) 23 22 Additional collateral (b) (downgrade to below investment grade from current ratings) 101 (c) 88 (c) (a) Non-derivative transactions for the purchase and sale of electricity and gas and qualifying derivative instruments, which have been designated as normal purchases or normal sales, are excluded from the table. These transactions primarily include purchases of electricity from independent system operators. In the event the Utilities and the Clean Energy Businesses were no longer extended unsecured credit for such purchases, the Companies would be required to post additional collateral of $11 million at September 30, 2017 . For certain other such non-derivative transactions, the Companies could be required to post collateral under certain circumstances, including in the event counterparties had reasonable grounds for insecurity. (b) The Companies measure the collateral requirements by taking into consideration the fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position plus amounts owed to counterparties for settled transactions and amounts required by counterparties for minimum financial security. The fair value amounts represent unrealized losses, net of any unrealized gains where the Companies have a legally enforceable right to offset. (c) Derivative instruments that are net assets have been excluded from the table. At September 30, 2017 , if Con Edison had been downgraded to below investment grade, it would have been required to post additional collateral for such derivative instruments of $13 million . Interest Rate Swap In December 2016, the Clean Energy Businesses acquired Coram Wind project which holds an interest rate swap that terminates in June 2024, pursuant to which it pays a fixed-rate of 2.0855 percent and receives a LIBOR-based variable rate. The fair value of this interest rate swap was immaterial as of September 30, 2017 and a liability of $1 million as of December 31, 2016 on Con Edison’s consolidated balance sheet.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The accounting rules for fair value measurements and disclosures define fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date in a principal or most advantageous market. Fair value is a market-based measurement that is determined based on inputs, which refer broadly to assumptions that market participants use in pricing assets or liabilities. These inputs can be readily observable, market corroborated, or generally unobservable firm inputs. The Companies often make certain assumptions that market participants would use in pricing the asset or liability, including assumptions about risk, and the risks inherent in the inputs to valuation techniques. The Companies use valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. The accounting rules for fair value measurements and disclosures established a fair value hierarchy, which prioritizes the inputs to valuation techniques used to measure fair value in three broad levels. The rules require that assets and liabilities be classified in their entirety based on the level of input that is significant to the fair value measurement. Assessing the significance of a particular input may require judgment considering factors specific to the asset or liability, and may affect the valuation of the asset or liability and their placement within the fair value hierarchy. The Companies classify fair value balances based on the fair value hierarchy defined by the accounting rules for fair value measurements and disclosures as follows: • Level 1 – Consists of assets or liabilities whose value is based on unadjusted quoted prices in active markets at the measurement date. An active market is one in which transactions for assets or liabilities occur with sufficient frequency and volume to provide pricing information on an ongoing basis. This category includes contracts traded on active exchange markets valued using unadjusted prices quoted directly from the exchange. • Level 2 – Consists of assets or liabilities valued using industry standard models and based on prices, other than quoted prices within Level 1, that are either directly or indirectly observable as of the measurement date. The industry standard models consider observable assumptions including time value, volatility factors and current market and contractual prices for the underlying commodities, in addition to other economic measures. This category includes contracts traded on active exchanges or in over-the-counter markets priced with industry standard models. • Level 3 – Consists of assets or liabilities whose fair value is estimated based on internally developed models or methodologies using inputs that are generally less readily observable and supported by little, if any, market activity at the measurement date. Unobservable inputs are developed based on the best available information and subject to cost benefit constraints. This category includes contracts priced using models that are internally developed and contracts placed in illiquid markets. It also includes contracts that expire after the period of time for which quoted prices are available and internal models are used to determine a significant portion of the value. Assets and liabilities measured at fair value on a recurring basis as of September 30, 2017 and December 31, 2016 are summarized below. 2017 2016 (Millions of Dollars) Level 1 Level 2 Level 3 Netting Adjustment (e) Total Level 1 Level 2 Level 3 Netting Adjustment (e) Total Con Edison Derivative assets: Commodity (a)(b)(c) $6 $28 $2 $(18) $18 $14 $33 $7 $(24) $30 Other (a)(b)(d) 271 118 — — 389 222 111 — — 333 Total assets $277 $146 $2 $(18) $407 $236 $144 $7 $(24) $363 Derivative liabilities: Commodity (a)(b)(c) $2 $155 $22 $(26) $153 $4 $144 $6 $(38) $116 Interest Rate Swap (a)(b)(c) — — — — — — 1 — — 1 Total liabilities $2 $155 $22 $(26) $153 $4 $145 $6 $(38) $117 CECONY Derivative assets: Commodity (a)(b)(c) $5 $12 $1 $(9) $9 $10 $19 $1 $(10) $20 Other (a)(b)(d) 248 113 — — 361 200 106 — — 306 Total assets $253 $125 $1 $(9) $370 $210 $125 $1 $(10) $326 Derivative liabilities: Commodity (a)(b)(c) $1 $133 $15 $(17) $132 $1 $124 $— $(26) $99 (a) The Companies’ policy is to review the fair value hierarchy and recognize transfers into and transfers out of the levels at the end of each reporting period. There were no transfers between levels 1, 2 and 3 for the nine months ended September 30, 2017 and for the year ended December 31, 2016 . (b) Level 2 assets and liabilities include investments held in the deferred compensation plan and/or non-qualified retirement plans, exchange-traded contracts where there is insufficient market liquidity to warrant inclusion in Level 1, certain over-the-counter derivative instruments for electricity, refined products and natural gas. Derivative instruments classified as Level 2 are valued using industry standard models that incorporate corroborated observable inputs; such as pricing services or prices from similar instruments that trade in liquid markets, time value and volatility factors. (c) The accounting rules for fair value measurements and disclosures require consideration of the impact of nonperformance risk (including credit risk) from a market participant perspective in the measurement of the fair value of assets and liabilities. At September 30, 2017 and December 31, 2016 , the Companies determined that nonperformance risk would have no material impact on their financial position or results of operations. (d) Other assets are comprised of assets such as life insurance contracts within the deferred compensation plan and non-qualified retirement plans. (e) Amounts represent the impact of legally-enforceable master netting agreements that allow the Companies to net gain and loss positions and cash collateral held or placed with the same counterparties. The employees in the Companies’ risk management group develop and maintain the Companies’ valuation policies and procedures for, and verify pricing and fair value valuation of, commodity derivatives. Under the Companies’ policies and procedures, multiple independent sources of information are obtained for forward price curves used to value commodity derivatives. Fair value and changes in fair value of commodity derivatives are reported on a monthly basis to the Companies’ risk committees, comprised of officers and employees of the Companies that oversee energy hedging at the Utilities and the Clean Energy Businesses. The risk management group reports to the Companies’ Vice President and Treasurer. Fair Value of Level 3 at September 30, 2017 Valuation Techniques Unobservable Inputs Range (Millions of Dollars) Con Edison – Commodity Electricity $(21) Discounted Cash Flow Forward energy prices (a) $19.00-$76.25 per MWh Discounted Cash Flow Forward capacity prices (a) $1.26-$9.47 per kW-month Transmission Congestion Contracts/Financial Transmission Rights 1 Discounted Cash Flow Discount to adjust auction prices for inter-zonal forward price curves (b) 50.0% Inter-zonal forward price curves adjusted for historical zonal losses (b) $0.50-$6.75 per MWh Total Con Edison—Commodity $(20) CECONY – Commodity Electricity $(15) Discounted Cash Flow Forward energy prices (a) $20.50-$76.25 per MWh Transmission Congestion Contracts 1 Discounted Cash Flow Discount to adjust auction prices for inter-zonal forward price curves (b) 50.0% Total CECONY—Commodity $(14) (a) Generally, increases/(decreases) in this input in isolation would result in a higher/(lower) fair value measurement. (b) Generally, increases/(decreases) in this input in isolation would result in a lower/(higher) fair value measurement. The table listed below provides a reconciliation of the beginning and ending net balances for assets and liabilities measured at fair value as of September 30, 2017 and 2016 and classified as Level 3 in the fair value hierarchy: For the Three Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Beginning balance as of July 1, $(10) $5 $(6) $2 Included in earnings 7 (4) 1 — Included in regulatory assets and liabilities (13) (5) (8) (3) Sales — 4 — — Settlements (4) 1 (1) 1 Ending balance as of September 30, $(20) $1 $(14) $— For the Nine Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Beginning balance as of January 1, $1 $6 $1 $8 Included in earnings 8 (1) 1 (1) Included in regulatory assets and liabilities (21) (11) (14) (6) Purchases 1 2 1 1 Sales — 4 — — Settlements (9) 1 (3) (2) Ending balance as of September 30, $(20) $1 $(14) $— For the Utilities, realized gains and losses on Level 3 commodity derivative assets and liabilities are reported as part of purchased power, gas and fuel costs. The Utilities generally recover these costs in accordance with rate provisions approved by the applicable state public utilities regulators. Unrealized gains and losses for commodity derivatives are generally deferred on the consolidated balance sheet in accordance with the accounting rules for regulated operations. For the Clean Energy Businesses, realized and unrealized gains and losses on Level 3 commodity derivative assets and liabilities are reported in non-utility revenues (immaterial for both periods) and purchased power costs ( $4 million gain and $5 million loss ) on the consolidated income statement for the three months ended September 30, 2017 and 2016 , respectively. Realized and unrealized gains and losses on Level 3 commodity derivative assets and liabilities are reported in non-utility revenues (immaterial for both periods) and purchased power costs ( $3 million gain and $6 million loss ) on the consolidated income statement for the nine months ended September 30, 2017 and 2016 , respectively. The change in fair value relating to Level 3 commodity derivative assets and liabilities held at September 30, 2017 and 2016 is included in non-utility revenues ( immaterial for both periods) and purchased power costs ( $4 million gain and $4 million loss ) on the consolidated income statement for the three months ended September 30, 2017 and 2016 , respectively. For the nine months ended September 30, 2017 and 2016 , the change in fair value relating to Level 3 commodity derivative assets and liabilities is included in non-utility revenues (immaterial for both periods) and purchased power costs ( $2 million gain and $2 million loss ) on the consolidated income statement, respectively.

Variable Interest Entities

Variable Interest Entities	9 Months Ended
	Sep. 30, 2017
Equity Method Investments and Joint Ventures [Abstract]
Variable Interest Entities	Variable Interest Entities Con Edison enters into arrangements including leases, partnerships and electricity purchase agreements, with various entities. As a result of these arrangements, Con Edison retains or may retain a variable interest in these entities. CECONY has an ongoing long-term electricity purchase agreement with Brooklyn Navy Yard Cogeneration Partners, LP, a potential variable interest entity (VIE). In April 2017, CECONY's long-term electricity purchase agreement with Cogen Technologies Linden Venture, LP, another potential VIE, expired. In 2016 , requests were made of these counterparties for information necessary to determine whether the entity was a VIE and whether CECONY is the primary beneficiary; however, the information was not made available. The payments for these contracts constitute CECONY’s maximum exposure to loss with respect to the potential VIEs. The following table summarizes the VIEs in which Con Edison Development has entered into as of September 30, 2017 : Project Name (a) Generating Capacity (b) (MW AC) Power Purchase Agreement Term (in Years) Year of Initial Investment Location Maximum Exposure to Loss ( Millions of Dollars ) (c) Copper Mountain Solar 3 128 20 2014 Nevada $175 Mesquite Solar 1 83 20 2013 Arizona 102 Copper Mountain Solar 2 75 25 2013 Nevada 83 California Solar 55 25 2012 California 64 Broken Bow II 38 25 2014 Nebraska 44 Texas Solar 4 32 25 2014 Texas 47 (a) With the exception of Texas Solar 4, Con Edison’s ownership interest is 50 percent and these projects are accounted for using the equity method of accounting. With the exception of Texas Solar 4, Con Edison is not the primary beneficiary since the power to direct the activities that most significantly impact the economics of the entities are shared equally between Con Edison Development and third parties. Con Edison’s ownership interest in Texas Solar 4 is 80 percent and is consolidated in the financial statements. Con Edison is the primary beneficiary since the power to direct the activities that most significantly impact the economics of Texas Solar 4 is held by Con Edison Development. (b) Represents Con Edison Development’s ownership interest in the project. (c) For investments accounted for under the equity method, maximum exposure is equal to the carrying value of the investment on the consolidated balance sheet. For consolidated investments, such as Texas Solar 4, maximum exposure is equal to the net assets of the project on the consolidated balance sheet less any applicable noncontrolling interest ( $7 million for Texas Solar 4). Con Edison did not provide any financial or other support during the three and nine months ended September 30, 2017 that was not previously contractually required.

New Financial Accounting Standa

New Financial Accounting Standards	9 Months Ended
	Sep. 30, 2017
Accounting Changes and Error Corrections [Abstract]
New Financial Accounting Standards	New Financial Accounting Standards In May 2014, the Financial Accounting Standards Board (FASB) and the International Accounting Standards Board jointly issued a revenue recognition standard that will supersede the revenue recognition requirements within Accounting Standards Codification Topic 605, “Revenue Recognition,” and most industry-specific guidance under the Codification through Accounting Standards Update (ASU) No. 2014-09, “Revenue from Contracts with Customers (Topic 606).” The purpose of the new guidance is to create a consistent framework for revenue recognition. The guidance clarifies how to measure and recognize revenue arising from customer contracts to depict the transfer of goods or services in an amount that reflects the consideration the entity expects to receive. Amendments were issued subsequently to clarify key areas including principal/agent considerations, performance obligations, licensing, sales taxes, noncash consideration, and contracts. The new standard is effective for reporting periods beginning after December 15, 2017. Early adoption is permitted for reporting periods beginning after December 15, 2016, however, the Companies plan to adopt the new standard for reporting periods beginning after December 15, 2017. Under the new standard, companies may use either of the following transition methods: (i) a full retrospective approach reflecting the application of the standard in each prior reporting period with the option to elect certain practical expedients, or (ii) a modified retrospective approach with the cumulative effect of initially adopting ASU 2014-09 recognized at the date of adoption (which includes additional footnote disclosures). The Companies anticipate using the modified retrospective approach. The Companies have completed their analyses of the impact of the new standard on the majority of their various revenue streams. The majority of the Companies’ sales are derived from tariffs to provide electric, gas, and steam service to customers. For such tariffs, the Companies expect that the revenue from contracts with customers under ASU 2014-09 will be equivalent to revenue from electricity, gas, or steam supplied in that period which is consistent with current practice. Consequently, the Companies do not anticipate that the new standard will materially impact the amount and/or timing of such revenues. Con Edison has also completed its evaluation for the majority of the revenue at the Clean Energy Businesses, including revenue from the sale of energy-related products and services to retail customers, revenue from operating renewable and energy infrastructure projects, and revenue from the sale of renewable energy credits. For such revenues, Con Edison expects that the revenue from contracts with customers under ASU 2014-09 will not be materially different from revenue recorded consistent with current practice. Consequently, Con Edison does not anticipate that the new standard will materially impact the amount and/or timing of such revenues. The Companies continue to review the potential impacts of the remaining revenue at the Utilities and the Clean Energy Businesses on the Companies' financial position, results of operations and liquidity as well as the additional disclosures and related controls required under the new standard, and anticipate completing such reviews during the fourth quarter of 2017. In February 2016, the FASB issued amendments on financial reporting of leasing transactions through ASU No. 2016-02, “Leases (Topic 842)." The amendments require lessees to recognize assets and liabilities on the balance sheet and disclose key information about leasing arrangements. Lessees will need to recognize a right-of-use asset and a lease liability for virtually all of their leases (other than leases that meet the definition of a short-term lease). Lessor accounting is similar to the current model, but updated to align with certain changes to the lessee model. For income statement purposes, the pattern of expense recognition will be dependent on whether transactions are designated as operating leases or finance leases. The amendments are effective for reporting periods beginning after December 15, 2018. Early adoption is permitted. The amendments must be adopted using a modified retrospective transition and provide for certain practical expedients. Based on the existing portfolio of leases at implementation, for leases currently classified as operating leases, the Companies expect to recognize on the statements of financial position right-of-use assets and lease liabilities. The Companies are in the process of evaluating the potential impact of the new guidance on the Companies’ results of operations and liquidity. In January 2017, the FASB issued amendments to the guidance for Business Combinations through ASU 2017-01, “Business Combinations (Topic 805): Clarifying the Definition of a Business.” The amendments in this update clarify the definition of a business and provide guidance on evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. For public entities, the amendments are effective for reporting periods beginning after December 15, 2017. Early adoption is permitted. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity. In January 2017, the FASB issued amendments to the guidance for the subsequent measurement of goodwill through ASU 2017-04, “Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” The amendments in this update simplify goodwill impairment testing by eliminating Step 2 of the goodwill impairment test wherein an entity has to compute the implied fair value of goodwill by performing procedures to determine the fair value of its assets and liabilities. Under the new guidance, an entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value up to the total amount of goodwill allocated to that reporting unit. For public entities, the amendments are effective for reporting periods beginning after December 15, 2019. Early adoption is permitted. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity. In February 2017, the FASB issued amendments to the guidance for other income through ASU 2017-05, “Other Income-Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets.” The amendments in this update clarify the scope of assets within Subtopic 610-20 and add guidance for partial sales of nonfinancial assets. The amendments are effective upon the adoption of ASU 2014-09, and therefore will be effective for reporting periods beginning after December 15, 2017. The Company is in the process of evaluating the potential impact of the new guidance on the Company’s financial position, results of operations and liquidity. In March 2017, the FASB issued amendments to the guidance for retirement benefits through ASU 2017-07, “Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.” The amendments in this update modify the presentation of net benefit cost, where the service component must be disaggregated from the other components of net benefit cost and be presented in the same line item as current employee compensation costs. The remaining components of the net benefit cost should be presented outside of income from operations. Additionally, the update allows only the service cost component to be eligible for capitalization. For public entities, the amendments are effective for reporting periods beginning after December 15, 2017. Early adoption is permitted. The Companies are in the process of evaluating the potential impact of the new guidance on the Companies’ financial position, results of operations and liquidity. In March 2017, the FASB issued amendments to the guidance for debt securities through ASU 2017-08, “Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities.” The amendments in this update shorten the amortization period for certain callable debt securities held at a premium. The amendments do not require an accounting change for securities held at a discount; the discount continues to be amortized to maturity. For public entities, the amendments are effective for reporting periods beginning after December 15, 2018. Early adoption is permitted. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity. In May 2017, the FASB issued amendments to the guidance for stock compensation through ASU 2017-09, “Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting.” The amendments in this update specify that changes to value, vesting conditions, or classification of an existing share-based payment award require application of modification accounting in Topic 718. For public entities, the amendments are effective for reporting periods beginning after December 15, 2017. Early adoption is permitted. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity. In August 2017, the FASB issued amendments to the guidance for derivatives and hedging through ASU 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities.” The amendments in this update provide greater clarification on hedge accounting for risk components, presentation and disclosure of hedging instruments, and overall targeted improvements to simplify hedge accounting. For public entities, the amendments are effective for reporting periods beginning after December 15, 2018 and interim periods within those fiscal years. Early adoption is permitted. The Companies are in the process of evaluating the potential impact of the new guidance on the Companies’ financial position, results of operations and liquidity.

Dispositions

Dispositions	9 Months Ended
	Sep. 30, 2017
Discontinued Operations and Disposal Groups [Abstract]
Dispositions	Dispositions Upton 2 In May 2017, Con Edison Development sold Upton 2, a development stage solar electric production project, for $11 million to Vistra Asset Co. and recorded a $1 million gain on sale ( $0.7 million , net of taxes). In addition, Con Edison Development agreed to perform the engineering, procurement and construction for the 180 MW (AC) project, which is expected to be substantially completed in 2018.

New Financial Accounting Stan24

New Financial Accounting Standards (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Changes and Error Corrections [Abstract]
New Financial Accounting Standards	New Financial Accounting Standards In May 2014, the Financial Accounting Standards Board (FASB) and the International Accounting Standards Board jointly issued a revenue recognition standard that will supersede the revenue recognition requirements within Accounting Standards Codification Topic 605, “Revenue Recognition,” and most industry-specific guidance under the Codification through Accounting Standards Update (ASU) No. 2014-09, “Revenue from Contracts with Customers (Topic 606).” The purpose of the new guidance is to create a consistent framework for revenue recognition. The guidance clarifies how to measure and recognize revenue arising from customer contracts to depict the transfer of goods or services in an amount that reflects the consideration the entity expects to receive. Amendments were issued subsequently to clarify key areas including principal/agent considerations, performance obligations, licensing, sales taxes, noncash consideration, and contracts. The new standard is effective for reporting periods beginning after December 15, 2017. Early adoption is permitted for reporting periods beginning after December 15, 2016, however, the Companies plan to adopt the new standard for reporting periods beginning after December 15, 2017. Under the new standard, companies may use either of the following transition methods: (i) a full retrospective approach reflecting the application of the standard in each prior reporting period with the option to elect certain practical expedients, or (ii) a modified retrospective approach with the cumulative effect of initially adopting ASU 2014-09 recognized at the date of adoption (which includes additional footnote disclosures). The Companies anticipate using the modified retrospective approach. The Companies have completed their analyses of the impact of the new standard on the majority of their various revenue streams. The majority of the Companies’ sales are derived from tariffs to provide electric, gas, and steam service to customers. For such tariffs, the Companies expect that the revenue from contracts with customers under ASU 2014-09 will be equivalent to revenue from electricity, gas, or steam supplied in that period which is consistent with current practice. Consequently, the Companies do not anticipate that the new standard will materially impact the amount and/or timing of such revenues. Con Edison has also completed its evaluation for the majority of the revenue at the Clean Energy Businesses, including revenue from the sale of energy-related products and services to retail customers, revenue from operating renewable and energy infrastructure projects, and revenue from the sale of renewable energy credits. For such revenues, Con Edison expects that the revenue from contracts with customers under ASU 2014-09 will not be materially different from revenue recorded consistent with current practice. Consequently, Con Edison does not anticipate that the new standard will materially impact the amount and/or timing of such revenues. The Companies continue to review the potential impacts of the remaining revenue at the Utilities and the Clean Energy Businesses on the Companies' financial position, results of operations and liquidity as well as the additional disclosures and related controls required under the new standard, and anticipate completing such reviews during the fourth quarter of 2017. In February 2016, the FASB issued amendments on financial reporting of leasing transactions through ASU No. 2016-02, “Leases (Topic 842)." The amendments require lessees to recognize assets and liabilities on the balance sheet and disclose key information about leasing arrangements. Lessees will need to recognize a right-of-use asset and a lease liability for virtually all of their leases (other than leases that meet the definition of a short-term lease). Lessor accounting is similar to the current model, but updated to align with certain changes to the lessee model. For income statement purposes, the pattern of expense recognition will be dependent on whether transactions are designated as operating leases or finance leases. The amendments are effective for reporting periods beginning after December 15, 2018. Early adoption is permitted. The amendments must be adopted using a modified retrospective transition and provide for certain practical expedients. Based on the existing portfolio of leases at implementation, for leases currently classified as operating leases, the Companies expect to recognize on the statements of financial position right-of-use assets and lease liabilities. The Companies are in the process of evaluating the potential impact of the new guidance on the Companies’ results of operations and liquidity. In January 2017, the FASB issued amendments to the guidance for Business Combinations through ASU 2017-01, “Business Combinations (Topic 805): Clarifying the Definition of a Business.” The amendments in this update clarify the definition of a business and provide guidance on evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. For public entities, the amendments are effective for reporting periods beginning after December 15, 2017. Early adoption is permitted. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity. In January 2017, the FASB issued amendments to the guidance for the subsequent measurement of goodwill through ASU 2017-04, “Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” The amendments in this update simplify goodwill impairment testing by eliminating Step 2 of the goodwill impairment test wherein an entity has to compute the implied fair value of goodwill by performing procedures to determine the fair value of its assets and liabilities. Under the new guidance, an entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value up to the total amount of goodwill allocated to that reporting unit. For public entities, the amendments are effective for reporting periods beginning after December 15, 2019. Early adoption is permitted. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity. In February 2017, the FASB issued amendments to the guidance for other income through ASU 2017-05, “Other Income-Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets.” The amendments in this update clarify the scope of assets within Subtopic 610-20 and add guidance for partial sales of nonfinancial assets. The amendments are effective upon the adoption of ASU 2014-09, and therefore will be effective for reporting periods beginning after December 15, 2017. The Company is in the process of evaluating the potential impact of the new guidance on the Company’s financial position, results of operations and liquidity. In March 2017, the FASB issued amendments to the guidance for retirement benefits through ASU 2017-07, “Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.” The amendments in this update modify the presentation of net benefit cost, where the service component must be disaggregated from the other components of net benefit cost and be presented in the same line item as current employee compensation costs. The remaining components of the net benefit cost should be presented outside of income from operations. Additionally, the update allows only the service cost component to be eligible for capitalization. For public entities, the amendments are effective for reporting periods beginning after December 15, 2017. Early adoption is permitted. The Companies are in the process of evaluating the potential impact of the new guidance on the Companies’ financial position, results of operations and liquidity. In March 2017, the FASB issued amendments to the guidance for debt securities through ASU 2017-08, “Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities.” The amendments in this update shorten the amortization period for certain callable debt securities held at a premium. The amendments do not require an accounting change for securities held at a discount; the discount continues to be amortized to maturity. For public entities, the amendments are effective for reporting periods beginning after December 15, 2018. Early adoption is permitted. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity. In May 2017, the FASB issued amendments to the guidance for stock compensation through ASU 2017-09, “Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting.” The amendments in this update specify that changes to value, vesting conditions, or classification of an existing share-based payment award require application of modification accounting in Topic 718. For public entities, the amendments are effective for reporting periods beginning after December 15, 2017. Early adoption is permitted. The application of this guidance is not expected to have a material impact on the Companies’ financial position, results of operations and liquidity. In August 2017, the FASB issued amendments to the guidance for derivatives and hedging through ASU 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities.” The amendments in this update provide greater clarification on hedge accounting for risk components, presentation and disclosure of hedging instruments, and overall targeted improvements to simplify hedge accounting. For public entities, the amendments are effective for reporting periods beginning after December 15, 2018 and interim periods within those fiscal years. Early adoption is permitted. The Companies are in the process of evaluating the potential impact of the new guidance on the Companies’ financial position, results of operations and liquidity.

Summary of Significant Accoun25

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Basic and Diluted Earnings Per Share	For the three and nine months ended September 30, 2017 and 2016 , basic and diluted EPS for Con Edison are calculated as follows: For the Three Months Ended September 30, For the Nine Months Ended September 30, (Millions of Dollars, except per share amounts/Shares in Millions) 2017 2016 2017 2016 Net income $457 $497 $1,020 $1,039 Weighted average common shares outstanding – basic 307.8 304.5 306.2 299.1 Add: Incremental shares attributable to effect of potentially dilutive securities 1.5 1.4 1.5 1.4 Adjusted weighted average common shares outstanding – diluted 309.3 305.9 307.7 300.5 Net Income per common share – basic $1.48 $1.63 $3.33 $3.47 Net Income per common share – diluted $1.48 $1.62 $3.31 $3.46
Changes in Accumulated Other Comprehensive Income/(Loss)	For the three and nine months ended September 30, 2017 and 2016 , changes to accumulated other comprehensive income/(loss) (OCI) for Con Edison and CECONY are as follows: For the Three Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Beginning balance, accumulated OCI, net of taxes (a) $(27) $(33) $(7) $(8) Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax of $(1) for Con Edison in 2017 and 2016 (a)(b) 1 1 1 — Current period OCI, net of taxes 1 1 1 — Ending balance, accumulated OCI, net of taxes $(26) $(32) $(6) $(8) For the Nine Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Beginning balance, accumulated OCI, net of taxes (a) $(27) $(34) $(7) $(9) OCI before reclassifications, net of tax of $1 for Con Edison in 2017 and 2016 (2) (1) — — Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax of $(2) for Con Edison in 2017 and 2016 (a)(b) 3 3 1 1 Current period OCI, net of taxes 1 2 1 1 Ending balance, accumulated OCI, net of taxes $(26) $(32) $(6) $(8) (a) Tax reclassified from accumulated OCI is reported in the income tax expense line item of the consolidated income statement. (b) For the portion of unrecognized pension and other postretirement benefit costs relating to the Utilities, costs are recorded into, and amortized out of, regulatory assets instead of OCI. The net actuarial losses and prior service costs recognized during the period are included in the computation of total periodic pension and other postretirement benefit cost. See Notes E and F.

Regulatory Matters (Tables)

Regulatory Matters (Tables)	9 Months Ended
	Sep. 30, 2017
Regulated Operations [Abstract]
Summary of Utilities Rate Plans	The following table contains a summary of the electric rate plan. RECO Effective period March 2017 (a) Base rate changes Yr. 1 - $1.7 million Amortization to income of net regulatory (assets) and liabilities $0.2 million over three years and continuation of $(25.6) million of deferred storm costs over four years expiring July 31, 2018 (b) Recoverable energy costs Current rate recovery of purchased power costs. Cost reconciliations None Average rate base Yr. 1 - $178.7 million Weighted average cost of capital (after-tax) 7.47 percent Authorized return on common equity 9.6 percent Cost of long-term debt 5.37 percent Common equity ratio 49.7 percent (a) Effective until a new rate plan approved by the NJBPU goes into effect. (b) In January 2016, the NJBPU approved RECO’s plan to spend $15.7 million in capital over three years to harden its electric system against storms, the costs of which RECO, beginning in 2017, is collecting through a customer surcharge.
Schedule of Regulatory Assets	Regulatory assets and liabilities at September 30, 2017 and December 31, 2016 were comprised of the following items: Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Regulatory assets Unrecognized pension and other postretirement costs $2,626 $2,874 $2,476 $2,730 Future income tax 2,419 2,439 2,308 2,325 Environmental remediation costs 803 823 690 711 Revenue taxes 341 295 325 280 Deferred derivative losses 88 48 78 42 Pension and other postretirement benefits deferrals 70 38 45 7 Municipal infrastructure support costs 57 44 57 44 Deferred storm costs 43 56 — 3 Unamortized loss on reacquired debt 39 43 37 41 Indian Point Energy Center program costs 32 50 32 50 O&R property tax reconciliation 29 37 — — Brooklyn Queens demand management program 28 29 28 29 Preferred stock redemption 24 25 24 25 Surcharge for New York State assessment 18 28 16 26 Net electric deferrals 13 24 13 24 Workers’ compensation 12 13 12 13 O&R transition bond charges 10 15 — — Recoverable energy costs 4 42 4 38 Other 113 101 103 85 Regulatory assets – noncurrent 6,769 7,024 6,248 6,473 Deferred derivative losses 81 91 75 86 Recoverable energy costs 28 9 25 4 Regulatory assets – current 109 100 100 90 Total Regulatory Assets $6,878 $7,124 $6,348 $6,563 Regulatory liabilities Allowance for cost of removal less salvage $798 $755 $671 $641 Pension and other postretirement benefit deferrals 202 193 174 162 Net unbilled revenue deferrals 166 145 166 145 Property tax reconciliation 140 178 140 178 Unrecognized other postretirement costs 84 60 84 60 Settlement of prudence proceeding 73 95 73 95 Carrying charges on repair allowance and bonus depreciation 49 68 48 67 New York State income tax rate change 48 61 48 60 Variable-rate tax-exempt debt – cost rate reconciliation 36 55 32 48 Property tax refunds 28 1 28 1 Settlement of gas proceedings 27 27 27 27 Base rate change deferrals 26 40 26 40 Earnings sharing - electric, gas and steam 24 39 15 28 Net utility plant reconciliations 11 16 8 15 Other 161 172 133 145 Regulatory liabilities – noncurrent 1,873 1,905 1,673 1,712 Refundable energy costs 29 29 9 5 Revenue decoupling mechanism 27 71 27 61 Deferred derivative gains 2 28 2 24 Regulatory liabilities – current 58 128 38 90 Total Regulatory Liabilities $1,931 $2,033 $1,711 $1,802
Schedule of Regulatory Liabilities	Regulatory assets and liabilities at September 30, 2017 and December 31, 2016 were comprised of the following items: Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Regulatory assets Unrecognized pension and other postretirement costs $2,626 $2,874 $2,476 $2,730 Future income tax 2,419 2,439 2,308 2,325 Environmental remediation costs 803 823 690 711 Revenue taxes 341 295 325 280 Deferred derivative losses 88 48 78 42 Pension and other postretirement benefits deferrals 70 38 45 7 Municipal infrastructure support costs 57 44 57 44 Deferred storm costs 43 56 — 3 Unamortized loss on reacquired debt 39 43 37 41 Indian Point Energy Center program costs 32 50 32 50 O&R property tax reconciliation 29 37 — — Brooklyn Queens demand management program 28 29 28 29 Preferred stock redemption 24 25 24 25 Surcharge for New York State assessment 18 28 16 26 Net electric deferrals 13 24 13 24 Workers’ compensation 12 13 12 13 O&R transition bond charges 10 15 — — Recoverable energy costs 4 42 4 38 Other 113 101 103 85 Regulatory assets – noncurrent 6,769 7,024 6,248 6,473 Deferred derivative losses 81 91 75 86 Recoverable energy costs 28 9 25 4 Regulatory assets – current 109 100 100 90 Total Regulatory Assets $6,878 $7,124 $6,348 $6,563 Regulatory liabilities Allowance for cost of removal less salvage $798 $755 $671 $641 Pension and other postretirement benefit deferrals 202 193 174 162 Net unbilled revenue deferrals 166 145 166 145 Property tax reconciliation 140 178 140 178 Unrecognized other postretirement costs 84 60 84 60 Settlement of prudence proceeding 73 95 73 95 Carrying charges on repair allowance and bonus depreciation 49 68 48 67 New York State income tax rate change 48 61 48 60 Variable-rate tax-exempt debt – cost rate reconciliation 36 55 32 48 Property tax refunds 28 1 28 1 Settlement of gas proceedings 27 27 27 27 Base rate change deferrals 26 40 26 40 Earnings sharing - electric, gas and steam 24 39 15 28 Net utility plant reconciliations 11 16 8 15 Other 161 172 133 145 Regulatory liabilities – noncurrent 1,873 1,905 1,673 1,712 Refundable energy costs 29 29 9 5 Revenue decoupling mechanism 27 71 27 61 Deferred derivative gains 2 28 2 24 Regulatory liabilities – current 58 128 38 90 Total Regulatory Liabilities $1,931 $2,033 $1,711 $1,802

Capitalization (Tables)

Capitalization (Tables)	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Carrying Amounts and Fair Values of Long-Term Debt	The carrying amounts and fair values of long-term debt at September 30, 2017 and December 31, 2016 were: (Millions of Dollars) 2017 2016 Long-Term Debt (including current portion) (a) Carrying Amount Fair Value Carrying Amount Fair Value Con Edison $15,338 $17,195 $14,774 $16,093 CECONY $12,571 $14,213 $12,073 $13,268 (a) Amounts shown are net of unamortized debt expense and unamortized debt discount of $137 million and $115 million for Con Edison and CECONY, respectively, as of September 30, 2017 and $134 million and $113 million for Con Edison and CECONY, respectively, as of December 31, 2016 .

Pension Benefits (Tables)

Pension Benefits (Tables)	9 Months Ended
	Sep. 30, 2017
Retirement Benefits [Abstract]
Total Periodic Benefit Costs	The components of the Companies’ total periodic benefit costs for the three and nine months ended September 30, 2017 and 2016 were as follows: For the Three Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Service cost – including administrative expenses $66 $69 $61 $65 Interest cost on projected benefit obligation 148 149 139 140 Expected return on plan assets (243) (237) (229) (225) Recognition of net actuarial loss 149 149 141 141 Recognition of prior service costs (4) 1 (5) — TOTAL PERIODIC BENEFIT COST $116 $131 $107 $121 Cost capitalized (40) (51) (37) (49) Reconciliation to rate level (14) 10 (16) 13 Cost charged to operating expenses $62 $90 $54 $85 For the Nine Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Service cost – including administrative expenses $197 $207 $184 $194 Interest cost on projected benefit obligation 444 447 416 419 Expected return on plan assets (726) (711) (689) (674) Recognition of net actuarial loss 446 447 423 424 Recognition of prior service costs (13) 3 (14) 1 TOTAL PERIODIC BENEFIT COST $348 $393 $320 $364 Cost capitalized (134) (157) (125) (148) Reconciliation to rate level (28) 35 (32) 39 Cost charged to operating expenses $186 $271 $163 $255 The components of the Companies’ total periodic other postretirement benefit costs for the three and nine months ended September 30, 2017 and 2016 were as follows: For the Three Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Service cost $5 $4 $3 $3 Interest cost on accumulated other postretirement benefit obligation 11 12 9 10 Expected return on plan assets (17) (19) (15) (17) Recognition of net actuarial loss 1 1 — 1 Recognition of prior service cost (5) (5) (3) (3) TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST $(5) $(7) $(6) $(6) Cost capitalized 2 2 2 2 Reconciliation to rate level (1) 7 — 6 Cost charged to operating expenses $(4) $2 $(4) $2 For the Nine Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Service cost $15 $13 $10 $10 Interest cost on accumulated other postretirement benefit obligation 34 36 28 30 Expected return on plan assets (52) (58) (45) (50) Recognition of net actuarial loss/(gain) 2 4 (2) 2 Recognition of prior service cost (13) (15) (9) (11) TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST $(14) $(20) $(18) $(19) Cost capitalized 6 5 7 5 Reconciliation to rate level (3) 20 (1) 19 Cost charged to operating expenses $(11) $5 $(12) $5

Other Postretirement Benefits (

Other Postretirement Benefits (Tables)	9 Months Ended
	Sep. 30, 2017
Retirement Benefits [Abstract]
Total Periodic Benefit Costs	The components of the Companies’ total periodic benefit costs for the three and nine months ended September 30, 2017 and 2016 were as follows: For the Three Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Service cost – including administrative expenses $66 $69 $61 $65 Interest cost on projected benefit obligation 148 149 139 140 Expected return on plan assets (243) (237) (229) (225) Recognition of net actuarial loss 149 149 141 141 Recognition of prior service costs (4) 1 (5) — TOTAL PERIODIC BENEFIT COST $116 $131 $107 $121 Cost capitalized (40) (51) (37) (49) Reconciliation to rate level (14) 10 (16) 13 Cost charged to operating expenses $62 $90 $54 $85 For the Nine Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Service cost – including administrative expenses $197 $207 $184 $194 Interest cost on projected benefit obligation 444 447 416 419 Expected return on plan assets (726) (711) (689) (674) Recognition of net actuarial loss 446 447 423 424 Recognition of prior service costs (13) 3 (14) 1 TOTAL PERIODIC BENEFIT COST $348 $393 $320 $364 Cost capitalized (134) (157) (125) (148) Reconciliation to rate level (28) 35 (32) 39 Cost charged to operating expenses $186 $271 $163 $255 The components of the Companies’ total periodic other postretirement benefit costs for the three and nine months ended September 30, 2017 and 2016 were as follows: For the Three Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Service cost $5 $4 $3 $3 Interest cost on accumulated other postretirement benefit obligation 11 12 9 10 Expected return on plan assets (17) (19) (15) (17) Recognition of net actuarial loss 1 1 — 1 Recognition of prior service cost (5) (5) (3) (3) TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST $(5) $(7) $(6) $(6) Cost capitalized 2 2 2 2 Reconciliation to rate level (1) 7 — 6 Cost charged to operating expenses $(4) $2 $(4) $2 For the Nine Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Service cost $15 $13 $10 $10 Interest cost on accumulated other postretirement benefit obligation 34 36 28 30 Expected return on plan assets (52) (58) (45) (50) Recognition of net actuarial loss/(gain) 2 4 (2) 2 Recognition of prior service cost (13) (15) (9) (11) TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST $(14) $(20) $(18) $(19) Cost capitalized 6 5 7 5 Reconciliation to rate level (3) 20 (1) 19 Cost charged to operating expenses $(11) $5 $(12) $5

Environmental Matters (Tables)

Environmental Matters (Tables)	9 Months Ended
	Sep. 30, 2017
Environmental Remediation Obligations [Abstract]
Accrued Liabilities and Regulatory Assets	The accrued liabilities and regulatory assets related to Superfund Sites at September 30, 2017 and December 31, 2016 were as follows: Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Accrued Liabilities: Manufactured gas plant sites $659 $664 $563 $567 Other Superfund Sites 86 89 85 88 Total $745 $753 $648 $655 Regulatory assets $803 $823 $690 $711
Environmental Remediation Costs	Environmental remediation costs incurred related to Superfund Sites for the three and nine months ended September 30, 2017 and 2016 were as follows: For the Three Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Remediation costs incurred $4 $8 $3 $5 For the Nine Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Remediation costs incurred $18 $20 $13 $10
Accrued Liability for Asbestos Suits and Workers' Compensation Proceedings	The accrued liability for asbestos suits and workers’ compensation proceedings (including those related to asbestos exposure) and the amounts deferred as regulatory assets for the Companies at September 30, 2017 and December 31, 2016 were as follows: Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Accrued liability – asbestos suits $8 $8 $7 $7 Regulatory assets – asbestos suits $8 $8 $7 $7 Accrued liability – workers’ compensation $87 $88 $83 $83 Regulatory assets – workers’ compensation $12 $13 $12 $13

Other Material Contingencies (T

Other Material Contingencies (Tables)	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Summary of Total Guarantees	A summary, by type and term, of Con Edison’s total guarantees at September 30, 2017 is as follows: Guarantee Type 0 – 3 years 4 – 10 years > 10 years Total (Millions of Dollars) Con Edison Transmission $643 $404 $— $1,047 Energy transactions 459 30 211 700 Renewable electric production projects 268 — 19 287 Other 128 — — 128 Total $1,498 $434 $230 $2,162

Financial Information by Busi32

Financial Information by Business Segment (Tables)	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Financial Data for Business Segments	The financial data for the business segments for the three and nine months ended September 30, 2017 and 2016 were as follows: For the Three Months Ended September 30, Operating revenues Inter-segment revenues Depreciation and amortization Operating income/(loss) (Millions of Dollars) 2017 2016 2017 2016 2017 2016 2017 2016 CECONY Electric $2,469 $2,557 $4 $5 $232 $217 $855 $841 Gas 268 208 2 1 47 41 (12) (28) Steam 62 63 19 22 21 20 (43) (47) Consolidation adjustments — — (25) (28) — — — — Total CECONY $2,799 $2,828 $— $— $300 $278 $800 $766 O&R Electric $206 $213 $— $— $13 $12 $56 $55 Gas 28 27 — — 5 5 (11) (7) Total O&R $234 $240 $— $— $18 $17 $45 $48 Clean Energy Businesses $177 $350 $— $(2) $19 $11 $29 $125 Con Edison Transmission 1 — — — — — (2) (1) Other (a) — (1) — 2 — (1) 1 2 Total Con Edison $3,211 $3,417 $— $— $337 $305 $873 $940 For the Nine Months Ended September 30, Operating revenues Inter-segment revenues Depreciation and amortization Operating income/(loss) (Millions of Dollars) 2017 2016 2017 2016 2017 2016 2017 2016 CECONY Electric $6,079 $6,222 $12 $13 $690 $645 $1,477 $1,487 Gas 1,421 1,113 5 4 137 118 362 273 Steam 448 406 55 65 64 62 52 39 Consolidation adjustments — — (72) (82) — — — — Total CECONY $7,948 $7,741 $— $— $891 $825 $1,891 $1,799 O&R Electric $495 $497 $— $— $38 $37 $83 $86 Gas 172 133 — — 15 13 33 28 Total O&R $667 $630 $— $— $53 $50 $116 $114 Clean Energy Businesses $460 $998 $— $7 $54 $30 $63 $184 Con Edison Transmission 1 — — — — — (6) (1) Other (a) (4) (1) — (7) — — 2 1 Total Con Edison $9,072 $9,368 $— $— $998 $905 $2,066 $2,097 (a) Parent company and consolidation adjustments. Other does not represent a business segment.

Derivative Instruments and He33

Derivative Instruments and Hedging Activities (Tables)	9 Months Ended
	Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Offsetting of Liabilities	The fair values of the Companies’ commodity derivatives including the offsetting of assets and liabilities on the consolidated balance sheet at September 30, 2017 and December 31, 2016 were: (Millions of Dollars) 2017 2016 Balance Sheet Location Gross Amounts of Recognized Assets/(Liabilities) Gross Amounts Offset Net Amounts of Assets/ (Liabilities) (a) Gross Amounts of Recognized Assets/(Liabilities) Gross Amounts Offset Net Amounts of Assets/ (Liabilities) (a) Con Edison Fair value of derivative assets Current $77 $(67) $10 (b) $81 $(64) $17 (b) Noncurrent 64 (61) 3 49 (43) 6 Total fair value of derivative assets $141 $(128) $13 $130 $(107) $23 Fair value of derivative liabilities Current $(141) $71 $(70) $(138) $61 $(77) Noncurrent (143) 60 (83) (91) 52 (39) (c) Total fair value of derivative liabilities $(284) $131 $(153) $(229) $113 $(116) Net fair value derivative assets/(liabilities) $(143) $3 $(140) (b) $(99) $6 $(93) (b) (c) CECONY Fair value of derivative assets Current $55 $(53) $2 (b) $52 $(45) $7 (b) Noncurrent 57 (55) 2 41 (35) 6 Total fair value of derivative assets $112 $(108) $4 $93 $(80) $13 Fair value of derivative liabilities Current $(116) $57 $(59) $(111) $45 $(66) Noncurrent (127) 54 (73) (77) 44 (33) Total fair value of derivative liabilities $(243) $111 $(132) $(188) $89 $(99) Net fair value derivative assets/(liabilities) $(131) $3 $(128) (b) $(95) $9 $(86) (b) (a) Derivative instruments and collateral were offset on the consolidated balance sheet as applicable under the accounting rules. The Companies enter into master agreements for their commodity derivatives. These agreements typically provide offset in the event of contract termination. In such case, generally the non-defaulting party’s payable will be offset by the defaulting party’s payable. The non-defaulting party will customarily notify the defaulting party within a specific time period and come to an agreement on the early termination amount. (b) At September 30, 2017 and December 31, 2016 , margin deposits for Con Edison ( $5 million and $7 million , respectively) and CECONY ( $5 million and $7 million , respectively) were classified as derivative assets on the consolidated balance sheet, but not included in the table. Margin is collateral, typically cash, that the holder of a derivative instrument is required to deposit in order to transact on an exchange and to cover its potential losses with its broker or the exchange. (c) Does not include $(1) million for interest rate swap.
Offsetting of Assets	The fair values of the Companies’ commodity derivatives including the offsetting of assets and liabilities on the consolidated balance sheet at September 30, 2017 and December 31, 2016 were: (Millions of Dollars) 2017 2016 Balance Sheet Location Gross Amounts of Recognized Assets/(Liabilities) Gross Amounts Offset Net Amounts of Assets/ (Liabilities) (a) Gross Amounts of Recognized Assets/(Liabilities) Gross Amounts Offset Net Amounts of Assets/ (Liabilities) (a) Con Edison Fair value of derivative assets Current $77 $(67) $10 (b) $81 $(64) $17 (b) Noncurrent 64 (61) 3 49 (43) 6 Total fair value of derivative assets $141 $(128) $13 $130 $(107) $23 Fair value of derivative liabilities Current $(141) $71 $(70) $(138) $61 $(77) Noncurrent (143) 60 (83) (91) 52 (39) (c) Total fair value of derivative liabilities $(284) $131 $(153) $(229) $113 $(116) Net fair value derivative assets/(liabilities) $(143) $3 $(140) (b) $(99) $6 $(93) (b) (c) CECONY Fair value of derivative assets Current $55 $(53) $2 (b) $52 $(45) $7 (b) Noncurrent 57 (55) 2 41 (35) 6 Total fair value of derivative assets $112 $(108) $4 $93 $(80) $13 Fair value of derivative liabilities Current $(116) $57 $(59) $(111) $45 $(66) Noncurrent (127) 54 (73) (77) 44 (33) Total fair value of derivative liabilities $(243) $111 $(132) $(188) $89 $(99) Net fair value derivative assets/(liabilities) $(131) $3 $(128) (b) $(95) $9 $(86) (b) (a) Derivative instruments and collateral were offset on the consolidated balance sheet as applicable under the accounting rules. The Companies enter into master agreements for their commodity derivatives. These agreements typically provide offset in the event of contract termination. In such case, generally the non-defaulting party’s payable will be offset by the defaulting party’s payable. The non-defaulting party will customarily notify the defaulting party within a specific time period and come to an agreement on the early termination amount. (b) At September 30, 2017 and December 31, 2016 , margin deposits for Con Edison ( $5 million and $7 million , respectively) and CECONY ( $5 million and $7 million , respectively) were classified as derivative assets on the consolidated balance sheet, but not included in the table. Margin is collateral, typically cash, that the holder of a derivative instrument is required to deposit in order to transact on an exchange and to cover its potential losses with its broker or the exchange. (c) Does not include $(1) million for interest rate swap.
Realized and Unrealized Gains or Losses on Commodity Derivatives	The following table presents the realized and unrealized gains or losses on commodity derivatives that have been deferred or recognized in earnings for the three and nine months ended September 30, 2017 and 2016 : For the Three Months Ended September 30, Con Edison CECONY (Millions of Dollars) Balance Sheet Location 2017 2016 2017 2016 Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations: Current Deferred derivative gains $(4) $(1) $(3) $(3) Noncurrent Deferred derivative gains 1 (2) 1 — Total deferred gains/(losses) $(3) $(3) $(2) $(3) Current Deferred derivative losses $(11) $(19) $(9) $(18) Current Recoverable energy costs (40) (39) (38) (35) Noncurrent Deferred derivative losses (12) (17) (8) (14) Total deferred gains/(losses) $(63) $(75) $(55) $(67) Net deferred gains/(losses) $(66) $(78) $(57) $(70) Income Statement Location Pre-tax gains/(losses) recognized in income Purchased power expense $— $(37) (b) $— $— Gas purchased for resale (47) (38) — — Non-utility revenue 5 (a) (2) (b) — — Total pre-tax gains/(losses) recognized in income $(42) $(77) $— $— (a) For the three months ended September 30, 2017 , Con Edison recorded an unrealized pre-tax gain in non-utility operating revenue ( $6 million ). (b) For the three months ended September 30, 2016 , Con Edison recorded unrealized pre-tax losses in non-utility operating revenue ( $2 million ) and purchased power expense ( $23 million ). For the Nine Months Ended September 30, Con Edison CECONY (Millions of Dollars) Balance Sheet Location 2017 2016 2017 2016 Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations: Current Deferred derivative gains $(26) $6 $(22) $2 Noncurrent Deferred derivative gains (2) (1) (2) (1) Total deferred gains/(losses) $(28) $5 $(24) $1 Current Deferred derivative losses $10 $19 $11 $16 Current Recoverable energy costs (125) (163) (116) (148) Noncurrent Deferred derivative losses (40) (5) (36) (3) Total deferred gains/(losses) $(155) $(149) $(141) $(135) Net deferred gains/(losses) $(183) $(144) $(165) $(134) Income Statement Location Pre-tax gains/(losses) recognized in income Purchased power expense $— $(106) (b) $— $— Gas purchased for resale (161) (72) — — Non-utility revenue 11 (a) 15 (b) — — Total pre-tax gains/(losses) recognized in income $(150) $(163) $— $— (a) For the nine months ended September 30, 2017 , Con Edison recorded an unrealized pre-tax gain in non-utility operating revenue ( $2 million ). (b) For the nine months ended September 30, 2016 , Con Edison recorded unrealized pre-tax gains and losses in non-utility operating revenue ( $3 million loss) and purchased power expense ( $11 million gain).
Hedged Volume of Derivative Transactions	The following table presents the hedged volume of Con Edison’s and CECONY’s derivative transactions at September 30, 2017 : Electric Energy (MWh) (a)(b) Capacity (MW) (a) Natural Gas (Dt) (a)(b) Refined Fuels (gallons) Con Edison 32,596,372 6,790 166,913,644 672,000 CECONY 30,492,575 3,000 158,500,000 672,000 (a) Volumes are reported net of long and short positions, except natural gas collars where the volumes of long positions are reported. (b) Excludes electric congestion and gas basis swap contracts, which are associated with electric and gas contracts and hedged volumes.
Aggregate Fair Value of Companies' Derivative Instruments with Credit-Risk-Related Contingent Features	The following table presents the aggregate fair value of the Companies’ derivative instruments with credit-risk-related contingent features that are in a net liability position, the collateral posted for such positions and the additional collateral that would have been required to be posted had the lowest applicable credit rating been reduced one level and to below investment grade at September 30, 2017 : (Millions of Dollars) Con Edison (a) CECONY (a) Aggregate fair value – net liabilities $148 $131 Collateral posted 61 56 Additional collateral (b) (downgrade one level from current ratings) 23 22 Additional collateral (b) (downgrade to below investment grade from current ratings) 101 (c) 88 (c) (a) Non-derivative transactions for the purchase and sale of electricity and gas and qualifying derivative instruments, which have been designated as normal purchases or normal sales, are excluded from the table. These transactions primarily include purchases of electricity from independent system operators. In the event the Utilities and the Clean Energy Businesses were no longer extended unsecured credit for such purchases, the Companies would be required to post additional collateral of $11 million at September 30, 2017 . For certain other such non-derivative transactions, the Companies could be required to post collateral under certain circumstances, including in the event counterparties had reasonable grounds for insecurity. (b) The Companies measure the collateral requirements by taking into consideration the fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position plus amounts owed to counterparties for settled transactions and amounts required by counterparties for minimum financial security. The fair value amounts represent unrealized losses, net of any unrealized gains where the Companies have a legally enforceable right to offset. (c) Derivative instruments that are net assets have been excluded from the table. At September 30, 2017 , if Con Edison had been downgraded to below investment grade, it would have been required to post additional collateral for such derivative instruments of $13 million .

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on Recurring Basis	Assets and liabilities measured at fair value on a recurring basis as of September 30, 2017 and December 31, 2016 are summarized below. 2017 2016 (Millions of Dollars) Level 1 Level 2 Level 3 Netting Adjustment (e) Total Level 1 Level 2 Level 3 Netting Adjustment (e) Total Con Edison Derivative assets: Commodity (a)(b)(c) $6 $28 $2 $(18) $18 $14 $33 $7 $(24) $30 Other (a)(b)(d) 271 118 — — 389 222 111 — — 333 Total assets $277 $146 $2 $(18) $407 $236 $144 $7 $(24) $363 Derivative liabilities: Commodity (a)(b)(c) $2 $155 $22 $(26) $153 $4 $144 $6 $(38) $116 Interest Rate Swap (a)(b)(c) — — — — — — 1 — — 1 Total liabilities $2 $155 $22 $(26) $153 $4 $145 $6 $(38) $117 CECONY Derivative assets: Commodity (a)(b)(c) $5 $12 $1 $(9) $9 $10 $19 $1 $(10) $20 Other (a)(b)(d) 248 113 — — 361 200 106 — — 306 Total assets $253 $125 $1 $(9) $370 $210 $125 $1 $(10) $326 Derivative liabilities: Commodity (a)(b)(c) $1 $133 $15 $(17) $132 $1 $124 $— $(26) $99 (a) The Companies’ policy is to review the fair value hierarchy and recognize transfers into and transfers out of the levels at the end of each reporting period. There were no transfers between levels 1, 2 and 3 for the nine months ended September 30, 2017 and for the year ended December 31, 2016 . (b) Level 2 assets and liabilities include investments held in the deferred compensation plan and/or non-qualified retirement plans, exchange-traded contracts where there is insufficient market liquidity to warrant inclusion in Level 1, certain over-the-counter derivative instruments for electricity, refined products and natural gas. Derivative instruments classified as Level 2 are valued using industry standard models that incorporate corroborated observable inputs; such as pricing services or prices from similar instruments that trade in liquid markets, time value and volatility factors. (c) The accounting rules for fair value measurements and disclosures require consideration of the impact of nonperformance risk (including credit risk) from a market participant perspective in the measurement of the fair value of assets and liabilities. At September 30, 2017 and December 31, 2016 , the Companies determined that nonperformance risk would have no material impact on their financial position or results of operations. (d) Other assets are comprised of assets such as life insurance contracts within the deferred compensation plan and non-qualified retirement plans. (e) Amounts represent the impact of legally-enforceable master netting agreements that allow the Companies to net gain and loss positions and cash collateral held or placed with the same counterparties.
Schedule of Commodity Derivatives	Fair Value of Level 3 at September 30, 2017 Valuation Techniques Unobservable Inputs Range (Millions of Dollars) Con Edison – Commodity Electricity $(21) Discounted Cash Flow Forward energy prices (a) $19.00-$76.25 per MWh Discounted Cash Flow Forward capacity prices (a) $1.26-$9.47 per kW-month Transmission Congestion Contracts/Financial Transmission Rights 1 Discounted Cash Flow Discount to adjust auction prices for inter-zonal forward price curves (b) 50.0% Inter-zonal forward price curves adjusted for historical zonal losses (b) $0.50-$6.75 per MWh Total Con Edison—Commodity $(20) CECONY – Commodity Electricity $(15) Discounted Cash Flow Forward energy prices (a) $20.50-$76.25 per MWh Transmission Congestion Contracts 1 Discounted Cash Flow Discount to adjust auction prices for inter-zonal forward price curves (b) 50.0% Total CECONY—Commodity $(14) (a) Generally, increases/(decreases) in this input in isolation would result in a higher/(lower) fair value measurement. (b) Generally, increases/(decreases) in this input in isolation would result in a lower/(higher) fair value measurement.
Reconciliation of Beginning and Ending Net Balances for Assets and Liabilities Measured at Level 3 Fair Value	The table listed below provides a reconciliation of the beginning and ending net balances for assets and liabilities measured at fair value as of September 30, 2017 and 2016 and classified as Level 3 in the fair value hierarchy: For the Three Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Beginning balance as of July 1, $(10) $5 $(6) $2 Included in earnings 7 (4) 1 — Included in regulatory assets and liabilities (13) (5) (8) (3) Sales — 4 — — Settlements (4) 1 (1) 1 Ending balance as of September 30, $(20) $1 $(14) $— For the Nine Months Ended September 30, Con Edison CECONY (Millions of Dollars) 2017 2016 2017 2016 Beginning balance as of January 1, $1 $6 $1 $8 Included in earnings 8 (1) 1 (1) Included in regulatory assets and liabilities (21) (11) (14) (6) Purchases 1 2 1 1 Sales — 4 — — Settlements (9) 1 (3) (2) Ending balance as of September 30, $(20) $1 $(14) $—

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	9 Months Ended
	Sep. 30, 2017
Equity Method Investments and Joint Ventures [Abstract]
Summary of VIEs	The following table summarizes the VIEs in which Con Edison Development has entered into as of September 30, 2017 : Project Name (a) Generating Capacity (b) (MW AC) Power Purchase Agreement Term (in Years) Year of Initial Investment Location Maximum Exposure to Loss ( Millions of Dollars ) (c) Copper Mountain Solar 3 128 20 2014 Nevada $175 Mesquite Solar 1 83 20 2013 Arizona 102 Copper Mountain Solar 2 75 25 2013 Nevada 83 California Solar 55 25 2012 California 64 Broken Bow II 38 25 2014 Nebraska 44 Texas Solar 4 32 25 2014 Texas 47 (a) With the exception of Texas Solar 4, Con Edison’s ownership interest is 50 percent and these projects are accounted for using the equity method of accounting. With the exception of Texas Solar 4, Con Edison is not the primary beneficiary since the power to direct the activities that most significantly impact the economics of the entities are shared equally between Con Edison Development and third parties. Con Edison’s ownership interest in Texas Solar 4 is 80 percent and is consolidated in the financial statements. Con Edison is the primary beneficiary since the power to direct the activities that most significantly impact the economics of Texas Solar 4 is held by Con Edison Development. (b) Represents Con Edison Development’s ownership interest in the project. (c) For investments accounted for under the equity method, maximum exposure is equal to the carrying value of the investment on the consolidated balance sheet. For consolidated investments, such as Texas Solar 4, maximum exposure is equal to the net assets of the project on the consolidated balance sheet less any applicable noncontrolling interest ( $7 million for Texas Solar 4). Con Edison did not provide any financial or other support during the three and nine months ended September 30, 2017 that was not previously contractually required.

General (Details)

General (Details)	9 Months Ended
	Sep. 30, 2017subsidiaryregistrant
Accounting Policies [Abstract]
Number of registrants | registrant	2
Number of regulated utility subsidiaries	2
Clean Energy Businesses
Investment [Line Items]
Number of subsidiaries	3

Summary of Significant Accoun37

Summary of Significant Accounting Policies - Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016
Accounting Policies [Abstract]
Net income	$ 457	$ 175	$ 388	$ 497	$ 232	$ 310	$ 1,020	$ 1,039
Weighted average common shares outstanding – basic	307.8			304.5			306.2	299.1
Add: Incremental shares attributable to effect of potentially dilutive securities	1.5			1.4			1.5	1.4
Adjusted weighted average common shares outstanding – diluted	309.3			305.9			307.7	300.5
Net income per common share-basic (dollars per share)	$ 1.48			$ 1.63			$ 3.33	$ 3.47
Net income per common share-diluted (dollars per share)	$ 1.48			$ 1.62			$ 3.31	$ 3.46

Summary of Significant Accoun38

Summary of Significant Accounting Policies - Changes in Accumulated Other Comprehensive Income/(Loss) by Component (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 14,498	$ 14,506	$ 14,306	$ 13,958	$ 13,201	$ 13,061	$ 14,306	$ 13,061
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	1	1	(1)	1	1	0	1	2
Ending Balance	15,110	14,498	14,506	14,275	13,958	13,201	15,110	14,275
Accumulated OCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(27)	(28)	(27)	(33)	(34)	(34)	(27)	(34)
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	1	1	(1)	1	1
Ending Balance	(26)	(27)	(28)	(32)	(33)	(34)	(26)	(32)
Pension Plan Liabilities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
OCI before reclassifications, net of tax of $1 for Con Edison in 2017 and 2016							(2)	(1)
Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax	1			1			3	3
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	1			1			1	2
OCI before reclassifications, tax							1	1
Amounts reclassified from accumulated OCI related to pension plan liabilities, tax	(1)			(1)			(2)	(2)
CECONY
AOCI Attributable to Parent, Net of Tax [Roll Forward]
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	1	0	0	0	1	0	1	1
CECONY | Accumulated OCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(7)		(7)	(8)		(9)	(7)	(9)
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	1	0	$ 0	0	1	$ 0
Ending Balance	(6)	$ (7)		(8)	$ (8)		(6)	(8)
CECONY | Pension Plan Liabilities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
OCI before reclassifications, net of tax of $1 for Con Edison in 2017 and 2016							0	0
Amounts reclassified from accumulated OCI related to pension plan liabilities, net of tax	1			0			1	1
TOTAL OTHER COMPREHENSIVE INCOME, NET OF TAXES	$ 1			$ 0			$ 1	$ 1

Regulatory Matters - Summary of

Regulatory Matters - Summary of Utilities Rate Plans (Details) - Rockland Electric Company (RECO) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Jan. 31, 2016	Sep. 30, 2017
Public Utilities, General Disclosures [Line Items]
Base rate changes		$ 1.7
Amortization to income of net regulatory liabilities		$ 0.2
Regulatory liabilities, amortization period		3 years
Amortization to income of net regulatory assets		$ (25.6)
Regulatory assets, amortization period		4 years
Average rate base		$ 178.7
Weighted average cost of capital (after-tax) (percent)		7.47%
Authorized return on common equity (percent)		9.60%
Cost of long-term debt (percent)		5.37%
Common equity ratio (percent)		49.70%
Electric
Public Utilities, General Disclosures [Line Items]
Plan electric system storm hardening amount	$ 15.7
Plan period (years)	3 years

Regulatory Matters - Additional

Regulatory Matters - Additional Information (Details) - FERC - USD ($) $ in Millions	1 Months Ended		3 Months Ended
	Sep. 30, 2017	Apr. 30, 2017	Mar. 31, 2017
Public Utilities, General Disclosures [Line Items]
Requested return on equity (percent)	10.00%
RECO
Public Utilities, General Disclosures [Line Items]
Requested rate increase, amount		$ 17.7	$ 11.8

Regulatory Matters - Regulatory

Regulatory Matters - Regulatory Assets (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	$ 6,769	$ 7,024
Regulatory assets – current	109	100
Total Regulatory Assets	6,878	7,124
Unrecognized pension and other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	2,626	2,874
Future income tax
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	2,419	2,439
Environmental remediation costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	803	823
Revenue taxes
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	341	295
Deferred derivative losses
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	88	48
Pension and other postretirement benefits deferrals
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	70	38
Municipal infrastructure support costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	57	44
Deferred storm costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	43	56
Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	39	43
Indian Point Energy Center program costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	32	50
O&R property tax reconciliation
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	29	37
Brooklyn Queens demand management program
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	28	29
Preferred stock redemption
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	24	25
Surcharge for New York State assessment
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	18	28
Net electric deferrals
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	13	24
Workers’ compensation
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	12	13
O&R transition bond charges
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	10	15
Recoverable energy costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	4	42
Regulatory assets – current	28	9
Other
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	113	101
Deferred derivative losses
Regulatory Assets [Line Items]
Regulatory assets – current	81	91
CECONY
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	6,248	6,473
Regulatory assets – current	100	90
Total Regulatory Assets	6,348	6,563
CECONY | Unrecognized pension and other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	2,476	2,730
CECONY | Future income tax
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	2,308	2,325
CECONY | Environmental remediation costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	690	711
CECONY | Revenue taxes
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	325	280
CECONY | Deferred derivative losses
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	78	42
CECONY | Pension and other postretirement benefits deferrals
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	45	7
CECONY | Municipal infrastructure support costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	57	44
CECONY | Deferred storm costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	0	3
CECONY | Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	37	41
CECONY | Indian Point Energy Center program costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	32	50
CECONY | O&R property tax reconciliation
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	0	0
CECONY | Brooklyn Queens demand management program
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	28	29
CECONY | Preferred stock redemption
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	24	25
CECONY | Surcharge for New York State assessment
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	16	26
CECONY | Net electric deferrals
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	13	24
CECONY | Workers’ compensation
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	12	13
CECONY | O&R transition bond charges
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	0	0
CECONY | Recoverable energy costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	4	38
Regulatory assets – current	25	4
CECONY | Other
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	103	85
CECONY | Deferred derivative losses
Regulatory Assets [Line Items]
Regulatory assets – current	$ 75	$ 86

Regulatory Matters - Regulato42

Regulatory Matters - Regulatory Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	$ 1,873	$ 1,905
Regulatory liabilities – current	58	128
Total Regulatory Liabilities	1,931	2,033
Allowance for cost of removal less salvage
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	798	755
Pension and other postretirement benefit deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	202	193
Net unbilled revenue deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	166	145
Property tax reconciliation
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	140	178
Unrecognized other postretirement costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	84	60
Settlement of prudence proceeding
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	73	95
Carrying charges on repair allowance and bonus depreciation
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	49	68
New York State income tax rate change
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	48	61
Variable-rate tax-exempt debt – cost rate reconciliation
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	36	55
Property tax refunds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	28	1
Settlement of gas proceedings
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	27	27
Base rate change deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	26	40
Earnings sharing - electric, gas and steam
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	24	39
Net utility plant reconciliations
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	11	16
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	161	172
Refundable energy costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	29	29
Revenue decoupling mechanism
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	27	71
Deferred derivative gains
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	2	28
CECONY
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,673	1,712
Regulatory liabilities – current	38	90
Total Regulatory Liabilities	1,711	1,802
CECONY | Allowance for cost of removal less salvage
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	671	641
CECONY | Pension and other postretirement benefit deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	174	162
CECONY | Net unbilled revenue deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	166	145
CECONY | Property tax reconciliation
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	140	178
CECONY | Unrecognized other postretirement costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	84	60
CECONY | Settlement of prudence proceeding
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	73	95
CECONY | Carrying charges on repair allowance and bonus depreciation
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	48	67
CECONY | New York State income tax rate change
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	48	60
CECONY | Variable-rate tax-exempt debt – cost rate reconciliation
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	32	48
CECONY | Property tax refunds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	28	1
CECONY | Settlement of gas proceedings
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	27	27
CECONY | Base rate change deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	26	40
CECONY | Earnings sharing - electric, gas and steam
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	15	28
CECONY | Net utility plant reconciliations
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	8	15
CECONY | Other
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	133	145
CECONY | Refundable energy costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	9	5
CECONY | Revenue decoupling mechanism
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	27	61
CECONY | Deferred derivative gains
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	$ 2	$ 24

Capitalization - Additional Inf

Capitalization - Additional Information (Details) - USD ($) shares in Millions	1 Months Ended		9 Months Ended
	Aug. 31, 2017	Mar. 31, 2017	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017
Schedule of Capitalization [Line Items]
Number of common shares issued	4.1
Proceeds from common shares issued	$ 343,000,000		$ 37,000,000	$ 38,000,000
Level 2
Schedule of Capitalization [Line Items]
Long-term debt, fair value			16,559,000,000
Level 3
Schedule of Capitalization [Line Items]
Long-term debt, fair value			636,000,000
CECONY | Level 2
Schedule of Capitalization [Line Items]
Long-term debt, fair value			13,577,000,000
CECONY | Level 3
Schedule of Capitalization [Line Items]
Long-term debt, fair value			636,000,000
Tax-exempt debt			$ 636,000,000
Variable Rate Term Loan Due 2018 | Term Loan
Schedule of Capitalization [Line Items]
Amount of debt prepaid		$ 400,000,000
Debentures | 2.00% Debentures Due 2020
Schedule of Capitalization [Line Items]
Debt Instrument, face amount		$ 400,000,000
Debt instrument, interest rate		2.00%
Debentures | 3.875% Debentures Due 2047 | CECONY
Schedule of Capitalization [Line Items]
Debt Instrument, face amount					$ 500,000,000
Debt instrument, interest rate					3.875%
Senior Notes | 4.45% Senior Notes Due 2042 | Con Edison Development
Schedule of Capitalization [Line Items]
Debt Instrument, face amount		$ 97,000,000
Debt instrument, interest rate		4.45%

Capitalization - Carrying Amoun

Capitalization - Carrying Amounts and Fair Values of Long-Term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Unamortized debt expense	$ 137	$ 134
Carrying Amount
Debt Instrument [Line Items]
Long-Term Debt (including current portion)	15,338	14,774
Fair Value
Debt Instrument [Line Items]
Long-Term Debt (including current portion)	17,195	16,093
CECONY
Debt Instrument [Line Items]
Unamortized debt discount	115	113
CECONY | Carrying Amount
Debt Instrument [Line Items]
Long-Term Debt (including current portion)	12,571	12,073
CECONY | Fair Value
Debt Instrument [Line Items]
Long-Term Debt (including current portion)	$ 14,213	$ 13,268

Short-Term Borrowing (Details)

Short-Term Borrowing (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Short-term Debt [Line Items]
Commercial paper, outstanding	$ 356,000,000	$ 1,054,000,000
Loans outstanding under the credit agreement	0	0
Letters of credit outstanding under the credit agreement	$ 0	$ 2,000,000
Commercial Paper
Short-term Debt [Line Items]
Weighted average interest rate	1.30%	1.00%
CECONY
Short-term Debt [Line Items]
Commercial paper, outstanding	$ 147,000,000	$ 600,000,000
Letters of credit outstanding under the credit agreement	$ 0	$ 2,000,000
CECONY | Commercial Paper
Short-term Debt [Line Items]
Weighted average interest rate	1.30%	1.00%

Pension Benefits - Total Period

Pension Benefits - Total Periodic Benefit Costs (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	$ 66	$ 69	$ 197	$ 207
Interest cost on projected benefit obligation	148	149	444	447
Expected return on plan assets	(243)	(237)	(726)	(711)
Recognition of net actuarial loss	149	149	446	447
Recognition of prior service costs	(4)	1	(13)	3
TOTAL PERIODIC BENEFIT COST	116	131	348	393
Cost capitalized	(40)	(51)	(134)	(157)
Reconciliation to rate level	(14)	10	(28)	35
Cost charged to operating expenses	62	90	186	271
CECONY
Defined Benefit Plan Disclosure [Line Items]
Service cost – including administrative expenses	61	65	184	194
Interest cost on projected benefit obligation	139	140	416	419
Expected return on plan assets	(229)	(225)	(689)	(674)
Recognition of net actuarial loss	141	141	423	424
Recognition of prior service costs	(5)	0	(14)	1
TOTAL PERIODIC BENEFIT COST	107	121	320	364
Cost capitalized	(37)	(49)	(125)	(148)
Reconciliation to rate level	(16)	13	(32)	39
Cost charged to operating expenses	$ 54	$ 85	$ 163	$ 255

Pension Benefits - Additional I

Pension Benefits - Additional Information (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions	$ 450
Contributions	446
Pension Benefits | CECONY
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions	412
Contributions	409
External Trust Supplemental Plans | CECONY
Defined Benefit Plan Disclosure [Line Items]
Contributions	$ 14

Other Postretirement Benefits -

Other Postretirement Benefits - Total Periodic Postretirement Benefit Costs (Details) - Other Postretirement Benefits - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 5	$ 4	$ 15	$ 13
Interest cost on accumulated other postretirement benefit obligation	11	12	34	36
Expected return on plan assets	(17)	(19)	(52)	(58)
Recognition of net actuarial loss/(gain)	1	1	2	4
Recognition of prior service cost	(5)	(5)	(13)	(15)
TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST	(5)	(7)	(14)	(20)
Cost capitalized	2	2	6	5
Reconciliation to rate level	(1)	7	(3)	20
Cost charged to operating expenses	(4)	2	(11)	5
CECONY
Defined Benefit Plan Disclosure [Line Items]
Service cost	3	3	10	10
Interest cost on accumulated other postretirement benefit obligation	9	10	28	30
Expected return on plan assets	(15)	(17)	(45)	(50)
Recognition of net actuarial loss/(gain)	0	1	(2)	2
Recognition of prior service cost	(3)	(3)	(9)	(11)
TOTAL PERIODIC OTHER POSTRETIREMENT BENEFIT COST	(6)	(6)	(18)	(19)
Cost capitalized	2	2	7	5
Reconciliation to rate level	0	6	(1)	19
Cost charged to operating expenses	$ (4)	$ 2	$ (12)	$ 5

Other Postretirement Benefits49

Other Postretirement Benefits - Additional Information (Details) - Other Postretirement Benefits $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)
Defined Benefit Plan Disclosure [Line Items]
Contributions	$ 16
CECONY
Defined Benefit Plan Disclosure [Line Items]
Contributions	$ 8

Environmental Matters - Accrued

Environmental Matters - Accrued Liabilities and Regulatory Assets (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Site Contingency [Line Items]
Accrued liabilities	$ 745	$ 753
Regulatory assets	6,878	7,124
Manufactured gas plant sites
Site Contingency [Line Items]
Accrued liabilities	659	664
Other Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	86	89
Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	745	753
Regulatory assets	803	823
CECONY
Site Contingency [Line Items]
Accrued liabilities	648	655
Regulatory assets	6,348	6,563
CECONY | Manufactured gas plant sites
Site Contingency [Line Items]
Accrued liabilities	563	567
CECONY | Other Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	85	88
CECONY | Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	648	655
Regulatory assets	$ 690	$ 711

Environmental Matters - Environ

Environmental Matters - Environmental Remediation Costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Environmental Exit Cost [Line Items]
Remediation costs incurred	$ 4	$ 8	$ 18	$ 20
CECONY
Environmental Exit Cost [Line Items]
Remediation costs incurred	$ 3	$ 5	$ 13	$ 10

Environmental Matters - Additio

Environmental Matters - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Site Contingency [Line Items]
Insurance recoveries	$ 0	$ 1	$ 0	$ 1
CECONY
Site Contingency [Line Items]
Insurance recoveries	$ 0	$ 1	$ 0	$ 1
CECONY | Asbestos Proceedings
Site Contingency [Line Items]
Estimated undiscounted asbestos liability (years)			15 years
Superfund Sites | Manufactured Gas Plant Sites | Maximum
Site Contingency [Line Items]
Estimated aggregate undiscounted potential liability related environmental contaminants (up to)					$ 2,800
Superfund Sites | Manufactured Gas Plant Sites | Maximum | CECONY
Site Contingency [Line Items]
Estimated aggregate undiscounted potential liability related environmental contaminants (up to)					$ 2,600

Environmental Matters - Accru53

Environmental Matters - Accrued Liability for Asbestos Suits and Workers' Compensation Proceedings (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Site Contingency [Line Items]
Regulatory assets	$ 6,878	$ 7,124
Asbestos Suits
Site Contingency [Line Items]
Accrued liability	8	8
Regulatory assets	8	8
Workers’ Compensation
Site Contingency [Line Items]
Accrued liability	87	88
Regulatory assets	12	13
CECONY
Site Contingency [Line Items]
Regulatory assets	6,348	6,563
CECONY | Asbestos Suits
Site Contingency [Line Items]
Accrued liability	7	7
Regulatory assets	7	7
CECONY | Workers’ Compensation
Site Contingency [Line Items]
Accrued liability	83	83
Regulatory assets	$ 12	$ 13

Other Material Contingencies Ot

Other Material Contingencies Other Material Contingencies - Manhattan Explosion and Fire (Details) $ in Millions	Mar. 12, 2014buildingpeople	Feb. 28, 2017USD ($)	Sep. 30, 2017USD ($)lawsuit	Dec. 31, 2016USD ($)
Loss Contingencies [Line Items]
Accrued regulatory liability			$ 1,873	$ 1,905
Settlement of Gas Proceedings
Loss Contingencies [Line Items]
Accrued regulatory liability			$ 27	$ 27
Manhattan Explosion and Fire
Loss Contingencies [Line Items]
Number of buildings destroyed by fire | building	2
Number of people died in explosion and fire incident | people	8
Number of people injured in explosion and fire incident (more than) | people	50
Amount of costs that will not recover from customers		$ 126
Number of pending lawsuits | lawsuit			80
Manhattan Explosion and Fire | Settlement of Gas Proceedings
Loss Contingencies [Line Items]
Accrued regulatory liability			$ 27

Other Material Contingencies -

Other Material Contingencies - Total Guarantees (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 2,162	$ 2,370
Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	1,047
Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	700
Renewable electric production projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	287
Other
Guarantor Obligations [Line Items]
Total guarantees, by type and term	128
0 – 3 years
Guarantor Obligations [Line Items]
Total guarantees, by type and term	1,498
0 – 3 years | Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	643
0 – 3 years | Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	459
0 – 3 years | Renewable electric production projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	268
0 – 3 years | Other
Guarantor Obligations [Line Items]
Total guarantees, by type and term	128
4 – 10 years
Guarantor Obligations [Line Items]
Total guarantees, by type and term	434
4 – 10 years | Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	404
4 – 10 years | Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	30
4 – 10 years | Renewable electric production projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	0
4 – 10 years | Other
Guarantor Obligations [Line Items]
Total guarantees, by type and term	0
Greater than 10 years
Guarantor Obligations [Line Items]
Total guarantees, by type and term	230
Greater than 10 years | Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	0
Greater than 10 years | Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	211
Greater than 10 years | Renewable electric production projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	19
Greater than 10 years | Other
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 0

Other Material Contingencies 56

Other Material Contingencies Other Material Contingencies - Con Edison Transmission (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2014
Guarantor Obligations [Line Items]
Guarantee obligations maximum exposure	$ 2,162	$ 2,370
Payment Guarantee by CET Electric of Contributions to New York Transco LLC
Guarantor Obligations [Line Items]
Ownership interest, percentage			45.70%
Estimated project cost percentage	175.00%
Financial Guarantee in Behalf of CET Gas for Proposed Gas Transmission Project
Guarantor Obligations [Line Items]
Guarantee obligations maximum exposure	$ 25

Other Material Contingencies 57

Other Material Contingencies Other Material Contingencies - Other (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Guarantor Obligations [Line Items]
Guarantee obligations maximum exposure	$ 2,162	$ 2,370
Financial Guarantee for Indemnity Agreements for Surety Bonds
Guarantor Obligations [Line Items]
Guarantee obligations maximum exposure	70
Certain Obligations Under Agreement to Sell the Retail Electric Supply Business
Guarantor Obligations [Line Items]
Guarantee obligations maximum exposure	53
Financial Guarantee to Public Utility Commission of Texas
Guarantor Obligations [Line Items]
Guarantee obligations maximum exposure	$ 5

Income Tax (Details)

Income Tax (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Income Taxes Disclosure [Line Items]
Income tax expense	$ 270,000,000	$ 314,000,000	$ 599,000,000	$ 602,000,000
Effective tax rate	37.00%	39.00%	37.00%	37.00%
Deferred tax asset, net operating loss	$ 19,000,000		$ 19,000,000
Valuation allowance	0		0
Estimated liability for uncertain tax positions	41,000,000		41,000,000
Effective income tax rate reconciliation, uncertainty of taxes			35,000,000
Effective income tax rate reconciliation, uncertainty net of federal taxes			24,000,000
Unrecognized tax benefits that would have an impact on effective tax rate	21,000,000		21,000,000
Unrecognized tax benefits that would have an impact on effective tax rate, net of taxes	15,000,000		15,000,000
Total amount of unrecognized tax benefits, if recognized, that would reduce effective tax rate	25,000,000		25,000,000
Total amount of unrecognized tax benefits, if recognized, that would reduce effective tax rate, net of federal taxes	18,000,000		18,000,000
Interest expense for uncertain tax positions	0		0
Penalties for uncertain tax positions	0		0
Accrued interest on uncertain tax positions	0		0		$ 0
CECONY
Income Taxes Disclosure [Line Items]
Income tax expense	$ 242,000,000	$ 226,000,000	$ 551,000,000	$ 491,000,000
Effective tax rate	38.00%	37.00%	38.00%	36.00%
Estimated liability for uncertain tax positions	$ 21,000,000		$ 21,000,000
Effective income tax rate reconciliation, uncertainty of taxes			18,000,000
Effective income tax rate reconciliation, uncertainty net of federal taxes			13,000,000
Unrecognized tax benefits that would have an impact on effective tax rate	$ 4,000,000		$ 4,000,000

Financial Information by Busi59

Financial Information by Business Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Revenues	$ 3,211	$ 3,417	$ 9,072	$ 9,368
Depreciation and amortization	337	305	998	905
Operating income/(loss)	873	940	2,066	2,097
Clean Energy Businesses
Segment Reporting Information [Line Items]
Depreciation and amortization	19	11	54	30
Operating income/(loss)	29	125	63	184
Con Edison Transmission
Segment Reporting Information [Line Items]
Revenues			1	0
Depreciation and amortization			0	0
Operating income/(loss)	(2)	(1)	(6)	(1)
CECONY
Segment Reporting Information [Line Items]
Revenues	2,799	2,828	7,948	7,741
Depreciation and amortization	300	278	891	825
Operating income/(loss)	800	766	1,891	1,799
CECONY | Electric
Segment Reporting Information [Line Items]
Depreciation and amortization	232	217	690	645
Operating income/(loss)	855	841	1,477	1,487
CECONY | Gas
Segment Reporting Information [Line Items]
Depreciation and amortization	47	41	137	118
Operating income/(loss)	(12)	(28)	362	273
CECONY | Steam
Segment Reporting Information [Line Items]
Depreciation and amortization	21	20	64	62
Operating income/(loss)	(43)	(47)	52	39
O&R
Segment Reporting Information [Line Items]
Depreciation and amortization	18	17	53	50
Operating income/(loss)	45	48	116	114
O&R | Electric
Segment Reporting Information [Line Items]
Depreciation and amortization	13	12	38	37
Operating income/(loss)	56	55	83	86
O&R | Gas
Segment Reporting Information [Line Items]
Depreciation and amortization	5	5	15	13
Operating income/(loss)	(11)	(7)	33	28
Operating segment
Segment Reporting Information [Line Items]
Revenues	3,211	3,417	9,072	9,368
Operating segment | Clean Energy Businesses
Segment Reporting Information [Line Items]
Revenues	177	350	460	998
Operating segment | CECONY
Segment Reporting Information [Line Items]
Revenues	2,799	2,828	7,948	7,741
Operating segment | CECONY | Electric
Segment Reporting Information [Line Items]
Revenues	2,469	2,557	6,079	6,222
Operating segment | CECONY | Gas
Segment Reporting Information [Line Items]
Revenues	268	208	1,421	1,113
Operating segment | CECONY | Steam
Segment Reporting Information [Line Items]
Revenues	62	63	448	406
Operating segment | O&R
Segment Reporting Information [Line Items]
Revenues	234	240	667	630
Operating segment | O&R | Electric
Segment Reporting Information [Line Items]
Revenues	206	213	495	497
Operating segment | O&R | Gas
Segment Reporting Information [Line Items]
Revenues	28	27	172	133
Other
Segment Reporting Information [Line Items]
Revenues	0	(1)	(4)	(1)
Depreciation and amortization	0	(1)	0	0
Operating income/(loss)	1	2	2	1
Inter-segment
Segment Reporting Information [Line Items]
Revenues	0	2	0	(7)
Inter-segment | Clean Energy Businesses
Segment Reporting Information [Line Items]
Revenues	0	(2)	0	7
Inter-segment | CECONY
Segment Reporting Information [Line Items]
Revenues	(25)	(28)	(72)	(82)
Inter-segment | CECONY | Electric
Segment Reporting Information [Line Items]
Revenues	4	5	12	13
Inter-segment | CECONY | Gas
Segment Reporting Information [Line Items]
Revenues	2	1	5	4
Inter-segment | CECONY | Steam
Segment Reporting Information [Line Items]
Revenues	$ 19	$ 22	$ 55	$ 65

Derivative Instruments and He60

Derivative Instruments and Hedging Activities - Fair Values of Commodity Derivatives Including Offsetting of Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Net fair value derivative assets/(liabilities)
Gross Amounts of Recognized Assets/(Liabilities)	$ (143)	$ (99)
Gross Amounts Offset	3	6
Net Amounts of Assets/ (Liabilities)	(140)	(93)
Margin deposits	5	7
Interest Rate Swap
Fair value of derivative liabilities
Net Amounts of Assets/ (Liabilities)		(1)
CECONY
Net fair value derivative assets/(liabilities)
Gross Amounts of Recognized Assets/(Liabilities)	(131)	(95)
Gross Amounts Offset	3	9
Net Amounts of Assets/ (Liabilities)	(128)	(86)
Margin deposits	5	7
Fair Value of Derivative Liabilities, Current
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(141)	(138)
Gross Amounts Offset	71	61
Net Amounts of Assets/ (Liabilities)	(70)	(77)
Fair Value of Derivative Liabilities, Current | CECONY
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(116)	(111)
Gross Amounts Offset	57	45
Net Amounts of Assets/ (Liabilities)	(59)	(66)
Fair Value of Derivative Liabilities, Noncurrent
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(143)	(91)
Gross Amounts Offset	60	52
Net Amounts of Assets/ (Liabilities)	(83)	(39)
Fair Value of Derivative Liabilities, Noncurrent | CECONY
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(127)	(77)
Gross Amounts Offset	54	44
Net Amounts of Assets/ (Liabilities)	(73)	(33)
Fair Value of Derivative Liabilities
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(284)	(229)
Gross Amounts Offset	131	113
Net Amounts of Assets/ (Liabilities)	(153)	(116)
Fair Value of Derivative Liabilities | CECONY
Fair value of derivative liabilities
Gross Amounts of Recognized Assets/(Liabilities)	(243)	(188)
Gross Amounts Offset	111	89
Net Amounts of Assets/ (Liabilities)	(132)	(99)
Fair Value of Derivative Assets, Current
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	77	81
Gross Amounts Offset	(67)	(64)
Net Amounts of Assets/ (Liabilities)	10	17
Fair Value of Derivative Assets, Current | CECONY
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	55	52
Gross Amounts Offset	(53)	(45)
Net Amounts of Assets/ (Liabilities)	2	7
Fair Value of Derivative Assets, Noncurrent
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	64	49
Gross Amounts Offset	(61)	(43)
Net Amounts of Assets/ (Liabilities)	3	6
Fair Value of Derivative Assets, Noncurrent | CECONY
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	57	41
Gross Amounts Offset	(55)	(35)
Net Amounts of Assets/ (Liabilities)	2	6
Fair Value of Derivative Assets
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	141	130
Gross Amounts Offset	(128)	(107)
Net Amounts of Assets/ (Liabilities)	13	23
Fair Value of Derivative Assets | CECONY
Fair value of derivative assets
Gross Amounts of Recognized Assets/(Liabilities)	112	93
Gross Amounts Offset	(108)	(80)
Net Amounts of Assets/ (Liabilities)	$ 4	$ 13

Derivative Instruments and He61

Derivative Instruments and Hedging Activities - Realized and Unrealized Gains or Losses on Commodity Derivatives (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	$ (3)	$ (3)	$ (28)	$ 5
Total deferred gains/(losses)	(63)	(75)	(155)	(149)
Net deferred gains/(losses)	(66)	(78)	(183)	(144)
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	(42)	(77)	(150)	(163)
Purchased power expense
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	(37)	0	(106)
Unrealized gain/(loss) on derivatives		(23)		11
Gas purchased for resale
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	(47)	(38)	(161)	(72)
Non-utility revenue
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	5	(2)	11	15
Non-utility operating revenue
Pre-tax gains/(losses) recognized in income
Unrealized gain/(loss) on derivatives	6	(2)	2	(3)
Deferred Derivative Gains,Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(4)	(1)	(26)	6
Deferred Derivative Gains, Noncurrent
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	1	(2)	(2)	(1)
Deferred Derivative Losses, Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(11)	(19)	10	19
Recoverable Energy Costs, Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(40)	(39)	(125)	(163)
Deferred Derivative Losses, Noncurrent
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(12)	(17)	(40)	(5)
CECONY
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(2)	(3)	(24)	1
Total deferred gains/(losses)	(55)	(67)	(141)	(135)
Net deferred gains/(losses)	(57)	(70)	(165)	(134)
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	0	0	0
CECONY | Purchased power expense
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	0	0	0
CECONY | Gas purchased for resale
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	0	0	0
CECONY | Non-utility revenue
Pre-tax gains/(losses) recognized in income
Total pre-tax gains/(losses) recognized in income	0	0	0	0
CECONY | Deferred Derivative Gains,Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(3)	(3)	(22)	2
CECONY | Deferred Derivative Gains, Noncurrent
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	1	0	(2)	(1)
CECONY | Deferred Derivative Losses, Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(9)	(18)	11	16
CECONY | Recoverable Energy Costs, Current
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	(38)	(35)	(116)	(148)
CECONY | Deferred Derivative Losses, Noncurrent
Pre-tax gains/(losses) deferred in accordance with accounting rules for regulated operations:
Total deferred gains/(losses)	$ (8)	$ (14)	$ (36)	$ (3)

Derivative Instruments and He62

Derivative Instruments and Hedging Activities - Hedged Volume of Derivative Transactions (Details) gal in Thousands	Sep. 30, 2017galMMBTUMWMWh
Electric Energy
Derivatives, Fair Value [Line Items]
Notional amount | MWh	32,596,372
Capacity
Derivatives, Fair Value [Line Items]
Notional amount | MW	6,790
Natural Gas
Derivatives, Fair Value [Line Items]
Notional amount | MMBTU	166,913,644
Refined Fuels
Derivatives, Fair Value [Line Items]
Notional amount | gal	672
CECONY | Electric Energy
Derivatives, Fair Value [Line Items]
Notional amount | MWh	30,492,575
CECONY | Capacity
Derivatives, Fair Value [Line Items]
Notional amount | MW	3,000
CECONY | Natural Gas
Derivatives, Fair Value [Line Items]
Notional amount | MMBTU	158,500,000
CECONY | Refined Fuels
Derivatives, Fair Value [Line Items]
Notional amount | gal	672

Derivative Instruments and He63

Derivative Instruments and Hedging Activities - Additional Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Investment Holdings [Line Items]
Energy supply and hedging activities credit exposure total	$ 80
Makeup of net credit exposure with investment-grade counterparties	23
Makeup of net credit exposure non-investment grade/non-rated counterparties	23
Makeup of net credit exposure with commodity exchange brokers	15
Makeup of net credit exposure independent system operators	19
Interest Rate Swap
Investment Holdings [Line Items]
Derivative liabilities		$ 1
CECONY
Investment Holdings [Line Items]
Energy supply and hedging activities credit exposure total	8
Makeup of net credit exposure with investment-grade counterparties	1
Makeup of net credit exposure with commodity exchange brokers	7
Clean Energy Businesses | Coram | Interest Rate Swap
Investment Holdings [Line Items]
Derivative, fixed interest rate		2.0855%
Derivative liabilities	$ 0	$ 1

Derivative Instruments and He64

Derivative Instruments and Hedging Activities - Aggregate Fair Value of Companies' Derivative Instruments with Credit-Risk-Related Contingent Features (Details) $ in Millions	Sep. 30, 2017USD ($)
Derivatives, Fair Value [Line Items]
Aggregate fair value – net liabilities	$ 148
Collateral posted	61
Downgrade One Level from Current Ratings
Derivatives, Fair Value [Line Items]
Additional collateral	23
Downgrade to Below Investment Grade from Current Ratings
Derivatives, Fair Value [Line Items]
Additional collateral	101
Derivatives in net asset position additional collateral	13
Additional Collateral Required Due To Loss Of Unsecured Credit
Derivatives, Fair Value [Line Items]
Collateral posted	11
CECONY
Derivatives, Fair Value [Line Items]
Aggregate fair value – net liabilities	131
Collateral posted	56
CECONY | Downgrade One Level from Current Ratings
Derivatives, Fair Value [Line Items]
Additional collateral	22
CECONY | Downgrade to Below Investment Grade from Current Ratings
Derivatives, Fair Value [Line Items]
Additional collateral	$ 88

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Total		$ 1
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Netting Adjustment	$ (18)	(24)
Total assets	407	363
Derivative Liabilities, Netting Adjustment	(26)	(38)
Total liabilities	153	117
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	277	236
Total liabilities	2	4
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	146	144
Total liabilities	155	145
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	2	7
Total liabilities	22	6
Recurring | Commodity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Netting Adjustment	(18)	(24)
Net Amounts of Assets/ (Liabilities)	18	30
Derivative Liabilities, Netting Adjustment	(26)	(38)
Derivative Liabilities, Total	153	116
Recurring | Commodity | CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Netting Adjustment	(9)	(10)
Net Amounts of Assets/ (Liabilities)	9	20
Total assets	370	326
Derivative Liabilities, Netting Adjustment	(17)	(26)
Derivative Liabilities, Total	132	99
Recurring | Commodity | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Before Netting	6	14
Derivative Liabilities, Before Netting	2	4
Recurring | Commodity | Level 1 | CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Before Netting	5	10
Total assets	253	210
Derivative Liabilities, Before Netting	1	1
Recurring | Commodity | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Before Netting	28	33
Derivative Liabilities, Before Netting	155	144
Recurring | Commodity | Level 2 | CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Before Netting	12	19
Total assets	125	125
Derivative Liabilities, Before Netting	133	124
Recurring | Commodity | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Before Netting	2	7
Derivative Liabilities, Before Netting	22	6
Recurring | Commodity | Level 3 | CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Before Netting	1	1
Total assets	1	1
Derivative Liabilities, Before Netting	15	0
Recurring | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Netting Adjustment	0	0
Net Amounts of Assets/ (Liabilities)	389	333
Recurring | Other | CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Netting Adjustment	0	0
Net Amounts of Assets/ (Liabilities)	361	306
Recurring | Other | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Before Netting	271	222
Recurring | Other | Level 1 | CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Before Netting	248	200
Recurring | Other | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Before Netting	118	111
Recurring | Other | Level 2 | CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Before Netting	113	106
Recurring | Other | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Before Netting	0	0
Recurring | Other | Level 3 | CECONY
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Before Netting	0	0
Recurring | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Netting Adjustment	0	0
Derivative Liabilities, Total	0	1
Recurring | Interest Rate Swap | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Before Netting	0	0
Recurring | Interest Rate Swap | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Before Netting	0	1
Recurring | Interest Rate Swap | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liabilities, Before Netting	$ 0	$ 0

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Commodity Derivatives (Details) - Level 3 $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)$ / kW-month$ / MWh
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives | $	$ (20)
CECONY
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives | $	(14)
Electricity
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives | $	(21)
Electricity | CECONY
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives | $	$ (15)
Electricity | Forward Energy Prices | Minimum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per MWH) | $ / MWh	19
Electricity | Forward Energy Prices | Minimum | CECONY
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per MWH) | $ / MWh	20.50
Electricity | Forward Energy Prices | Maximum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per MWH) | $ / MWh	76.25
Electricity | Forward Energy Prices | Maximum | CECONY
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per MWH) | $ / MWh	76.25
Electricity | Forward Capacity Prices | Minimum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per kW-month) | $ / kW-month	1.26
Electricity | Forward Capacity Prices | Maximum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per kW-month) | $ / kW-month	9.47
Transmission Congestion Contracts/Financial Transmission Rights
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives | $	$ 1
Transmission Congestion Contracts/Financial Transmission Rights | Discount for Inter Zonal Forward Price Curves
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (percentage)	50.00%
Transmission Congestion Contracts/Financial Transmission Rights | Inter Zonal Forward Price Curves Adjusted for Historical Zonal Losses | Minimum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per MWH) | $ / MWh	0.50
Transmission Congestion Contracts/Financial Transmission Rights | Inter Zonal Forward Price Curves Adjusted for Historical Zonal Losses | Maximum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per MWH) | $ / MWh	6.75
Transmission Congestion Contracts
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives | $	$ 1
Transmission Congestion Contracts | Discount for Inter Zonal Forward Price Curves | CECONY
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (percentage)	50.00%

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation of Beginning and Ending Net Balances for Assets and Liabilities Measured at Level 3 Fair Value (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ (10)	$ 5	$ 1	$ 6
Included in earnings	7	(4)	8	(1)
Included in regulatory assets and liabilities	(13)	(5)	(21)	(11)
Purchases			1	2
Sales	0	4	0	4
Settlements	(4)	1	(9)	1
Ending balance	(20)	1	(20)	1
CECONY
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	(6)	2	1	8
Included in earnings	1	0	1	(1)
Included in regulatory assets and liabilities	(8)	(3)	(14)	(6)
Purchases			1	1
Sales	0	0	0	0
Settlements	(1)	1	(3)	(2)
Ending balance	$ (14)	$ 0	$ (14)	$ 0

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - Clean Energy Businesses - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Non-utility revenue
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Gain (loss) on Level 3 commodity derivative assets and liabilities	$ 0	$ 0	$ 0	$ 0
Change in fair value relating to Level 3 commodity derivative assets and liabilities	0	0	0	0
Purchased power expense
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Gain (loss) on Level 3 commodity derivative assets and liabilities	4	(5)	3	(6)
Change in fair value relating to Level 3 commodity derivative assets and liabilities	$ 4	$ (4)	$ 2	$ (2)

Variable Interest Entities (Det

Variable Interest Entities (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)MW
Variable Interest Entity, Not Primary Beneficiary | Copper Mountain Solar 3 | Nevada
Variable Interest Entity [Line Items]
Generating Capacity (MW AC) | MW	128
Power Purchase Agreement Term (in Years)	20 years
Maximum Exposure to Loss	$ 175
Variable Interest Entity, Not Primary Beneficiary | Mesquite Solar 1 | Arizona
Variable Interest Entity [Line Items]
Generating Capacity (MW AC) | MW	83
Power Purchase Agreement Term (in Years)	20 years
Maximum Exposure to Loss	$ 102
Variable Interest Entity, Not Primary Beneficiary | Copper Mountain Solar 2 | Nevada
Variable Interest Entity [Line Items]
Generating Capacity (MW AC) | MW	75
Power Purchase Agreement Term (in Years)	25 years
Maximum Exposure to Loss	$ 83
Variable Interest Entity, Not Primary Beneficiary | California Solar | California
Variable Interest Entity [Line Items]
Generating Capacity (MW AC) | MW	55
Power Purchase Agreement Term (in Years)	25 years
Maximum Exposure to Loss	$ 64
Variable Interest Entity, Not Primary Beneficiary | Broken Bow II | Nebraska
Variable Interest Entity [Line Items]
Generating Capacity (MW AC) | MW	38
Power Purchase Agreement Term (in Years)	25 years
Maximum Exposure to Loss	$ 44
Variable Interest Entity, Primary Beneficiary | Texas Solar 4
Variable Interest Entity [Line Items]
Percentage of variable interests	80.00%
Maximum exposure for consolidated investments	$ 7
Variable Interest Entity, Primary Beneficiary | Texas Solar 4 | Texas
Variable Interest Entity [Line Items]
Generating Capacity (MW AC) | MW	32
Power Purchase Agreement Term (in Years)	25 years
Maximum Exposure to Loss	$ 47
Variable Interest Entity, Not Primary Beneficiary, Aggregated Disclosure
Variable Interest Entity [Line Items]
Percentage of variable interests	50.00%

Dispositions (Details)

Dispositions (Details) - Con Edison Development $ in Millions	1 Months Ended	12 Months Ended
	May 31, 2017USD ($)	Dec. 31, 2018MW
Upton 2 | Scenario, Forecast
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Project generating capacity (in mw) | MW		180
Upton 2 | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration the project is sold	$ 11
Gain on sale of project	1
Gain on sale of project, net of tax	$ 0.7