Schedule I - Condensed Financial Information - Condensed Statement of Cash Flows (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Supplemental Cash Flow Information [Line Items]
Net Income	$ 1,062	$ 1,138	$ 1,051
Common stock dividends	721	709	693
Change in Assets:
Special deposits	(257)	(13)	(4)
Other - net	34	40	55
NET CASH FLOWS FROM OPERATING ACTIVITIES	2,552	2,599	3,137
INVESTING ACTIVITIES
NET CASH FLOWS USED IN INVESTING ACTIVITIES	(2,659)	(2,523)	(2,150)
FINANCING ACTIVITIES
Net proceeds of short-term debt	912	539
Retirement of long-term debt	709	305	4
Common stock dividends	721	709	693
NET CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES	387	(330)	(677)
Net Change for the Period	280	(254)	310
BALANCE AT BEGINNING OF PERIOD	394	648	338
BALANCE AT END OF PERIOD	674	394	648
Parent Company [Member]
Supplemental Cash Flow Information [Line Items]
Net Income	1,062	1,138	1,051
Common stock dividends	(721)	(709)	(693)
Equity in earnings of subsidiaries	(1,062)	(1,154)	(1,064)
Change in Assets:
Special deposits	(264)
Other - net	166	(208)	(67)
NET CASH FLOWS FROM OPERATING ACTIVITIES	680	503	646
INVESTING ACTIVITIES
Contributions to subsidiaries		(100)
NET CASH FLOWS USED IN INVESTING ACTIVITIES		(100)
FINANCING ACTIVITIES
Net proceeds of short-term debt	58	115
Retirement of long-term debt	(1)	(1)	(1)
Issuance of common shares for stock plans, net of repurchases	(8)	(9)	31
Common stock dividends	(721)	(709)	(693)
NET CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES	(672)	(604)	(663)
Net Change for the Period	8	(201)	(17)
BALANCE AT BEGINNING OF PERIOD	4	205	222
BALANCE AT END OF PERIOD	12	4	205
CECONY [Member]
Supplemental Cash Flow Information [Line Items]
Net Income	1,020	1,014	978
Change in Assets:
Other - net	(88)	(40)	170
NET CASH FLOWS FROM OPERATING ACTIVITIES	2,643	2,346	2,933
INVESTING ACTIVITIES
NET CASH FLOWS USED IN INVESTING ACTIVITIES	(2,417)	(1,958)	(1,947)
FINANCING ACTIVITIES
Retirement of long-term debt	700	300
NET CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES	54	(407)	(692)
Net Change for the Period	280	(19)	294
BALANCE AT BEGINNING OF PERIOD	353	372	78
BALANCE AT END OF PERIOD	633	353	372
CECONY [Member] | Parent Company [Member]
Supplemental Cash Flow Information [Line Items]
Common stock dividends	728	682	681
FINANCING ACTIVITIES
Common stock dividends	728	682	681
O&R [Member] | Parent Company [Member]
Supplemental Cash Flow Information [Line Items]
Common stock dividends	38	34	33
FINANCING ACTIVITIES
Common stock dividends	38	34	33
Competitive Energy Businesses [Member] | Parent Company [Member]
Supplemental Cash Flow Information [Line Items]
Common stock dividends	12	11	12
FINANCING ACTIVITIES
Common stock dividends	$ 12	$ 11	$ 12