Financial Information By Business Segment (Financial Data For The Business Segments) (Details) (USD $) In Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010
Operating revenues	$ 2,993		$ 3,017		$ 6,342		$ 6,478
Depreciation and amortization	219		211		437		415
Operating income	398		429		1,024		921
CECONY - Electric [Member]
Operating revenues	2,013		2,104		3,734		3,832
Inter-segment revenues	3		2		6		6
Depreciation and amortization	162		156		324		307
Operating income	350		319		566		514
CECONY - Gas [Member]
Operating revenues	296		239		959		922
Inter-segment revenues	1		1		2		2
Depreciation and amortization	27		25		54		50
Operating income	31		44		237		259
CECONY - Steam [Member]
Operating revenues	107		89		432		396
Inter-segment revenues	20		18		40		36
Depreciation and amortization	16		15		32		31
Operating income	(11)		(29)		114		73
O&R - Electric [Member]
Operating revenues	141		153		289		314
Depreciation and amortization	8		8		17		16
Operating income	14		15		25		22
O&R - Gas [Member]
Operating revenues	37		35		130		125
Depreciation and amortization	4		3		7		6
Operating income	1		(1)		28		21
Competitive Energy Businesses [Member]
Operating revenues	406		406		814		906
Inter-segment revenues	2		2		5		4
Depreciation and amortization	2		4		3		5
Operating income	14		81		58		33
Other Revenues and Eliminations in Segment Information [Member]
Operating revenues	(7)	[1]	(9)	[1]	(16)	[1]	(17)	[1]
Inter-segment revenues	(2)	[1]	(2)	[1]	(5)	[1]	(4)	[1]
Operating income	(1)	[1]			(4)	[1]	(1)	[1]
CECONY [Member]
Operating revenues	2,416		2,432		5,125		5,150
Depreciation and amortization	205		196		410		388
Operating income	370		334		917		846
Consolidation Adjustments [Member]
Inter-segment revenues	(24)		(21)		(48)		(44)
O&R [Member]
Operating revenues	178		188		419		439
Depreciation and amortization	12		11		24		22
Operating income	$ 15		$ 14		$ 53		$ 43

[1] Parent company expenses, primarily interest, and consolidation adjustments. Other does not represent a business segment.