CONSOLIDATED STATEMENT OF COMMON SHAREHOLDERS EQUITY (USD $) In Millions, except Share data	Total	CECONY [Member]	Common Stock [Member]	Common Stock [Member] CECONY [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] CECONY [Member]	Retained Earnings [Member]	Retained Earnings [Member] CECONY [Member]	Treasury Stock [Member]	Capital Stock Expense [Member]	Capital Stock Expense [Member] CECONY [Member]	Accumulated Other Comprehensive Income/(Loss) [Member]	Accumulated Other Comprehensive Income/(Loss) [Member] CECONY [Member]	Repurchased Con Edison Stock [Member] CECONY [Member]
BALANCE at Dec. 31, 2011	$ 11,436	$ 10,218	$ 32	$ 589	$ 4,991	$ 4,234	$ 7,568	$ 6,429	$ (1,033)	$ (64)	$ (64)	$ (58)	$ (8)	$ (962)
BALANCE (In Shares) at Dec. 31, 2011			292,888,521	235,488,094					23,194,075
Net income for common stock	277	273					277
NET INCOME	280	276						276
Common stock dividend	(177)	(171)					(177)	(171)
Issuance of common shares for stock plans, net of repurchases	(2)								(2)
Cumulative preferred dividends	(3)	(3)						(3)
Issuance of common shares for stock plans, net of repurchases (In Shares)			(7,225)						7,225
Preferred stock redemption	4	4								4	4
Other comprehensive income	7											7
BALANCE at Mar. 31, 2012	11,545	10,324	32	589	4,991	4,234	7,668	6,531	(1,035)	(60)	(60)	(51)	(8)	(962)
BALANCE (In Shares) at Mar. 31, 2012			292,881,296	235,488,094					23,201,300
BALANCE at Dec. 31, 2012	11,869	10,552	32	589	4,991	4,234	7,997	6,761	(1,037)	(61)	(61)	(53)	(9)	(962)
BALANCE (In Shares) at Dec. 31, 2012			292,871,896	235,488,094					23,210,700
Net income for common stock	192	277					192
NET INCOME	192	277						277
Common stock dividend	(180)	(182)					(180)	(182)
Issuance of common shares for stock plans, net of repurchases	5				(2)				7
Issuance of common shares for stock plans, net of repurchases (In Shares)			95,468						(95,468)
Other comprehensive income	3											3
BALANCE at Mar. 31, 2013	$ 11,889	$ 10,647	$ 32	$ 589	$ 4,989	$ 4,234	$ 8,009	$ 6,856	$ (1,030)	$ (61)	$ (61)	$ (50)	$ (9)	$ (962)
BALANCE (In Shares) at Mar. 31, 2013			292,967,364	235,488,094					23,115,232