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, 2009	$ 10,249	$ 9,347	$ 30	$ 589	$ 4,420	$ 3,877	$ 6,904	$ 5,909	$ (1,001)	$ (62)	$ (62)	$ (42)	$ (4)	$ (962)
BALANCE (In Shares) at Dec. 31, 2009			281,123,741	235,488,094					23,210,700
Net income for common stock	992	893					992
Net Income	1,003	904						904
Common stock dividend	(676)	(670)					(676)	(670)
Issuance of common shares - public offering	306		1		307					(2)
Capital contribution by parent		355				357					(2)
Issuance of common shares - public offering (In Shares)			6,300,000
Cumulative preferred dividends	(11)	(11)						(11)
Issuance of common shares - dividend reinvestment and employee stock plans	188				188
Issuance of common shares - dividend reinvestment and employee stock plans (In Shares)			4,192,593
Other comprehensive income	2	(2)										2	(2)
BALANCE at Dec. 31, 2010	11,061	9,923	31	589	4,915	4,234	7,220	6,132	(1,001)	(64)	(64)	(40)	(6)	(962)
BALANCE (In Shares) at Dec. 31, 2010			291,616,334	235,488,094					23,210,700
Net income for common stock	1,051	978					1,051
Net Income	1,062	989						989
Common stock dividend	(703)	(681)					(703)	(681)
Cumulative preferred dividends	(11)	(11)						(11)
Issuance of common shares - dividend reinvestment and employee stock plans	132		1		76				55
Issuance of common shares - dividend reinvestment and employee stock plans (In Shares)			1,272,187						(1,538,166)
Common stock repurchases	(87)								(87)
Common stock repurchases(in Shares)									1,521,541
Other comprehensive income	(18)	(2)										(18)	(2)
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	292,888,521	235,488,094					23,194,075
Net income for common stock	1,138	1,014					1,138
Net Income	1,141	1,017						1,017
Common stock dividend	(709)	(682)					(709)	(682)
Cumulative preferred dividends	(3)	(3)						(3)
Issuance of common shares - dividend reinvestment and employee stock plans	(1)								(4)	3
Preferred stock redemption		3									3
Issuance of common shares - dividend reinvestment and employee stock plans (In Shares)			(16,625)						16,625
Other comprehensive income	5	(1)										5	(1)
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	292,871,896	235,488,094					23,210,700