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, 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	311						311
Net Income		271						271
Common stock dividends	(175)	(170)					(175)	(170)
Issuance of common shares - dividend reinvestment and employee stock plans (In Shares)			656,049
Cumulative preferred dividends		(3)						(3)
Issuance of common shares - dividend reinvestment and employee stock plans	31		1		30
Other comprehensive income	3											3
BALANCE at Mar. 31, 2011	11,231	10,021	32	589	4,945	4,234	7,356	6,230		(64)	(64)	(37)	(6)	(962)
BALANCE (In Shares) at Mar. 31, 2011			292,272,383	235,488,094
BALANCE at Dec. 31, 2010	11,061	9,923		589		4,234			(1,001)	(64)	(64)		(6)	(962)
BALANCE (In Shares) at Dec. 31, 2010				235,488,094					23,210,700
Net income for common stock	860	779
Net Income	869	788
Cumulative preferred dividends	(9)
BALANCE at Sep. 30, 2011	11,454	10,192		589		4,234				(64)	(64)		(6)	(962)
BALANCE (In Shares) at Sep. 30, 2011				235,488,094
BALANCE at Mar. 31, 2011	11,231	10,021	32	589	4,945	4,234	7,356	6,230	(1,001)	(64)	(64)	(37)	(6)	(962)
BALANCE (In Shares) at Mar. 31, 2011			292,272,383	235,488,094					23,210,700
Net income for common stock	165						165
Net Income		160						160
Common stock dividends	(175)	(170)					(175)	(170)
Issuance of common shares - dividend reinvestment and employee stock plans (In Shares)			603,513						(182,942)
Cumulative preferred dividends		(3)						(3)
Issuance of common shares - dividend reinvestment and employee stock plans	37				32				5
Common stock repurchases	(9)								(9)
Common stock repurchases (In Shares)									178,942
Other comprehensive income	2											2
BALANCE at Jun. 30, 2011	11,251	10,008	32	589	4,977	4,234	7,346	6,217	(1,005)	(64)	(64)	(35)	(6)	(962)
BALANCE (In Shares) at Jun. 30, 2011			292,875,896	235,488,094					23,206,700
Net income for common stock	383	353					383
Net Income	386	356						356
Common stock dividends	(176)	(169)					(176)	(169)
Issuance of common shares - dividend reinvestment and employee stock plans (In Shares)			8,000						(554,356)
Cumulative preferred dividends	(3)	(3)						(3)
Issuance of common shares - dividend reinvestment and employee stock plans	25				6				19
Common stock repurchases	(31)								(31)
Common stock repurchases (In Shares)									546,356
Other comprehensive income	2											2
BALANCE at Sep. 30, 2011	11,454	10,192	32	589	4,983	4,234	7,553	6,401	(1,017)	(64)	(64)	(33)	(6)	(962)
BALANCE (In Shares) at Sep. 30, 2011			292,883,896	235,488,094					23,198,700
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						277
Net Income		276						276
Common stock dividends	(177)	(171)					(177)	(171)
Issuance of common shares - dividend reinvestment and employee stock plans (In Shares)			(7,225)						7,225
Cumulative preferred dividends		(3)						(3)
Issuance of common shares - dividend reinvestment and employee stock plans	(2)								(2)
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)		(962)
BALANCE (In Shares) at Mar. 31, 2012			292,881,296	235,488,094					23,201,300
BALANCE at Dec. 31, 2011	11,436	10,218		589	4,991	4,234							(8)	(962)
BALANCE (In Shares) at Dec. 31, 2011				235,488,094
Net income for common stock	931	824
Net Income	934	827
Cumulative preferred dividends	(3)
BALANCE at Sep. 30, 2012	11,842	10,532		589	4,991	4,234				(61)	(60)		(10)	(962)
BALANCE (In Shares) at Sep. 30, 2012				235,488,094
BALANCE at Mar. 31, 2012	11,545	10,324	32	589	4,991	4,234	7,668	6,531	(1,035)	(60)		(51)	(8)	(962)
BALANCE (In Shares) at Mar. 31, 2012			292,881,296	235,488,094					23,201,300
Net income for common stock	214						214
Net Income		163						163
Common stock dividends	(178)	(171)					(178)	(171)
Issuance of common shares - dividend reinvestment and employee stock plans (In Shares)			1,700						(1,700)
Issuance of common shares - dividend reinvestment and employee stock plans	(1)									(1)
Other comprehensive income	(1)	(2)										(1)	(2)
BALANCE at Jun. 30, 2012	11,579	10,314	32	589	4,991	4,234	7,704	6,523	(1,035)	(61)	(60)	(52)	(10)	(962)
BALANCE (In Shares) at Jun. 30, 2012			292,882,996	235,488,094					23,199,600
Net income for common stock	440	389					440
Net Income	440	389						389
Common stock dividends	(177)	(171)					(177)	(171)
Issuance of common shares - dividend reinvestment and employee stock plans (In Shares)			(11,100)						11,100
Issuance of common shares - dividend reinvestment and employee stock plans	(2)								(2)
Other comprehensive income	2											2
BALANCE at Sep. 30, 2012	$ 11,842	$ 10,532	$ 32	$ 589	$ 4,991	$ 4,234	$ 7,967	$ 6,741	$ (1,037)	$ (61)	$ (60)	$ (50)	$ (10)	$ (962)
BALANCE (In Shares) at Sep. 30, 2012			292,871,896	235,488,094					23,210,700