Consolidated Statement Of Common Shareholders' Equity (USD $) In Millions, except Share data	CECONY [Member] Common Stock [Member]	CECONY [Member] Additional Paid- In Capital [Member]	CECONY [Member] Retained Earnings [Member]	CECONY [Member] Repurchased Con Edison Stock [Member]	CECONY [Member] Capital Stock Expense [Member]	CECONY [Member] Accumulated Other Comprehensive Income/(Loss) [Member]	CECONY [Member]	Common Stock [Member]	Additional Paid- In Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Capital Stock Expense [Member]	Accumulated Other Comprehensive Income/(Loss) [Member]	Total
BEGINNING BALANCE at Dec. 31, 2009	$ 589	$ 3,877	$ 5,909	$ (962)	$ (62)	$ (4)	$ 9,347	$ 30	$ 4,420	$ 6,904	$ (1,001)	$ (62)	$ (42)	$ 10,249
BEGINNING BALANCE (in shares) at Dec. 31, 2009	235,488,094							281,123,741			23,210,700
Net Income			246				246
Capital contribution from parent		12					12
Net income for common stock										226				226
Common stock dividends			(167)				(167)			(167)				(167)
Cumulative preferred dividends			(3)				(3)
Issuance of common shares-dividend reinvestment and employee stock plans (in shares)								647,731
Issuance of common shares-dividend reinvestment and employee stock plans									28					28
Other comprehensive income													3	3
ENDING BALANCE at Mar. 31, 2010	589	3,889	5,985	(962)	(62)	(4)	9,435	30	4,448	6,963	(1,001)	(62)	(39)	10,339
ENDING BALANCE (in shares) at Mar. 31, 2010	235,488,094							281,771,472			23,210,700
BEGINNING BALANCE at Dec. 31, 2009	589			(962)	(62)	(4)	9,347				(1,001)	(62)		10,249
BEGINNING BALANCE (in shares) at Dec. 31, 2009	235,488,094										23,210,700
Net Income							384							415
Net income for common stock							378							409
Cumulative preferred dividends							(6)							(6)
ENDING BALANCE at Jun. 30, 2010	589			(962)	(62)	(4)	9,414				(1,001)	(62)		10,380
ENDING BALANCE (in shares) at Jun. 30, 2010	235,488,094										23,210,700
BEGINNING BALANCE at Mar. 31, 2010	589	3,889	5,985	(962)	(62)	(4)	9,435	30	4,448	6,963	(1,001)	(62)	(39)	10,339
BEGINNING BALANCE (in shares) at Mar. 31, 2010	235,488,094							281,771,472			23,210,700
Net Income			138				138							186
Capital contribution from parent		12					12
Net income for common stock							135			183				183
Common stock dividends			(168)				(168)			(168)				(168)
Cumulative preferred dividends			(3)				(3)							(3)
Issuance of common shares-dividend reinvestment and employee stock plans (in shares)								555,964
Issuance of common shares-dividend reinvestment and employee stock plans									25					25
Other comprehensive income													1	1
ENDING BALANCE at Jun. 30, 2010	589	3,901	5,952	(962)	(62)	(4)	9,414	30	4,473	6,978	(1,001)	(62)	(38)	10,380
ENDING BALANCE (in shares) at Jun. 30, 2010	235,488,094							282,327,436			23,210,700
BEGINNING BALANCE at Dec. 31, 2010	589	4,234	6,132	(962)	(64)	(6)	9,923	31	4,915	7,220	(1,001)	(64)	(40)	11,061
BEGINNING BALANCE (in shares) at Dec. 31, 2010	235,488,094							291,616,334			23,210,700
Net Income			271				271
Net income for common stock										311				311
Common stock dividends			(170)				(170)			(175)				(175)
Cumulative preferred dividends			(3)				(3)
Issuance of common shares-dividend reinvestment and employee stock plans (in shares)								656,049
Issuance of common shares-dividend reinvestment and employee stock plans								1	30					31
Other comprehensive income													3	3
ENDING BALANCE at Mar. 31, 2011	589	4,234	6,230	(962)	(64)	(6)	10,021	32	4,945	7,356		(64)	(37)	11,231
ENDING BALANCE (in shares) at Mar. 31, 2011	235,488,094							292,272,383
BEGINNING BALANCE at Dec. 31, 2010	589	4,234		(962)	(64)	(6)	9,923				(1,001)	(64)		11,061
BEGINNING BALANCE (in shares) at Dec. 31, 2010	235,488,094										23,210,700
Net Income							432							483
Net income for common stock							426							477
Cumulative preferred dividends							(6)							(6)
ENDING BALANCE at Jun. 30, 2011	589	4,234		(962)	(64)	(6)	10,008					(64)		11,251
ENDING BALANCE (in shares) at Jun. 30, 2011	235,488,094
BEGINNING BALANCE at Mar. 31, 2011	589	4,234	6,230	(962)	(64)	(6)	10,021	32	4,945	7,356	(1,001)	(64)	(37)	11,231
BEGINNING BALANCE (in shares) at Mar. 31, 2011	235,488,094							292,272,383			23,210,700
Net Income			160				160							168
Net income for common stock							157			165				165
Common stock dividends			(170)				(170)			(175)				(175)
Cumulative preferred dividends			(3)				(3)							(3)
Issuance of common shares-dividend reinvestment and employee stock plans (in shares)								603,513			(182,942)
Issuance of common shares-dividend reinvestment and employee stock plans									32		5			37
Common stock repurchases											(9)			(9)
Common stock repurchases, shares											178,942
Other comprehensive income													2	2
ENDING BALANCE at Jun. 30, 2011	$ 589	$ 4,234	$ 6,217	$ (962)	$ (64)	$ (6)	$ 10,008	$ 32	$ 4,977	$ 7,346	$ (1,005)	$ (64)	$ (35)	$ 11,251
ENDING BALANCE (in shares) at Jun. 30, 2011	235,488,094							292,875,896			23,206,700