Consolidated Statement of Equity/Shareholder's Equity (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	Capital Stock Expense	Accumulated Other Comprehensive Income/(Loss)	Noncontrolling Interest	CECONY	CECONY Common Stock	CECONY Additional Paid-In Capital	CECONY Retained Earnings	CECONY Repurchased Con Edison Stock	CECONY Capital Stock Expense	CECONY Accumulated Other Comprehensive Income/(Loss)
Beginning Balance (in shares) at Dec. 31, 2015		293			23					235
Beginning Balance at Dec. 31, 2015	$ 13,061	$ 32	$ 5,030	$ 9,123	$ (1,038)	$ (61)	$ (34)	$ 9							$ (9)
Beginning Balance at Dec. 31, 2015									$ 11,415	$ 589	$ 4,247	$ 7,611	$ (962)	$ (61)	(9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	310			310					310			310
Common stock dividends	(197)			(197)					(186)			(186)
Issuance of common shares for stock plans (in shares)		1
Issuance of common shares for stock plans	28		28
Capital contribution by parent									23		23
Other comprehensive income (loss)	0								0						0
Noncontrolling interest	(1)							(1)
Ending Balance (in shares) at Mar. 31, 2016		294			23					235
Ending Balance at Mar. 31, 2016									11,562	$ 589	4,270	7,735	(962)	(61)	(9)
Ending Balance at Mar. 31, 2016	13,201	$ 32	5,058	9,236	$ (1,038)	(61)	(34)	8							(9)
Beginning Balance (in shares) at Dec. 31, 2015		293			23					235
Beginning Balance at Dec. 31, 2015	13,061	$ 32	5,030	9,123	$ (1,038)	(61)	(34)	9							(9)
Beginning Balance at Dec. 31, 2015									11,415	$ 589	4,247	7,611	(962)	(61)	(9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	542								472
Other comprehensive income (loss)	1								1
Ending Balance (in shares) at Jun. 30, 2016		304			23					235
Ending Balance at Jun. 30, 2016									11,566	$ 589	4,298	7,710	(962)	(61)	(8)
Ending Balance at Jun. 30, 2016	13,958	$ 33	5,807	9,264	$ (1,038)	(83)	(33)	8							(8)
Beginning Balance (in shares) at Mar. 31, 2016		294			23					235
Beginning Balance at Mar. 31, 2016	13,201	$ 32	5,058	9,236	$ (1,038)	(61)	(34)	8							(9)
Beginning Balance at Mar. 31, 2016									11,562	$ 589	4,270	7,735	(962)	(61)	(9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	232			232					161			161
Common stock dividends	(204)			(204)					(186)			(186)
Issuance of common shares for stock plans (in shares)
Issuance of common shares for stock plans	26		26
Issuance of common shares - public offering (in shares)		10
Issuance of common shares - public offering	702	$ 1	723			(22)
Capital contribution by parent									28		28
Other comprehensive income (loss)	1						1		1						1
Noncontrolling interest	0
Ending Balance (in shares) at Jun. 30, 2016		304			23					235
Ending Balance at Jun. 30, 2016									11,566	$ 589	4,298	7,710	(962)	(61)	(8)
Ending Balance at Jun. 30, 2016	13,958	$ 33	5,807	9,264	$ (1,038)	(83)	(33)	8							(8)
Beginning Balance (in shares) at Dec. 31, 2016		305			23					235
Beginning Balance at Dec. 31, 2016	14,306	$ 33	5,854	9,559	$ (1,038)	(83)	(27)	8							(7)
Beginning Balance at Dec. 31, 2016	14,298								11,829	$ 589	4,347	7,923	(962)	(61)	(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	388			388					339			339
Common stock dividends	(211)			(211)					(199)			(199)
Issuance of common shares for stock plans	24		24
Capital contribution by parent									22		22
Other comprehensive income (loss)	(1)						(1)		0
Noncontrolling interest	0
Ending Balance (in shares) at Mar. 31, 2017		305			23					235
Ending Balance at Mar. 31, 2017									11,991	$ 589	4,369	8,063	(962)	(61)	(7)
Ending Balance at Mar. 31, 2017	14,506	$ 33	5,878	9,736	$ (1,038)	(83)	(28)	8							(7)
Beginning Balance (in shares) at Dec. 31, 2016		305			23					235
Beginning Balance at Dec. 31, 2016	14,306	$ 33	5,854	9,559	$ (1,038)	(83)	(27)	8							(7)
Beginning Balance at Dec. 31, 2016	14,298								11,829	$ 589	4,347	7,923	(962)	(61)	(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	563								482
Other comprehensive income (loss)	0								0
Ending Balance (in shares) at Jun. 30, 2017		306			23					235
Ending Balance at Jun. 30, 2017	14,490								11,958	$ 589	4,392	8,007	(962)	(61)	(7)
Ending Balance at Jun. 30, 2017	14,498	$ 33	5,904	9,701	$ (1,038)	(83)	(27)	8							(7)
Beginning Balance (in shares) at Mar. 31, 2017		305			23					235
Beginning Balance at Mar. 31, 2017	14,506	$ 33	$ 5,878	9,736	$ (1,038)	(83)	(28)	8							(7)
Beginning Balance at Mar. 31, 2017									11,991	$ 589	4,369	8,063	(962)	(61)	(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	175			175					143			143
Common stock dividends	(210)			(210)					(199)			(199)
Issuance of common shares for stock plans (in shares)			1
Issuance of common shares for stock plans	26		$ 26
Capital contribution by parent									23		23
Other comprehensive income (loss)	1						1		0
Noncontrolling interest	0
Ending Balance (in shares) at Jun. 30, 2017		306			23					235
Ending Balance at Jun. 30, 2017	14,490								$ 11,958	$ 589	$ 4,392	$ 8,007	$ (962)	$ (61)	(7)
Ending Balance at Jun. 30, 2017	$ 14,498	$ 33	$ 5,904	$ 9,701	$ (1,038)	$ (83)	$ (27)	$ 8							$ (7)