CONSOLIDATED STATEMENT OF EQUITY (UNAUDITED) - USD ($) shares in Millions, $ in Millions	Total	Subsidiaries	Common Stock	Common Stock Subsidiaries	Additional Paid-In Capital	Additional Paid-In Capital Subsidiaries	Retained Earnings	Retained Earnings Subsidiaries	Treasury Stock	Repurchased Con Edison Stock Subsidiaries	Capital Stock Expense	Capital Stock Expense Subsidiaries	Accumulated Other Comprehensive Income/(Loss)	Accumulated Other Comprehensive Income/(Loss) Subsidiaries	Non- controlling 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 (shares) at Dec. 31, 2019			333	235					23
Beginning Balance at Dec. 31, 2019	$ 18,213		$ 35		$ 8,054		$ 11,100		$ (1,038)		$ (110)		$ (19)		$ 191
Beginning Balance at Dec. 31, 2019		$ 14,147		$ 589		$ 5,669		$ 8,919		$ (962)		$ (62)		$ (6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	392						375								17
Net income		406						406
Common stock dividends	(255)	(246)					(255)	(246)
Issuance of common shares – public offering (shares)			1
Issuance of common shares - public offering	88				88
Issuance of common shares for stock plans	26				26
Capital contribution by parent		25				25
Other comprehensive income	5	1											5	1
Distributions to noncontrolling interest	(2)														(2)
Ending Balance (shares) at Mar. 31, 2020			334	235					23
Ending Balance at Mar. 31, 2020	18,467		$ 35		8,168		11,220		$ (1,038)		(110)		(14)		206
Ending Balance at Mar. 31, 2020		14,333		$ 589		5,694		9,079		(962)		(62)		(5)
Beginning Balance (shares) at Dec. 31, 2019			333	235					23
Beginning Balance at Dec. 31, 2019	18,213		$ 35		8,054		11,100		$ (1,038)		(110)		(19)		191
Beginning Balance at Dec. 31, 2019		14,147		$ 589		5,669		8,919		(962)		(62)		(6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,095
Net income	1,058	963
Other comprehensive income	7
Ending Balance (shares) at Sep. 30, 2020			334						23								235
Ending Balance at Sep. 30, 2020	18,711		$ 35		8,228		11,391		$ (1,038)		(110)				217
Ending Balance at Sep. 30, 2020														(4)		$ 14,575	$ 589	$ 5,869	$ 9,145	$ (962)	$ (62)	$ (4)
Beginning Balance (shares) at Mar. 31, 2020			334	235					23
Beginning Balance at Mar. 31, 2020	18,467		$ 35		8,168		11,220		$ (1,038)		(110)		(14)		206
Beginning Balance at Mar. 31, 2020		14,333		$ 589		5,694		9,079		(962)		(62)		(5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	202						190								12
Net income		152						152
Common stock dividends	(256)	(246)					(256)	(246)
Issuance of common shares for stock plans	30				30
Capital contribution by parent		25				25
Other comprehensive income		1												1
Distributions to noncontrolling interest	(2)														(2)
Ending Balance (shares) at Jun. 30, 2020			334	235					23
Ending Balance at Jun. 30, 2020	18,441		$ 35		8,198		11,154		$ (1,038)		(110)				216
Ending Balance at Jun. 30, 2020		14,265		$ 589		5,719		8,985		(962)		(62)		(4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	502						493								9
Net income	493	405														405			405
Common stock dividends	(256)						(256)									(245)			(245)
Issuance of common shares - public offering	0
Issuance of common shares for stock plans	30				30
Capital contribution by parent																150		150
Other comprehensive income	2															0						0
Distributions to noncontrolling interest	(8)														(8)
Ending Balance (shares) at Sep. 30, 2020			334						23								235
Ending Balance at Sep. 30, 2020	18,711		$ 35		8,228		11,391		$ (1,038)		(110)				217
Ending Balance at Sep. 30, 2020														(4)		$ 14,575	$ 589	$ 5,869	$ 9,145	$ (962)	$ (62)	$ (4)
Beginning Balance (shares) at Dec. 31, 2020			342	235					23
Beginning Balance at Dec. 31, 2020	19,065		$ 36		8,808		11,178		$ (1,038)		(112)		(25)		218
Beginning Balance at Dec. 31, 2020	18,847	14,849		$ 589		6,169		9,122		(962)		(62)		(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	420						419								1
Net income		465						465
Common stock dividends	(265)	(247)					(265)	(247)
Issuance of common shares for stock plans	28				28
Capital contribution by parent		125				125
Other comprehensive income	4												4
Distributions to noncontrolling interest	(3)														(3)
Net proceeds from sale of equity interest	33														33
Ending Balance (shares) at Mar. 31, 2021			342	235					23
Ending Balance at Mar. 31, 2021	19,282		$ 36		8,836		11,332		$ (1,038)		(112)		(21)		249
Ending Balance at Mar. 31, 2021		15,192		$ 589		6,294		9,340		(962)		(62)		(7)
Beginning Balance (shares) at Dec. 31, 2020			342	235					23
Beginning Balance at Dec. 31, 2020	19,065		$ 36		8,808		11,178		$ (1,038)		(112)		(25)		218
Beginning Balance at Dec. 31, 2020	18,847	14,849		$ 589		6,169		9,122		(962)		(62)		(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,007
Net income	1,122	1,011
Other comprehensive income	8
Ending Balance (shares) at Sep. 30, 2021			354	235					23
Ending Balance at Sep. 30, 2021	20,377		$ 37		9,683		11,495		$ (1,038)		(123)		(17)		340
Ending Balance at Sep. 30, 2021	20,037	16,220		$ 589		7,270		9,392		(962)		(62)		(7)
Beginning Balance (shares) at Mar. 31, 2021			342	235					23
Beginning Balance at Mar. 31, 2021	19,282		$ 36		8,836		11,332		$ (1,038)		(112)		(21)		249
Beginning Balance at Mar. 31, 2021		15,192		$ 589		6,294		9,340		(962)		(62)		(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	118						165								(47)
Net income		128						128
Common stock dividends	(266)	(247)					(266)	(247)
Issuance of common shares – public offering (shares)			11
Issuance of common shares - public offering	775		$ 1		785						(11)
Issuance of common shares for stock plans	34				34
Capital contribution by parent		851				851
Other comprehensive income	2												2
Distributions to noncontrolling interest	(4)														(4)
Net proceeds from sale of equity interest	112														112
Ending Balance (shares) at Jun. 30, 2021			353	235					23
Ending Balance at Jun. 30, 2021	20,053		$ 37		9,655		11,231		$ (1,038)		(123)		(19)		310
Ending Balance at Jun. 30, 2021		15,924		$ 589		7,145		9,221		(962)		(62)		(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	469						538								(69)
Net income	538	418						418
Common stock dividends	(274)	(247)					(274)	(247)
Issuance of common shares – public offering (shares)			1
Issuance of common shares - public offering	0
Issuance of common shares for stock plans	28				28
Capital contribution by parent		125				125
Other comprehensive income	2												2
Distributions to noncontrolling interest	(8)														(8)
Net proceeds from sale of equity interest	107														107
Ending Balance (shares) at Sep. 30, 2021			354	235					23
Ending Balance at Sep. 30, 2021	20,377		$ 37		$ 9,683		$ 11,495		$ (1,038)		$ (123)		$ (17)		$ 340
Ending Balance at Sep. 30, 2021	$ 20,037	$ 16,220		$ 589		$ 7,270		$ 9,392		$ (962)		$ (62)		$ (7)