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)	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, 2018		321			23
Beginning Balance (shares) at Dec. 31, 2018										235
Beginning Balance at Dec. 31, 2018	$ 16,839	$ 34	$ 7,117	$ 10,728	$ (1,038)	$ (99)	$ (16)	$ 113
Beginning Balance at Dec. 31, 2018									$ 12,910	$ 589	$ 4,769	$ 8,581	$ (962)	$ (62)	$ (5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	445			424				21
Net income									412			412
Common stock dividends	(237)			(237)					(228)			(228)
Issuance of common shares – public offering (shares)		6
Issuance of common shares - public offering	425		433			(8)
Issuance of common shares for stock plans	27		27
Capital contribution by parent									225		225
Other comprehensive income	4						4		0
Distributions to noncontrolling interest	(2)							(2)
Ending Balance (shares) at Mar. 31, 2019		327			23
Ending Balance (shares) at Mar. 31, 2019										235
Ending Balance at Mar. 31, 2019	17,501	$ 34	7,577	10,915	$ (1,038)	(107)	(12)	132
Ending Balance at Mar. 31, 2019									13,319	$ 589	4,994	8,765	(962)	(62)	(5)
Beginning Balance (shares) at Dec. 31, 2018		321			23
Beginning Balance (shares) at Dec. 31, 2018										235
Beginning Balance at Dec. 31, 2018	16,839	$ 34	7,117	10,728	$ (1,038)	(99)	(16)	113
Beginning Balance at Dec. 31, 2018									12,910	$ 589	4,769	8,581	(962)	(62)	(5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,127
Net income	1,048								978
Other comprehensive income	6								1
Ending Balance (shares) at Sep. 30, 2019		332			23
Ending Balance (shares) at Sep. 30, 2019										235
Ending Balance at Sep. 30, 2019	18,134	$ 35	8,031	11,051	$ (1,038)	(110)	(10)	175
Ending Balance at Sep. 30, 2019									14,079	$ 589	5,644	8,874	(962)	(62)	(4)
Beginning Balance (shares) at Mar. 31, 2019		327			23
Beginning Balance (shares) at Mar. 31, 2019										235
Beginning Balance at Mar. 31, 2019	17,501	$ 34	7,577	10,915	$ (1,038)	(107)	(12)	132
Beginning Balance at Mar. 31, 2019									13,319	$ 589	4,994	8,765	(962)	(62)	(5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	179			152				27
Net income									152			152
Common stock dividends	(242)			(242)					(228)			(228)
Issuance of common shares – public offering (shares)		5
Issuance of common shares - public offering	400	$ 1	402			(3)
Issuance of common shares for stock plans	29		29
Capital contribution by parent									625		625
Other comprehensive income	1						1		0
Distributions to noncontrolling interest	(3)							(3)
Ending Balance (shares) at Jun. 30, 2019		332			23
Ending Balance (shares) at Jun. 30, 2019										235
Ending Balance at Jun. 30, 2019	17,865	$ 35	8,008	10,825	$ (1,038)	(110)	(11)	156
Ending Balance at Jun. 30, 2019									13,868	$ 589	5,619	8,689	(962)	(62)	(5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	503			473				30
Net income	473								414			414
Common stock dividends	(247)			(247)					(229)			(229)
Issuance of common shares – public offering (shares)
Issuance of common shares - public offering	0
Issuance of common shares for stock plans	23		23
Capital contribution by parent									25		25
Other comprehensive income	1						1		1						1
Distributions to noncontrolling interest	(11)							(11)
Ending Balance (shares) at Sep. 30, 2019		332			23
Ending Balance (shares) at Sep. 30, 2019										235
Ending Balance at Sep. 30, 2019	18,134	$ 35	8,031	11,051	$ (1,038)	(110)	(10)	175
Ending Balance at Sep. 30, 2019									14,079	$ 589	5,644	8,874	(962)	(62)	(4)
Beginning Balance (shares) at Dec. 31, 2019		333			23
Beginning Balance (shares) at Dec. 31, 2019										235
Beginning Balance at Dec. 31, 2019	18,213	$ 35	8,054	11,100	$ (1,038)	(110)	(19)	191
Beginning Balance at Dec. 31, 2019	18,022								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)			(255)					(246)			(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						5		1						1
Distributions to noncontrolling interest	(2)							(2)
Ending Balance (shares) at Mar. 31, 2020		334			23
Ending Balance (shares) at Mar. 31, 2020										235
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			23
Beginning Balance (shares) at Dec. 31, 2019										235
Beginning Balance at Dec. 31, 2019	18,213	$ 35	8,054	11,100	$ (1,038)	(110)	(19)	191
Beginning Balance at Dec. 31, 2019	18,022								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								2
Ending Balance (shares) at Sep. 30, 2020		334			23
Ending Balance (shares) at Sep. 30, 2020										235
Ending Balance at Sep. 30, 2020	18,711	$ 35	8,228	11,391	$ (1,038)	(110)	(12)	217
Ending Balance at Sep. 30, 2020	18,494								14,575	$ 589	5,869	9,145	(962)	(62)	(4)
Beginning Balance (shares) at Mar. 31, 2020		334			23
Beginning Balance (shares) at Mar. 31, 2020										235
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)			(256)					(246)			(246)
Issuance of common shares – public offering (shares)
Issuance of common shares - public offering	0
Issuance of common shares for stock plans	30		30
Capital contribution by parent									25		25
Other comprehensive income	0								1						1
Distributions to noncontrolling interest	(2)							(2)
Ending Balance (shares) at Jun. 30, 2020		334			23
Ending Balance (shares) at Jun. 30, 2020										235
Ending Balance at Jun. 30, 2020	18,441	$ 35	8,198	11,154	$ (1,038)	(110)	(14)	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
Common stock dividends	(256)			(256)					(245)			(245)
Issuance of common shares – public offering (shares)
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						2		0						0
Distributions to noncontrolling interest	(8)							(8)
Ending Balance (shares) at Sep. 30, 2020		334			23
Ending Balance (shares) at Sep. 30, 2020										235
Ending Balance at Sep. 30, 2020	18,711	$ 35	$ 8,228	$ 11,391	$ (1,038)	$ (110)	$ (12)	$ 217
Ending Balance at Sep. 30, 2020	$ 18,494								$ 14,575	$ 589	$ 5,869	$ 9,145	$ (962)	$ (62)	$ (4)