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, 2017		310			23
Beginning Balance (shares) at Dec. 31, 2017										235
Beginning Balance at Dec. 31, 2017	$ 15,425	$ 34	$ 6,298	$ 10,235	$ (1,038)	$ (85)	$ (26)	$ 7
Beginning Balance at Dec. 31, 2017									$ 12,439	$ 589	$ 4,649	$ 8,231	$ (962)	$ (62)	$ (6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	428			428
Net income									389			389
Common stock dividends	(221)			(221)					(211)			(211)
Issuance of common shares for stock plans (shares)		1
Issuance of common shares for stock plans	25		25
Capital contribution by parent									45		45
Other comprehensive income	4						4		0
Distributions to noncontrolling interest	0
Ending Balance (shares) at Mar. 31, 2018		311			23
Ending Balance (shares) at Mar. 31, 2018										235
Ending Balance at Mar. 31, 2018	15,661	$ 34	6,323	10,442	$ (1,038)	(85)	(22)	7
Ending Balance at Mar. 31, 2018									12,662	$ 589	4,694	8,409	(962)	(62)	(6)
Beginning Balance (shares) at Dec. 31, 2017		310			23
Beginning Balance (shares) at Dec. 31, 2017										235
Beginning Balance at Dec. 31, 2017	15,425	$ 34	6,298	10,235	$ (1,038)	(85)	(26)	7
Beginning Balance at Dec. 31, 2017									12,439	$ 589	4,649	8,231	(962)	(62)	(6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,051
Net income	1,051								969
Other comprehensive income	8								1
Ending Balance (shares) at Sep. 30, 2018		311			23
Ending Balance (shares) at Sep. 30, 2018										235
Ending Balance at Sep. 30, 2018	15,898	$ 34	6,375	10,619	$ (1,038)	(85)	(18)	11
Ending Balance at Sep. 30, 2018									12,869	$ 589	4,744	8,565	(962)	(62)	(5)
Beginning Balance (shares) at Mar. 31, 2018		311			23
Beginning Balance (shares) at Mar. 31, 2018										235
Beginning Balance at Mar. 31, 2018	15,661	$ 34	6,323	10,442	$ (1,038)	(85)	(22)	7
Beginning Balance at Mar. 31, 2018									12,662	$ 589	4,694	8,409	(962)	(62)	(6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	188			188
Net income									149			149
Common stock dividends	(223)			(223)					(212)			(212)
Issuance of common shares for stock plans (shares)
Issuance of common shares for stock plans	27		27
Capital contribution by parent									25		25
Other comprehensive income	2						2		1						1
Distributions to noncontrolling interest	0
Ending Balance (shares) at Jun. 30, 2018		311			23
Ending Balance (shares) at Jun. 30, 2018										235
Ending Balance at Jun. 30, 2018	15,655	$ 34	6,350	10,407	$ (1,038)	(85)	(20)	7
Ending Balance at Jun. 30, 2018									12,625	$ 589	4,719	8,346	(962)	(62)	(5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	435			435
Net income	435								431			431
Common stock dividends	(223)			(223)					(212)			(212)
Issuance of common shares for stock plans (shares)
Issuance of common shares for stock plans	25		25
Capital contribution by parent									25		25
Other comprehensive income	2						2		0
Noncontrolling interest	4							4
Ending Balance (shares) at Sep. 30, 2018		311			23
Ending Balance (shares) at Sep. 30, 2018										235
Ending Balance at Sep. 30, 2018	15,898	$ 34	6,375	10,619	$ (1,038)	(85)	(18)	11
Ending Balance at Sep. 30, 2018									12,869	$ 589	4,744	8,565	(962)	(62)	(5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	331			331
Net income									227			227
Common stock dividends	(222)			(222)					(211)			(211)
Issuance of common shares – public offering (shares)		10
Issuance of common shares – public offering	705		719			(14)
Issuance of common shares for stock plans (shares)
Issuance of common shares for stock plans	23		23
Capital contribution by parent									25		25
Other comprehensive income	2						2		0
Noncontrolling interest	102							102
Ending Balance (shares) at Dec. 31, 2018		321			23
Ending Balance (shares) at Dec. 31, 2018										235
Ending Balance at Dec. 31, 2018	16,839	$ 34	7,117	10,728	$ (1,038)	(99)	(16)	113
Ending Balance at Dec. 31, 2018	16,726								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	16,726								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	17,959								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 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	$ 17,959								$ 14,079	$ 589	$ 5,644	$ 8,874	$ (962)	$ (62)	$ (4)