Other Postretirement Benefits - Schedule of Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CHANGE IN PLAN ASSETS
Fair value of plan assets at beginning of year	$ 465
FAIR VALUE OF PLAN ASSETS AT END OF YEAR	525	$ 465
CECONY
CHANGE IN PLAN ASSETS
Fair value of plan assets at beginning of year	439
FAIR VALUE OF PLAN ASSETS AT END OF YEAR	499	439
Other Postretirement Benefits
CHANGE IN BENEFIT OBLIGATION
Projected benefit obligation at beginning of year	1,425	1,357	$ 1,114
Service cost	22	21	18
Interest cost on accumulated other postretirement benefit obligation	33	37	44
Amendments	0	0	(14)
Net actuarial loss/(gain)	(13)	74	264
Benefits paid and administrative expenses, net of subsidies	(117)	(117)	(110)
Participant contributions	48	53	41
PROJECTED BENEFIT OBLIGATION AT END OF YEAR	1,398	1,425	1,357
CHANGE IN PLAN ASSETS
Fair value of plan assets at beginning of year	1,115	1,026	885
Actual return on plan assets	92	142	198
Employer contributions	6	7	7
Employer group waiver plan subsidies	21	20	23
Participant contributions	48	53	40
Benefits paid	(132)	(133)	(127)
FAIR VALUE OF PLAN ASSETS AT END OF YEAR	1,150	1,115	1,026
FUNDED STATUS	(248)	(310)	(331)
Unrecognized net loss/(gain)	41	115	155
Unrecognized prior service costs	(13)	(16)	(19)
Other Postretirement Benefits | CECONY
CHANGE IN BENEFIT OBLIGATION
Projected benefit obligation at beginning of year	1,209	1,154	913
Service cost	16	16	13
Interest cost on accumulated other postretirement benefit obligation	28	31	36
Amendments	0	0	0
Net actuarial loss/(gain)	(3)	63	252
Benefits paid and administrative expenses, net of subsidies	(107)	(107)	(100)
Participant contributions	46	52	40
PROJECTED BENEFIT OBLIGATION AT END OF YEAR	1,189	1,209	1,154
CHANGE IN PLAN ASSETS
Fair value of plan assets at beginning of year	940	872	759
Actual return on plan assets	67	117	165
Employer contributions	3	4	6
Employer group waiver plan subsidies	19	19	22
Participant contributions	46	51	40
Benefits paid	(120)	(123)	(120)
FAIR VALUE OF PLAN ASSETS AT END OF YEAR	955	940	872
FUNDED STATUS	(234)	(269)	(282)
Unrecognized net loss/(gain)	67	114	149
Unrecognized prior service costs	$ 0	$ (1)	$ (3)