Other Postretirement Benefits - Schedule of Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CHANGE IN PLAN ASSETS
Fair value of plan assets at beginning of year	$ 459
FAIR VALUE OF PLAN ASSETS AT END OF YEAR	524	$ 459
CECONY
CHANGE IN PLAN ASSETS
Fair value of plan assets at beginning of year	439
FAIR VALUE OF PLAN ASSETS AT END OF YEAR	502	439
Other Postretirement Benefits
CHANGE IN BENEFIT OBLIGATION
Projected benefit obligation at beginning of year	1,058	1,398	$ 1,425
Service cost	14	18	22
Interest cost on accumulated other postretirement benefit obligation	57	35	33
Net actuarial gain	(93)	(311)	(13)
Benefits paid and administrative expenses, net of subsidies	(128)	(130)	(117)
Participant contributions	55	48	48
PROJECTED BENEFIT OBLIGATION AT END OF YEAR	963	1,058	1,398
CHANGE IN PLAN ASSETS
Fair value of plan assets at beginning of year	860	1,150	1,115
Actual return on plan assets	116	(225)	92
Employer contributions	22	13	6
Employer group waiver plan subsidies	56	55	21
Participant contributions	55	48	48
Benefits paid	(180)	(181)	(132)
FAIR VALUE OF PLAN ASSETS AT END OF YEAR	929	860	1,150
FUNDED STATUS	(34)	(198)	(248)
Unrecognized net loss/(gain)	(90)	37	41
Unrecognized prior service costs	(10)	(12)	(13)
Other Postretirement Benefits | CECONY
CHANGE IN BENEFIT OBLIGATION
Projected benefit obligation at beginning of year	921	1,189	1,209
Service cost	12	15	16
Interest cost on accumulated other postretirement benefit obligation	49	30	28
Net actuarial gain	(94)	(239)	(3)
Benefits paid and administrative expenses, net of subsidies	(118)	(121)	(107)
Participant contributions	55	47	46
PROJECTED BENEFIT OBLIGATION AT END OF YEAR	825	921	1,189
CHANGE IN PLAN ASSETS
Fair value of plan assets at beginning of year	708	955	940
Actual return on plan assets	84	(187)	67
Employer contributions	17	10	3
Employer group waiver plan subsidies	52	50	19
Participant contributions	55	47	46
Benefits paid	(166)	(167)	(120)
FAIR VALUE OF PLAN ASSETS AT END OF YEAR	750	708	955
FUNDED STATUS	(75)	(213)	(234)
Unrecognized net loss/(gain)	(41)	78	67
Unrecognized prior service costs	$ 0	$ 0	$ 0