Income Tax - Income Tax Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
STATUTORY TAX RATE
Federal	$ 62	$ 40	$ 279	$ 230
Federal	21.00%	21.00%	21.00%	21.00%
Changes in computed taxes resulting from:
State income taxes, net of federal income taxes (a)	$ 13	$ 5	$ 69	$ 52
MTA Surcredit amortization, net of federal taxes	7	2	21	2
Tax Credits	(5)	(6)	(9)	(13)
Changes in unrecognized tax benefits	1	1	2	1
Amortization of excess deferred federal income taxes (b)	(11)	(51)	(22)	(101)
Allowance for uncollectible accounts, net of COVID-19 assistance	(9)	1	(21)	(4)
Cost of removal	9	8	19	20
Other plant-related items	0	(5)	0	(5)
Other	3	1	4	4
Effective tax rate	$ 50	$ (10)	$ 292	$ 174
Changes in computed taxes resulting from:
State income taxes, net of federal income taxes (a)	4.60%	2.40%	5.20%	4.70%
MTA Surcredit amortization, net of federal taxes	0.025	0.010	0.016	0.002
Tax Credits	(1.80%)	(3.40%)	(0.60%)	(1.10%)
Changes in unrecognized tax benefits	0.30%	0.30%	0.10%	0.10%
Amortization of excess deferred federal income taxes (b)	(3.70%)	(26.70%)	(1.70%)	(9.20%)
Allowance for uncollectible accounts, net of COVID-19 assistance	(2.90%)	0.50%	(1.60%)	(0.40%)
Cost of removal	3.00%	4.40%	1.50%	1.80%
Other plant-related items	0.00%	(2.40%)	0.00%	(0.40%)
Other	(1.10%)	(0.20%)	(0.30%)	(0.40%)
Effective tax rate	16.90%	(5.10%)	22.00%	15.90%
CECONY
Changes in computed taxes resulting from:
Effective tax rate	$ 48	$ 1	$ 275	$ 182
CECONY | Subsidiaries
STATUTORY TAX RATE
Federal	$ 57	$ 39	$ 261	$ 223
Federal	21.00%	21.00%	21.00%	21.00%
Changes in computed taxes resulting from:
State income taxes, net of federal income taxes (a)	$ 14	$ 9	$ 65	$ 55
MTA Surcredit amortization, net of federal taxes	7	2	20	2
Tax Credits	(3)	(3)	(7)	(6)
Changes in unrecognized tax benefits	1	1	2	1
Amortization of excess deferred federal income taxes (b)	(9)	(50)	(18)	(99)
Allowance for uncollectible accounts, net of COVID-19 assistance	(9)	1	(22)	(4)
Cost of removal	8	8	18	18
Other plant-related items	0	0	0	0
Other	4	2	4	4
Effective tax rate	$ 48	$ 1	$ 275	$ 182
Changes in computed taxes resulting from:
State income taxes, net of federal income taxes (a)	5.10%	5.00%	5.20%	5.20%
MTA Surcredit amortization, net of federal taxes	0.026	0.012	0.016	0.002
Tax Credits	(1.20%)	(1.70%)	(0.50%)	(0.60%)
Changes in unrecognized tax benefits	0.30%	0.30%	0.10%	0.10%
Amortization of excess deferred federal income taxes (b)	(3.30%)	(26.50%)	(1.50%)	(9.30%)
Allowance for uncollectible accounts, net of COVID-19 assistance	(3.30%)	0.60%	(1.70%)	(0.40%)
Cost of removal	3.00%	4.00%	1.50%	1.70%
Other plant-related items	0.00%	0.00%	0.00%	0.00%
Other	(1.20%)	(1.00%)	(0.30%)	(0.40%)
Effective tax rate	17.80%	0.50%	22.20%	17.10%