Income Tax - Schedule of Differences on Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Deferred tax liabilities:
Property basis differences	$ 9,222	$ 8,542
Regulatory Assets:
Energy efficiency and other clean energy programs	464	351
Environmental remediation costs	291	310
Legacy meters	116	4
Other regulatory assets	571	574
Pensions and retiree benefits – asset	1,063	918
Operating lease right-of-use asset	143	154
Total deferred tax liabilities	11,870	10,853
Deferred tax assets:
Unrecognized pension and other postretirement costs	296	265
Future income tax	343	427
Other regulatory liabilities	909	844
Tax credits carryforward	346	270
Superfund and other environmental costs	291	314
Pensions and retiree benefits – liability	154	167
Corporate alternative minimum tax credit carryforward	139	0
Operating lease liabilities	143	154
Asset retirement obligations	127	146
Equity investments	80	98
Loss carryforwards	42	7
Valuation allowance	(12)	(7)
Other	160	125
Total deferred tax assets	3,018	2,810
Net deferred tax liabilities	8,852	8,043
Unamortized investment tax credits	22	26
Net deferred tax liabilities and unamortized investment tax credits	8,874	8,069
CECONY
Deferred tax liabilities:
Property basis differences	8,632	8,001
Regulatory Assets:
Energy efficiency and other clean energy programs	449	344
Environmental remediation costs	267	287
Legacy meters	112	0
Other regulatory assets	510	525
Pensions and retiree benefits – asset	1,037	894
Operating lease right-of-use asset	142	153
Total deferred tax liabilities	11,149	10,204
Deferred tax assets:
Unrecognized pension and other postretirement costs	276	244
Future income tax	312	394
Other regulatory liabilities	809	744
Tax credits carryforward	0	0
Superfund and other environmental costs	265	288
Pensions and retiree benefits – liability	142	153
Corporate alternative minimum tax credit carryforward	111	0
Operating lease liabilities	142	153
Asset retirement obligations	127	146
Equity investments	0	0
Loss carryforwards	16	0
Valuation allowance	0	0
Other	140	109
Total deferred tax assets	2,340	2,231
Net deferred tax liabilities	8,809	7,973
Unamortized investment tax credits	10	11
Net deferred tax liabilities and unamortized investment tax credits	$ 8,819	$ 7,984