Income Tax - Schedule of Differences on Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Deferred tax liabilities:
Property basis differences	$ 8,770	$ 8,298
Regulatory Assets:
Deferred storm costs	27	33
Environmental remediation costs	278	264
Other regulatory assets	754	640
Unrecognized pension and other postretirement costs	22	36
Pensions and retiree benefits – asset	917	478
Operating lease right-of-use asset	230	204
Equity investments	26	0
Other	0	30
Total deferred tax liabilities	11,024	9,983
Deferred tax assets:
Unrecognized pension and other postretirement costs	447	0
Future income tax	489	554
Other regulatory liabilities	860	727
Tax credits carryforward	767	946
Loss carryforwards	117	144
Valuation allowance	(18)	(22)
Superfund and other environmental costs	280	264
Operating lease liabilities	233	195
Pensions and retiree benefits – liability	162	218
Asset retirement obligations	153	177
Equity investments	0	34
Other	14	0
Total deferred tax assets	3,504	3,237
Net deferred tax liabilities	7,520	6,746
Unamortized investment tax credits	121	127
Net deferred tax liabilities and unamortized investment tax credits	7,641	6,873
CECONY
Deferred tax liabilities:
Property basis differences	7,475	7,213
Regulatory Assets:
Deferred storm costs	0	0
Environmental remediation costs	254	241
Other regulatory assets	720	609
Unrecognized pension and other postretirement costs	22	31
Pensions and retiree benefits – asset	894	471
Operating lease right-of-use asset	163	155
Equity investments	0	0
Other	0	0
Total deferred tax liabilities	9,528	8,720
Deferred tax assets:
Unrecognized pension and other postretirement costs	431	0
Future income tax	454	517
Other regulatory liabilities	739	620
Tax credits carryforward	0	0
Loss carryforwards	24	38
Valuation allowance	0	0
Superfund and other environmental costs	254	238
Operating lease liabilities	162	155
Pensions and retiree benefits – liability	148	188
Asset retirement obligations	140	141
Equity investments	0	0
Other	45	42
Total deferred tax assets	2,397	1,939
Net deferred tax liabilities	7,131	6,781
Unamortized investment tax credits	13	15
Net deferred tax liabilities and unamortized investment tax credits	$ 7,144	$ 6,796