Regulatory Matters - Regulatory Assets (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	$ 3,680	$ 3,639
Regulatory assets – current	289	206
Total Regulatory Assets	3,969	3,845
Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	3,351	3,316
Regulatory assets – current	269	188
Environmental remediation costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	933	938
Pension and other postretirement benefits deferrals
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	447	496
Revenue taxes
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	409	395
System peak reduction and energy efficiency programs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	330	285
COVID-19 pandemic deferrals
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	304	282
Deferred storm costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	292	276
Property tax reconciliation
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	178	202
MTA power reliability deferral
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	128	140
Unrecognized pension and other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	112	128
Deferred derivative losses - long term
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	85	51
Municipal infrastructure support costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	41	44
Brooklyn Queens demand management program
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	34	36
Meadowlands heater odorization project
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	29	29
Non-wire alternative projects
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	23	23
Preferred stock redemption
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	20	20
Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	14	16
Recoverable REV demonstration project costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	14	16
Gate station upgrade project
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	14	14
Other
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	273	248
Deferred derivative losses - short term
Regulatory Assets [Line Items]
Regulatory assets – current	177	141
Recoverable energy costs
Regulatory Assets [Line Items]
Regulatory assets – current	112	65
CECONY | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	3,351	3,316
Regulatory assets – current	269	188
Total Regulatory Assets	3,620	3,504
CECONY | Environmental remediation costs | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	854	860
CECONY | Pension and other postretirement benefits deferrals | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	392	435
CECONY | Revenue taxes | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	391	378
CECONY | System peak reduction and energy efficiency programs | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	329	284
CECONY | COVID-19 pandemic deferrals | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	297	277
CECONY | Deferred storm costs | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	178	158
CECONY | Property tax reconciliation | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	178	202
CECONY | MTA power reliability deferral | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	128	140
CECONY | Unrecognized pension and other postretirement costs | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	89	110
CECONY | Deferred derivative losses - long term | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	80	45
CECONY | Municipal infrastructure support costs | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	41	44
CECONY | Brooklyn Queens demand management program | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	34	36
CECONY | Meadowlands heater odorization project | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	29	29
CECONY | Non-wire alternative projects | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	23	23
CECONY | Preferred stock redemption | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	20	20
CECONY | Unamortized loss on reacquired debt | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	13	14
CECONY | Recoverable REV demonstration project costs | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	13	15
CECONY | Gate station upgrade project | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	14	14
CECONY | Other | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	248	232
CECONY | Deferred derivative losses - short term | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – current	165	133
CECONY | Recoverable energy costs | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – current	$ 104	$ 55