Regulatory Matters - Regulatory Assets (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	$ 3,639	$ 6,195
Regulatory assets – current	206	266
Total Regulatory Assets	3,845	6,461
Regulatory assets not earning return	1,883	4,823
Unrecognized pension and other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	128	3,241
Regulatory assets not earning return	128	3,241
Environmental remediation costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	938	865
Regulatory assets not earning return	928	855
Revenue taxes
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	395	356
Regulatory assets not earning return	375	336
Pension and other postretirement benefits deferrals
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	496	315
Property tax reconciliation
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	202	241
Deferred storm costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	276	195
MTA power reliability deferral
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	140	188
System peak reduction and energy efficiency programs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	285	124
Deferred derivative losses
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	51	120
Regulatory assets not earning return	51	120
COVID - 19 Deferrals
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	282	115
Municipal infrastructure support costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	44	62
Brooklyn Queens demand management program
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	36	36
Meadowlands heater odorization project
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	29	32
Gate station upgrade project
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	14	25
Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	16	21
Preferred stock redemption
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	20	21
Recoverable REV demonstration project costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	16	20
Non-wire alternative projects
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	23	18
COVID-19 Deferral for Uncollectible Accounts Receivable
Regulatory Assets [Line Items]
Regulatory assets not earning return	236	57
Other
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	248	200
Regulatory assets not earning return	24	24
Deferred derivative losses
Regulatory Assets [Line Items]
Regulatory assets – current	141	190
Regulatory assets not earning return	141	190
Recoverable energy costs
Regulatory Assets [Line Items]
Regulatory assets – current	65	76
CECONY
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	3,316	5,745
Regulatory assets – current	188	244
Total Regulatory Assets	3,504	5,989
Regulatory assets not earning return	1,753	4,536
CECONY | Unrecognized pension and other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	110	3,065
Regulatory assets not earning return	110	3,065
CECONY | Environmental remediation costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	860	791
Regulatory assets not earning return	850	781
CECONY | Revenue taxes
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	378	342
Regulatory assets not earning return	359	323
CECONY | Pension and other postretirement benefits deferrals
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	435	272
CECONY | Property tax reconciliation
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	202	239
CECONY | Deferred storm costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	158	83
CECONY | MTA power reliability deferral
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	140	188
CECONY | System peak reduction and energy efficiency programs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	284	124
CECONY | Deferred derivative losses
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	45	111
Regulatory assets not earning return	45	111
CECONY | COVID - 19 Deferrals
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	277	113
CECONY | Municipal infrastructure support costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	44	62
CECONY | Brooklyn Queens demand management program
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	36	36
CECONY | Meadowlands heater odorization project
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	29	32
CECONY | Gate station upgrade project
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	14	25
CECONY | Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	14	19
CECONY | Preferred stock redemption
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	20	21
CECONY | Recoverable REV demonstration project costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	15	18
CECONY | Non-wire alternative projects
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	23	18
CECONY | COVID-19 Deferral for Uncollectible Accounts Receivable
Regulatory Assets [Line Items]
Regulatory assets not earning return	231	55
CECONY | Other
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	232	186
Regulatory assets not earning return	24	24
CECONY | Deferred derivative losses
Regulatory Assets [Line Items]
Regulatory assets – current	133	177
Regulatory assets not earning return	134	177
CECONY | Recoverable energy costs
Regulatory Assets [Line Items]
Regulatory assets – current	$ 55	$ 67