Regulatory Matters - Regulatory Assets (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	$ 4,334	$ 3,974
Regulatory assets – current	180	305
Total Regulatory Assets	4,514	4,279
Unrecognized pension and other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	125	78
Environmental remediation costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	983	991
Revenue taxes
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	468	436
Deferred storm costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	221	270
Municipal infrastructure support costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	20	29
Brooklyn Queens Demand Management (BQDM) program
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	31	33
Meadowlands heater odorization project
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	24	27
Recoverable Demonstration project costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	18	17
Gate station upgrade project
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	14	14
System peak reduction and energy efficiency programs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	868	783
Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	9	11
Deferred derivative losses - long term
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	99	31
Property tax reconciliation
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	195	121
Legacy meters
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	17	20
Gas service line deferred costs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	49	99
COVID - 19 customer arrears relief programs
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	418	104
Pension and other postretirement benefits deferrals
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	56	279
Preferred stock redemption
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	18	19
MTA power reliability deferral
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	69	92
Non-wire alternative projects
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	20	22
COVID - 19 pandemic deferrals
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	333	292
Electric vehicle make ready
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	59	33
Other
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	220	173
Deferred derivative losses - short term
Regulatory Assets [Line Items]
Regulatory assets – current	137	184
Recoverable energy costs
Regulatory Assets [Line Items]
Regulatory assets – current	43	121
CECONY
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	4,057	3,669
Regulatory assets – current	163	286
CECONY | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	4,057	3,669
Regulatory assets – current	163	286
Total Regulatory Assets	4,220	3,955
CECONY | Unrecognized pension and other postretirement costs | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	125	78
CECONY | Environmental remediation costs | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	899	906
CECONY | Revenue taxes | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	448	417
CECONY | Deferred storm costs | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	129	173
CECONY | Municipal infrastructure support costs | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	20	29
CECONY | Brooklyn Queens Demand Management (BQDM) program | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	31	33
CECONY | Meadowlands heater odorization project | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	24	27
CECONY | Recoverable Demonstration project costs | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	18	16
CECONY | Gate station upgrade project | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	14	14
CECONY | System peak reduction and energy efficiency programs | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	860	780
CECONY | Unamortized loss on reacquired debt | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	8	10
CECONY | Deferred derivative losses - long term | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	89	26
CECONY | Property tax reconciliation | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	195	121
CECONY | Legacy meters | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	0	0
CECONY | Gas service line deferred costs | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	49	99
CECONY | COVID - 19 customer arrears relief programs | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	415	101
CECONY | Pension and other postretirement benefits deferrals | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	41	240
CECONY | Preferred stock redemption | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	18	19
CECONY | MTA power reliability deferral | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	69	92
CECONY | Non-wire alternative projects | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	20	22
CECONY | COVID - 19 pandemic deferrals | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	329	288
CECONY | Electric vehicle make ready | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	55	30
CECONY | Other | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – noncurrent	201	148
CECONY | Deferred derivative losses - short term | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – current	132	178
CECONY | Recoverable energy costs | Subsidiaries
Regulatory Assets [Line Items]
Regulatory assets – current	$ 31	$ 108