Regulatory Matters - Regulatory Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	$ 5,537	$ 6,027
Regulatory liabilities – current	278	374
Total Regulatory Liabilities	5,815	6,401
Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	5,017	5,481
Regulatory liabilities – current	213	308
Future income tax
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,694	1,753
Allowance for cost of removal less salvage
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,335	1,315
Net unbilled revenue deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	108	204
Energy efficiency portfolio standard unencumbered funds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	5	5
Settlement of prudence proceeding
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	9	10
Earnings sharing - electric, gas and steam
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	14	13
System benefit charge carrying charge
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	76	73
BQDM and Demonstration project reconciliations
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	21	23
Pension and other postretirement benefit deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	161	144
Property tax refunds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	35	35
COVID - 19 pandemic uncollectible reconciliation deferral
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	10	12
Late payment charge deferral
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	142	127
Unrecognized pension and other postretirement costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,405	1,638
Net proceeds from sale of property
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	65	69
Sales and use tax refunds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	35	37
Workers’ compensation
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	12	11
Deferred derivative gains - long term
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	19	145
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	391	413
Refundable energy costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	111	34
Revenue decoupling mechanism
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	5	29
Deferred derivative gains - short term
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	162	311
CECONY | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	5,017	5,481
Regulatory liabilities – current	213	308
Total Regulatory Liabilities	5,230	5,789
CECONY | Future income tax | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,559	1,616
CECONY | Allowance for cost of removal less salvage | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,153	1,137
CECONY | Net unbilled revenue deferrals | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	108	204
CECONY | Energy efficiency portfolio standard unencumbered funds | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	7	7
CECONY | Settlement of prudence proceeding | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	9	10
CECONY | Earnings sharing - electric, gas and steam | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	10	10
CECONY | System benefit charge carrying charge | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	74	69
CECONY | BQDM and Demonstration project reconciliations | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	19	21
CECONY | Pension and other postretirement benefit deferrals | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	115	98
CECONY | Property tax refunds | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	35	35
CECONY | COVID - 19 pandemic uncollectible reconciliation deferral | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	10	12
CECONY | Late payment charge deferral | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	137	123
CECONY | Unrecognized pension and other postretirement costs | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,316	1,536
CECONY | Net proceeds from sale of property | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	63	69
CECONY | Sales and use tax refunds | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	33	36
CECONY | Workers’ compensation | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	12	11
CECONY | Deferred derivative gains - long term | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	19	130
CECONY | Other | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	338	357
CECONY | Refundable energy costs | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	61	0
CECONY | Revenue decoupling mechanism | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	2	21
CECONY | Deferred derivative gains - short term | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	$ 150	$ 287