Regulatory Matters - Regulatory Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	$ 5,401	$ 6,027
Regulatory liabilities – current	189	374
Total Regulatory Liabilities	5,590	6,401
Future income tax
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,583	1,753
Allowance for cost of removal less salvage
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,368	1,315
Net unbilled revenue deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	214	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	8	10
Earnings sharing - electric, gas and steam
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	13	13
System benefit charge carrying charge
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	87	73
BQDM and Demonstration project reconciliations
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	15	23
Pension and other postretirement benefit deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	194	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	1	12
Late payment charge deferral
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	160	127
Unrecognized pension and other postretirement costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,276	1,638
Net proceeds from sale of property
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	54	69
Sales and use tax refunds
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	29	37
Workers’ compensation
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	15	11
Deferred derivative gains - long term
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	17	145
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	327	413
Refundable energy costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	99	34
Revenue decoupling mechanism
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	0	29
Deferred derivative gains - short term
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	90	311
CECONY
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	4,890	5,481
Regulatory liabilities – current	153	308
CECONY | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	4,890	5,481
Regulatory liabilities – current	153	308
Total Regulatory Liabilities	5,043	5,789
CECONY | Future income tax | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,450	1,616
CECONY | Allowance for cost of removal less salvage | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,181	1,137
CECONY | Net unbilled revenue deferrals | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	214	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	8	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	83	69
CECONY | BQDM and Demonstration project reconciliations | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	15	21
CECONY | Pension and other postretirement benefit deferrals | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	146	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	1	12
CECONY | Late payment charge deferral | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	155	123
CECONY | Unrecognized pension and other postretirement costs | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,197	1,536
CECONY | Net proceeds from sale of property | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	52	69
CECONY | Sales and use tax refunds | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	27	36
CECONY | Workers’ compensation | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	15	11
CECONY | Deferred derivative gains - long term | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	17	130
CECONY | Other | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	277	357
CECONY | Refundable energy costs | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	70	0
CECONY | Revenue decoupling mechanism | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	0	21
CECONY | Deferred derivative gains - short term | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	$ 83	$ 287