Regulatory Matters - Regulatory Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	$ 5,037	$ 5,328
Regulatory liabilities – current	143	145
Total Regulatory Liabilities	5,180	5,473
Regulatory assets	5,317	4,607
Regulatory assets	224	281
Allowance for cost of removal less salvage
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,470	1,456
Future income tax
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,324	1,535
Unrecognized pension and other postretirement costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	787	943
Pension and other postretirement benefit deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	370	284
Net unbilled revenue deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	260	278
Late payment charge deferral
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	227	167
System benefit charge carrying charge
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	111	92
Net proceeds from sale of property
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	31	48
Deferred derivative gains - long term
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	19	49
Settlement of prudence proceeding
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	10	11
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	428	465
Refundable energy costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	81	71
Revenue decoupling mechanism
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	33	0
Deferred derivative gains - short term
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	29	74
CECONY
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	4,561	4,818
Regulatory liabilities – current	71	107
Regulatory assets	4,971	4,314
Regulatory assets	193	254
CECONY | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	4,561	4,818
Regulatory liabilities – current	71	107
Total Regulatory Liabilities	4,632	4,925
Regulatory assets	4,971	4,314
Regulatory assets	193	254
CECONY | Allowance for cost of removal less salvage | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,269	1,266
CECONY | Future income tax | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,209	1,404
CECONY | Unrecognized pension and other postretirement costs | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	739	867
CECONY | Pension and other postretirement benefit deferrals | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	312	233
CECONY | Net unbilled revenue deferrals | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	260	278
CECONY | Late payment charge deferral | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	221	161
CECONY | System benefit charge carrying charge | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	106	88
CECONY | Net proceeds from sale of property | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	30	47
CECONY | Deferred derivative gains - long term | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	19	49
CECONY | Settlement of prudence proceeding | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	10	11
CECONY | Other | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	386	414
CECONY | Refundable energy costs | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	43	36
CECONY | Revenue decoupling mechanism | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	0	0
CECONY | Deferred derivative gains - short term | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	$ 28	$ 71