Regulatory Matters - Regulatory Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	$ 5,174	$ 5,328
Regulatory liabilities – current	258	145
Total Regulatory Liabilities	5,432	5,473
Regulatory assets	5,050	4,607
Future income tax
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,469	1,535
Allowance for cost of removal less salvage
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,468	1,456
Unrecognized pension and other postretirement costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	798	943
Pension and other postretirement benefit deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	315	284
Net unbilled revenue deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	288	278
Late payment charge deferral
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	205	167
System benefit charge carrying charge
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	98	92
Deferred derivative gains - long term
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	48	49
Net proceeds from sale of property
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	42	48
Settlement of prudence proceeding
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	11	11
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	432	465
Deferred derivative gains - short term
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	117	74
Refundable energy costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	140	71
Revenue decoupling mechanism
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	1	0
CECONY
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	4,687	4,818
Regulatory liabilities – current	210	107
Regulatory assets	4,757	4,314
CECONY | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	4,687	4,818
Regulatory liabilities – current	210	107
Total Regulatory Liabilities	4,897	4,925
Regulatory assets	4,757	4,314
CECONY | Future income tax | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,339	1,404
CECONY | Allowance for cost of removal less salvage | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,274	1,266
CECONY | Unrecognized pension and other postretirement costs | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	750	867
CECONY | Pension and other postretirement benefit deferrals | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	263	233
CECONY | Net unbilled revenue deferrals | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	288	278
CECONY | Late payment charge deferral | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	198	161
CECONY | System benefit charge carrying charge | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	93	88
CECONY | Deferred derivative gains - long term | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	47	49
CECONY | Net proceeds from sale of property | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	41	47
CECONY | Settlement of prudence proceeding | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	11	11
CECONY | Other | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	383	414
CECONY | Deferred derivative gains - short term | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	110	71
CECONY | Refundable energy costs | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	100	36
CECONY | Revenue decoupling mechanism | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	$ 0	$ 0