Regulatory Matters - Regulatory Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	$ 5,444.0	$ 5,328.0
Regulatory liabilities—current	102.0	145.0
Total Regulatory Liabilities	5,546.0	5,473.0
Regulatory assets	5,523.0	4,607.0
Future income tax
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,224.0	1,535.0
Allowance for cost of removal less salvage
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,527.0	1,456.0
Unrecognized pension and other postretirement costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,054.0	943.0
Pension and other postretirement benefit deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	368.0	284.0
Net unbilled revenue deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	436.0	278.0
Late payment charge deferral
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	231.0	167.0
System benefit charge carrying charge
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	115.0	92.0
Deferred derivative gains - long term
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	8.0	49.0
Net proceeds from sale of property
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	25.0	48.0
Settlement of prudence proceeding
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	10.0	11.0
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	446.0	465.0
Deferred derivative gains - short term
Regulatory Liabilities [Line Items]
Regulatory liabilities—current	25.0	74.0
Refundable energy costs
Regulatory Liabilities [Line Items]
Regulatory liabilities—current	59.0	71.0
Revenue decoupling mechanism
Regulatory Liabilities [Line Items]
Regulatory liabilities—current	18.0	0.0
CECONY
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	4,940.0	4,818.0
Regulatory liabilities—current	40.0	107.0
Regulatory assets	5,158.0	4,314.0
CECONY | Arrears Relief Program Deferral [Member]
Regulatory Liabilities [Line Items]
Regulatory assets	323.7	398.6
CECONY | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	4,940.0	4,818.0
Regulatory liabilities—current	40.0	107.0
Total Regulatory Liabilities	4,980.0	4,925.0
Regulatory assets	5,158.0	4,314.0
CECONY | Future income tax | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,112.0	1,404.0
CECONY | Allowance for cost of removal less salvage | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,322.0	1,266.0
CECONY | Unrecognized pension and other postretirement costs | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	984.0	867.0
CECONY | Pension and other postretirement benefit deferrals | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	304.0	233.0
CECONY | Net unbilled revenue deferrals | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	436.0	278.0
CECONY | Late payment charge deferral | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	224.0	161.0
CECONY | System benefit charge carrying charge | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	110.0	88.0
CECONY | Deferred derivative gains - long term | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	6.0	49.0
CECONY | Net proceeds from sale of property | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	24.0	47.0
CECONY | Settlement of prudence proceeding | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	10.0	11.0
CECONY | Other | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	408.0	414.0
CECONY | Deferred derivative gains - short term | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities—current	22.0	71.0
CECONY | Refundable energy costs | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities—current	18.0	36.0
CECONY | Revenue decoupling mechanism | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities—current	0.0	0.0
O&R | Arrears Relief Program Deferral [Member]
Regulatory Liabilities [Line Items]
Regulatory assets	$ 1.4	$ 2.1