Regulatory Matters - Schedule of Regulatory Assets Not Earning a Return (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Regulatory Assets [Line Items]
Regulatory assets not earning return	$ 2,576	$ 2,402
Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	2,409	2,240
Environmental investigation and remediation costs
Regulatory Assets [Line Items]
Regulatory assets not earning return	1,023	1,037
Environmental investigation and remediation costs | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	937	942
Revenue taxes
Regulatory Assets [Line Items]
Regulatory assets not earning return	589	567
Revenue taxes | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	564	543
UB deferral for uncollectible accounts receivable
Regulatory Assets [Line Items]
Regulatory assets not earning return	547	551
UB deferral for uncollectible accounts receivable | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	541	541
Deferred derivative losses - short term
Regulatory Assets [Line Items]
Regulatory assets not earning return	207	102
Deferred derivative losses - short term | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	190	92
Deferred derivative losses - long term
Regulatory Assets [Line Items]
Regulatory assets not earning return	148	106
Deferred derivative losses - long term | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	133	94
Unrecognized pension and other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets not earning return	9	0
Unrecognized pension and other postretirement costs | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	4	0
Other
Regulatory Assets [Line Items]
Regulatory assets not earning return	53	39
Other | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	$ 40	$ 28