Regulatory Matters - Schedule of Regulatory Assets Not Earning a Return (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Regulatory Assets [Line Items]
Regulatory assets not earning return	$ 2,453	$ 2,402
Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	2,295	2,240
Environmental investigation and remediation costs
Regulatory Assets [Line Items]
Regulatory assets not earning return	1,019	1,037
Environmental investigation and remediation costs | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	933	942
Revenue taxes
Regulatory Assets [Line Items]
Regulatory assets not earning return	595	567
Revenue taxes | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	569	543
UB deferral for uncollectible accounts receivable
Regulatory Assets [Line Items]
Regulatory assets not earning return	546	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	107	102
Deferred derivative losses - short term | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	97	92
Deferred derivative losses - long term
Regulatory Assets [Line Items]
Regulatory assets not earning return	105	106
Deferred derivative losses - long term | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	93	94
Unrecognized pension and other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets not earning return	15	0
Unrecognized pension and other postretirement costs | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	9	0
Other
Regulatory Assets [Line Items]
Regulatory assets not earning return	66	39
Other | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	$ 53	$ 28