Regulatory Matters - Schedule of Regulatory Assets Not Earning a Return (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Regulatory Assets [Line Items]
Regulatory assets not earning return	$ 2,108	$ 1,975
Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	1,987	1,858
Unrecognized pension and other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets not earning return	125	78
Unrecognized pension and other postretirement costs | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	125	78
Environmental remediation costs
Regulatory Assets [Line Items]
Regulatory assets not earning return	983	987
Environmental remediation costs | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	899	903
Revenue taxes
Regulatory Assets [Line Items]
Regulatory assets not earning return	494	414
Revenue taxes | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	474	397
COVID-19 Deferral for Uncollectible Accounts Receivable
Regulatory Assets [Line Items]
Regulatory assets not earning return	207	253
COVID-19 Deferral for Uncollectible Accounts Receivable | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	205	249
Deferred derivative losses - short term
Regulatory Assets [Line Items]
Regulatory assets not earning return	137	184
Deferred derivative losses - short term | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	133	178
Deferred derivative losses - long term
Regulatory Assets [Line Items]
Regulatory assets not earning return	99	31
Deferred derivative losses - long term | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	89	26
Other
Regulatory Assets [Line Items]
Regulatory assets not earning return	63	28
Other | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	$ 62	$ 27