Regulatory Matters - Schedule of Regulatory Assets Not Earning a Return (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Regulatory Assets [Line Items]
Regulatory assets not earning return	$ 1,986	$ 1,883
Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	1,843	1,753
Unrecognized pension and other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets not earning return	112	128
Unrecognized pension and other postretirement costs | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	89	110
Environmental remediation costs
Regulatory Assets [Line Items]
Regulatory assets not earning return	922	928
Environmental remediation costs | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	843	850
Revenue taxes
Regulatory Assets [Line Items]
Regulatory assets not earning return	388	375
Revenue taxes | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	372	359
COVID-19 Deferral for Uncollectible Accounts Receivable
Regulatory Assets [Line Items]
Regulatory assets not earning return	265	236
COVID-19 Deferral for Uncollectible Accounts Receivable | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	258	231
Deferred derivative losses - short term
Regulatory Assets [Line Items]
Regulatory assets not earning return	177	141
Deferred derivative losses - short term | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	165	134
Deferred derivative losses - long term
Regulatory Assets [Line Items]
Regulatory assets not earning return	85	51
Deferred derivative losses - long term | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	80	45
Other
Regulatory Assets [Line Items]
Regulatory assets not earning return	37	24
Other | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	$ 36	$ 24