Regulatory Matters - Schedule of Regulatory Assets Not Earning a Return (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Regulatory Assets [Line Items]
Regulatory assets not earning return	$ 2,446	$ 2,347
Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	2,291	2,209
Environmental remediation costs
Regulatory Assets [Line Items]
Regulatory assets not earning return	1,093	1,105
Environmental remediation costs | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	1,009	1,022
Revenue taxes
Regulatory Assets [Line Items]
Regulatory assets not earning return	558	490
Revenue taxes | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	535	470
COVID-19 deferral for uncollectible accounts receivable
Regulatory Assets [Line Items]
Regulatory assets not earning return	391	291
COVID-19 deferral for uncollectible accounts receivable | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	384	288
Deferred derivative losses - short term
Regulatory Assets [Line Items]
Regulatory assets not earning return	165	269
Deferred derivative losses - short term | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	152	253
Deferred derivative losses - long term
Regulatory Assets [Line Items]
Regulatory assets not earning return	154	163
Deferred derivative losses - long term | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	138	148
Unrecognized pension and other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets not earning return	10	0
Unrecognized pension and other postretirement costs | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	10	0
Other
Regulatory Assets [Line Items]
Regulatory assets not earning return	75	29
Other | Subsidiaries | CECONY
Regulatory Assets [Line Items]
Regulatory assets not earning return	$ 63	$ 28