Regulatory Matters - Regulatory Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	$ 5,028	$ 5,374
Regulatory liabilities – current	348	249
Total Regulatory Liabilities	5,376	5,623
Allowance for cost of removal less salvage
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,718	1,686
Future income tax
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,107	1,120
Unrecognized pension and other postretirement costs
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	810	873
Pension and other postretirement benefit deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	294	356
Net unbilled revenue deferrals
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	223	397
Late payment charge deferral
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	141	192
System benefit charge carrying charge
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	104	108
Deferred derivative gains - long term
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	68	119
Storm reserve passback
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	72	80
Settlement of prudence proceeding
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	8	8
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	483	435
Deferred derivative gains
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	229	165
Revenue decoupling mechanism liabilities
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	78	13
Deferred derivative gains - short term
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	41	71
CECONY
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	4,514	4,879
Regulatory liabilities – current	262	205
CECONY | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	4,514	4,879
Regulatory liabilities – current	262	205
Total Regulatory Liabilities	4,776	5,084
CECONY | Allowance for cost of removal less salvage | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	1,497	1,468
CECONY | Future income tax | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	994	1,015
CECONY | Unrecognized pension and other postretirement costs | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	743	806
CECONY | Pension and other postretirement benefit deferrals | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	243	313
CECONY | Net unbilled revenue deferrals | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	223	397
CECONY | Late payment charge deferral | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	141	191
CECONY | System benefit charge carrying charge | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	95	100
CECONY | Deferred derivative gains - long term | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	61	109
CECONY | Storm reserve passback | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	72	80
CECONY | Settlement of prudence proceeding | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	8	8
CECONY | Other | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – noncurrent	437	392
CECONY | Deferred derivative gains | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	210	152
CECONY | Revenue decoupling mechanism liabilities | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	51	0
CECONY | Deferred derivative gains - short term | Subsidiaries
Regulatory Liabilities [Line Items]
Regulatory liabilities – current	$ 1	$ 53