Other Postretirement Benefits - Schedule of Fair Values of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	$ 583	$ 524
CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	560	502
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	934	929	$ 860	$ 1,150
Other Postretirement Benefits | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	744	750	$ 708	$ 955
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Total investments
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	736	717
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Total investments | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	548	540
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Equity
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	302	331
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Equity | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	205	241
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Other Fixed Income Debt
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	323	323
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Other Fixed Income Debt | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	233	237
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	34	25
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Cash and Cash Equivalents | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	33	24
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Commingled Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	38	38
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Commingled Trust Fund | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	38	38
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Real Estate and Other Alternatives
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	39
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Real Estate and Other Alternatives | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	39
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Funds For Retiree Health Benefits
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	140	148
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Funds For Retiree Health Benefits | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	140	148
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Investments, Including Funds For Retiree Health Benefit
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	876	865
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Investments, Including Funds For Retiree Health Benefit | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	688	688
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Funds For Retiree Health Benefits Measured At Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	39	45
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Funds For Retiree Health Benefits Measured At Net Asset Value | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	39	45
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Pending Activities
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	19	19
Other Postretirement Benefits | Fair Value, Inputs, Level 1 and 2 | Pending Activities | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	17	17
Other Postretirement Benefits | Level 1 | Total investments
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	7	7
Other Postretirement Benefits | Level 1 | Total investments | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	7	7
Other Postretirement Benefits | Level 1 | Equity
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	0	0
Other Postretirement Benefits | Level 1 | Equity | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	0	0
Other Postretirement Benefits | Level 1 | Other Fixed Income Debt
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	0	0
Other Postretirement Benefits | Level 1 | Other Fixed Income Debt | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	0	0
Other Postretirement Benefits | Level 1 | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	7	7
Other Postretirement Benefits | Level 1 | Cash and Cash Equivalents | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	7	7
Other Postretirement Benefits | Level 1 | Commingled Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	0	0
Other Postretirement Benefits | Level 1 | Commingled Trust Fund | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	0	0
Other Postretirement Benefits | Level 1 | Funds For Retiree Health Benefits
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	50	52
Other Postretirement Benefits | Level 1 | Funds For Retiree Health Benefits | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	50	52
Other Postretirement Benefits | Level 1 | Investments, Including Funds For Retiree Health Benefit
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	57	59
Other Postretirement Benefits | Level 1 | Investments, Including Funds For Retiree Health Benefit | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	57	59
Other Postretirement Benefits | Level 2 | Total investments
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	690	710
Other Postretirement Benefits | Level 2 | Total investments | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	502	533
Other Postretirement Benefits | Level 2 | Equity
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	302	331
Other Postretirement Benefits | Level 2 | Equity | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	205	241
Other Postretirement Benefits | Level 2 | Other Fixed Income Debt
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	323	323
Other Postretirement Benefits | Level 2 | Other Fixed Income Debt | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	233	237
Other Postretirement Benefits | Level 2 | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	27	18
Other Postretirement Benefits | Level 2 | Cash and Cash Equivalents | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	26	17
Other Postretirement Benefits | Level 2 | Commingled Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	38	38
Other Postretirement Benefits | Level 2 | Commingled Trust Fund | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	38	38
Other Postretirement Benefits | Level 2 | Funds For Retiree Health Benefits
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	90	96
Other Postretirement Benefits | Level 2 | Funds For Retiree Health Benefits | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	90	96
Other Postretirement Benefits | Level 2 | Investments, Including Funds For Retiree Health Benefit
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	780	806
Other Postretirement Benefits | Level 2 | Investments, Including Funds For Retiree Health Benefit | CECONY
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	$ 592	$ 629