Other Postretirement Benefits - Schedule of Plan Assets Allocations (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 | Equity Securities | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	0	0
Other Postretirement Benefits | Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	302	331
Other Postretirement Benefits | Equity Securities | Fair Value, Inputs, Level 1 and 2
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	302	$ 331
Other Postretirement Benefits | Real Estate and Other Alternatives | Fair Value, Inputs, Level 1 and 2
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	$ 39
Other Postretirement Benefits | CECONY
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Range (percent)	100.00%
Plan Assets Percentage (percent)	100.00%	100.00%	100.00%
Total fair value of plan net assets	$ 744	$ 750	$ 708	$ 955
Other Postretirement Benefits | CECONY | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan Assets Percentage (percent)	41.00%	44.00%	49.00%
Other Postretirement Benefits | CECONY | Equity Securities | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	$ 0	$ 0
Other Postretirement Benefits | CECONY | Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	205	241
Other Postretirement Benefits | CECONY | Equity Securities | Fair Value, Inputs, Level 1 and 2
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	$ 205	$ 241
Other Postretirement Benefits | CECONY | Equity Securities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Range (percent)	35.00%
Other Postretirement Benefits | CECONY | Equity Securities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Range (percent)	55.00%
Other Postretirement Benefits | CECONY | Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Plan Assets Percentage (percent)	51.00%	51.00%	51.00%
Other Postretirement Benefits | CECONY | Debt Securities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Range (percent)	40.00%
Other Postretirement Benefits | CECONY | Debt Securities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Range (percent)	60.00%
Other Postretirement Benefits | CECONY | Real Estate and Other Alternatives
Defined Benefit Plan Disclosure [Line Items]
Plan Assets Percentage (percent)	8.00%	5.00%	0.00%
Other Postretirement Benefits | CECONY | Real Estate and Other Alternatives | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Range (percent)	0.00%
Other Postretirement Benefits | CECONY | Real Estate and Other Alternatives | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Range (percent)	9.00%
Other Postretirement Benefits | CECONY | Real Estate and Other Alternatives | Fair Value, Inputs, Level 1 and 2
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	$ 39