Electricity and Gas Purchase Agreements - Summary of Capacity, Energy and Other Fixed Payments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Long-term Contract for Purchase of Electric Power [Line Items]
Capacity, energy and other fixed payments	$ 546	$ 596	$ 552
Astoria Generating Company
Long-term Contract for Purchase of Electric Power [Line Items]
Capacity, energy and other fixed payments	40	45	20
Brooklyn Navy Yard
Long-term Contract for Purchase of Electric Power [Line Items]
Capacity, energy and other fixed payments	134	165	139
Gas transportation and storage
Long-term Contract for Purchase of Electric Power [Line Items]
Capacity, energy and other fixed payments	372	386	393
CECONY
Long-term Contract for Purchase of Electric Power [Line Items]
Capacity, energy and other fixed payments	501	550	506
CECONY | Astoria Generating Company
Long-term Contract for Purchase of Electric Power [Line Items]
Capacity, energy and other fixed payments	40	45	20
CECONY | Brooklyn Navy Yard
Long-term Contract for Purchase of Electric Power [Line Items]
Capacity, energy and other fixed payments	134	165	139
CECONY | Gas transportation and storage
Long-term Contract for Purchase of Electric Power [Line Items]
Capacity, energy and other fixed payments	$ 327	$ 340	$ 347