Electricity and Gas Purchase Agreements - Summary of Capacity, Energy and Other Fixed Payments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Long-term Contract for Purchase of Electric Power [Line Items]
Capacity, energy and other fixed payments	$ 636	$ 546	$ 596
Astoria Generating Company
Long-term Contract for Purchase of Electric Power [Line Items]
Capacity, energy and other fixed payments	75	40	45
Brooklyn Navy Yard
Long-term Contract for Purchase of Electric Power [Line Items]
Capacity, energy and other fixed payments	139	134	165
Gas transportation and storage
Long-term Contract for Purchase of Electric Power [Line Items]
Capacity, energy and other fixed payments	422	372	386
CECONY
Long-term Contract for Purchase of Electric Power [Line Items]
Capacity, energy and other fixed payments	586	501	550
CECONY | Astoria Generating Company
Long-term Contract for Purchase of Electric Power [Line Items]
Capacity, energy and other fixed payments	75	40	45
CECONY | Brooklyn Navy Yard
Long-term Contract for Purchase of Electric Power [Line Items]
Capacity, energy and other fixed payments	139	134	165
CECONY | Gas transportation and storage
Long-term Contract for Purchase of Electric Power [Line Items]
Capacity, energy and other fixed payments	$ 372	$ 327	$ 340