Material Contingencies - Guarantees (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 63	$ 175
Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	54
Broken Bow II
Guarantor Obligations [Line Items]
Total guarantees, by type and term	9
0 – 3 years
Guarantor Obligations [Line Items]
Total guarantees, by type and term	54
0 – 3 years | Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	54
0 – 3 years | Broken Bow II
Guarantor Obligations [Line Items]
Total guarantees, by type and term	0
Greater than 10 years
Guarantor Obligations [Line Items]
Total guarantees, by type and term	9
Greater than 10 years | Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	0
Greater than 10 years | Broken Bow II
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 9