Material Contingencies - Guarantees (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 124	$ 175
Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	76
Guarantees on behalf of the Clean Energy Businesses
Guarantor Obligations [Line Items]
Total guarantees, by type and term	39
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	83
0 – 3 years | Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	76
0 – 3 years | Guarantees on behalf of the Clean Energy Businesses
Guarantor Obligations [Line Items]
Total guarantees, by type and term	7
0 – 3 years | Broken Bow II
Guarantor Obligations [Line Items]
Total guarantees, by type and term	0
4 – 10 years
Guarantor Obligations [Line Items]
Total guarantees, by type and term	7
4 – 10 years | Guarantees on behalf of the Clean Energy Businesses
Guarantor Obligations [Line Items]
Total guarantees, by type and term	7
4 – 10 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	34
Greater than 10 years | Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	0
Greater than 10 years | Guarantees on behalf of the Clean Energy Businesses
Guarantor Obligations [Line Items]
Total guarantees, by type and term	25
Greater than 10 years | Broken Bow II
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 9