Material Contingencies - Guarantees (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 910	$ 2,412
Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	381
Guarantees on behalf of the Clean Energy Businesses
Guarantor Obligations [Line Items]
Total guarantees, by type and term	520
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	659
0 – 3 years | Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	381
0 – 3 years | Guarantees on behalf of the Clean Energy Businesses
Guarantor Obligations [Line Items]
Total guarantees, by type and term	278
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	16
4 – 10 years | Guarantees on behalf of the Clean Energy Businesses
Guarantor Obligations [Line Items]
Total guarantees, by type and term	16
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	235
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	226
Greater than 10 years | Broken Bow II
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 9