Material Contingencies - Guarantees (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 218	$ 2,412
Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	78
Guarantees on behalf of the Clean Energy Businesses
Guarantor Obligations [Line Items]
Total guarantees, by type and term	131
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	178
0 – 3 years | Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	78
0 – 3 years | Guarantees on behalf of the Clean Energy Businesses
Guarantor Obligations [Line Items]
Total guarantees, by type and term	100
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	0
4 – 10 years | Guarantees on behalf of the Clean Energy Businesses
Guarantor Obligations [Line Items]
Total guarantees, by type and term	0
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	40
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	31
Greater than 10 years | Broken Bow II
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 9