Material Contingencies - Guarantees (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 2,232	$ 2,157
Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	442
Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	807
Renewable electric projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	761
Other
Guarantor Obligations [Line Items]
Total guarantees, by type and term	222
0 – 3 years
Guarantor Obligations [Line Items]
Total guarantees, by type and term	1,489
0 – 3 years | Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	442
0 – 3 years | Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	493
0 – 3 years | Renewable electric projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	332
0 – 3 years | Other
Guarantor Obligations [Line Items]
Total guarantees, by type and term	222
4 – 10 years
Guarantor Obligations [Line Items]
Total guarantees, by type and term	91
4 – 10 years | Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	22
4 – 10 years | Renewable electric projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	69
4 – 10 years | Other
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	652
Greater than 10 years | Con Edison Transmission
Guarantor Obligations [Line Items]
Total guarantees, by type and term	0
Greater than 10 years | Energy transactions
Guarantor Obligations [Line Items]
Total guarantees, by type and term	292
Greater than 10 years | Renewable electric projects
Guarantor Obligations [Line Items]
Total guarantees, by type and term	360
Greater than 10 years | Other
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 0