Leases (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	[1]	$ 15	$ 14
Lessee, Operating Lease, Liability, to be Paid		587
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		(131)
Operating Lease, Liability		456
Operating Lease, Liability, Current		(30)		$ (30)
Operating lease liabilities		426		$ 434
PPAs
Lessee, Lease, Description [Line Items]
Operating Lease, Cost		13	13
Lessee, Operating Lease, Liability, to be Paid		532
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		(115)
Operating Lease, Liability		417
Property, Plant and Equipment, Other Types
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	[2]	2	$ 1
Lessee, Operating Lease, Liability, to be Paid		55
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		(16)
Operating Lease, Liability		$ 39

[1] PPA capacity payments are included in electric fuel and purchased power on the statements of income. Expense for other operating leases is included in operating and maintenance expense and electric fuel and purchased power.

[2] Includes immaterial short-term lease expense for 2022 and 2021.