Commitments and Contingencies, Leases (Details) - USD ($)		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Maximum Length - Short-Term Leases		12 months
Operating Lease, Weighted Average Discount Rate, Percent		4.40%
Short-term Lease, Cost		$ 1,000,000	$ 1,000,000	$ 2,000,000
Operating Lease, Assets and Liabilities, Lessee [Abstract]
Operating Lease, Right-of-Use Asset, Gross		545,000,000	550,000,000
Operating Lease, Right-of-Use Asset, Accumulated Depreciation		(82,000,000)	(58,000,000)
Operating lease right-of-use assets		463,000,000	492,000,000
Lease, Cost [Abstract]
Operating Lease, Cost	[1]	57,000,000	51,000,000	53,000,000
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2022		49,000,000
2023		49,000,000
2024		49,000,000
2025		50,000,000
2026		50,000,000
Thereafter		352,000,000
Total minimum obligation		599,000,000
Interest component of obligation		(135,000,000)
Operating lease liabilities		464,000,000
Less current portion		(30,000,000)	(28,000,000)
Operating Lease, Liability, Noncurrent		434,000,000	463,000,000
Weighted Average Remaining lease term, operating		12
Property, Plant and Equipment, Other Types [Member]
Operating Lease, Assets and Liabilities, Lessee [Abstract]
Operating Lease, Right-of-Use Asset, Gross		45,000,000	50,000,000
Lease, Cost [Abstract]
Operating Lease, Cost	[2]	4,000,000	3,000,000	5,000,000
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2022		3,000,000
2023		3,000,000
2024		3,000,000
2025		4,000,000
2026		4,000,000
Thereafter		40,000,000
Total minimum obligation		57,000,000
Interest component of obligation		(15,000,000)
Operating lease liabilities		42,000,000
Purchased Power Agreements
Operating Lease, Assets and Liabilities, Lessee [Abstract]
Operating Lease, Right-of-Use Asset, Gross		500,000,000	500,000,000
Lease, Cost [Abstract]
Operating Lease, Cost		53,000,000	$ 48,000,000	$ 48,000,000
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2022	[3],[4]	46,000,000
2023	[3],[4]	46,000,000
2024	[3],[4]	46,000,000
2025	[3],[4]	46,000,000
2026	[3],[4]	46,000,000
Thereafter	[3],[4]	312,000,000
Total minimum obligation	[3],[4]	542,000,000
Interest component of obligation	[3],[4]	(120,000,000)
Operating lease liabilities	[3],[4]	$ 422,000,000

[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 O&M expense.

[2] Includes short-term lease expense of $1 million, $1 million and $2 million for 2021, 2020 and 2019, respectively.

[3] Amounts do not include PPAs accounted for as executory contracts and/or contingent payments, such as energy payments on renewable PPAs.

[4] PPA operating leases contractually expire at various dates through 2033.