Commitments and Contingencies - Leases (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2023		Sep. 30, 2022		Sep. 30, 2023		Sep. 30, 2022		Dec. 31, 2022
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	$ 28	[1]	$ 25	[1]	$ 83	[2]	$ 83	[2]
Finance Lease, Right-of-Use Asset, Amortization	1		1		2		3
Finance Lease, Interest Expense	4		4		12		12
Finance Lease, Cost	5		5		14		15
Lessee, Operating Lease, Liability, Payments, Due	457				457
Total minimum obligation	423				423
Interest component of obligation	(45)				(45)
Finance Lease, Liability, Undiscounted Excess Amount	(308)				(308)
Operating Lease, Liability	412				412
Finance Lease, Liability	115				115
Less current portion	(97)				(97)				$ (80)
Less current portion	(3)				(3)
Operating lease liabilities	315				315				$ 379
Noncurrent operating and finance lease liabilities	112				112
PPAs
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	23		22		68		70
Lessee, Operating Lease, Liability, Payments, Due	394				394
Interest component of obligation	(38)				(38)
Operating Lease, Liability	356				356
Other
Lessee, Lease, Description [Line Items]
Operating Lease, Cost	5	[3]	$ 3	[3]	15	[4]	$ 13	[4]
Lessee, Operating Lease, Liability, Payments, Due	63				63
Interest component of obligation	(7)				(7)
Operating Lease, Liability	$ 56				$ 56

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

[2] PPA capacity payments are included in electric fuel and purchased power on the consolidated statements of income. Expense for other operating leases is included in O&M expense and electric fuel and purchased power.

[3] Includes immaterial short-term lease expense for both 2023 and 2022.

[4] Includes immaterial short-term lease expense for both 2023 and 2022.