Leases - SPPC - Schedule of Operating and Finance Lease, Supplemental Cash Flow (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Operating cash flows from operating leases	$ (163)	$ (152)	$ (153)
Operating cash flows from finance leases	(38)	(40)	(42)
Financing cash flows from finance leases	(28)	(24)	(19)
Right-of-use assets obtained in exchange for lease liabilities:
Finance leases	2	19	14
SPPC
Lessee, Lease, Description [Line Items]
Operating cash flows from operating leases	(1)	(2)	(3)
Operating cash flows from finance leases	(9)	(6)	(3)
Financing cash flows from finance leases	(7)	(5)	(3)
Right-of-use assets obtained in exchange for lease liabilities:
Finance leases	$ 1	$ 89	$ 5