Income Taxes - SPPC - Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Components of Income Tax Expense (Benefit) [Line Items]
Current - Federal	$ (1,463)	$ (1,701)	$ (1,537)
Deferred - Federal	(408)	1,037	1,438
Total	(1,916)	(1,132)	308
SPPC
Components of Income Tax Expense (Benefit) [Line Items]
Current - Federal	(12)	5	3
Deferred - Federal	31	13	12
Total	$ 19	$ 18	$ 15