Short-term Debt and Credit Facilities - SPPC (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Line of Credit Facility [Line Items]
Credit facilities	$ 10,873	$ 11,281
Short-term debt	(1,119)	(2,009)
Net credit facilities	9,134	8,683
SPPC
Line of Credit Facility [Line Items]
Credit facilities	250	250
Short-term debt	0	(159)
Net credit facilities	$ 250	$ 91
SPPC | Line of credit
Line of Credit Facility [Line Items]
Weighted average interest rate	0.00%	0.86%
SPPC | Secured credit facility, $250 million, expiring June 2025 | Line of credit
Line of Credit Facility [Line Items]
Credit facilities	$ 250
Debt to capitalization ratio	0.65