Income Taxes - SPPC - Reconciliation of Effective Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Effective Income Tax Rate Reconciliation [Line Items]
Federal statutory income tax rate	21.00%	21.00%	21.00%
Effects of ratemaking	(16.00%)	(4.00%)	(3.00%)
Effective income tax rate	(136.00%)	(21.00%)	4.00%
SPPC
Schedule of Effective Income Tax Rate Reconciliation [Line Items]
Federal statutory income tax rate	21.00%	21.00%	21.00%
Effects of ratemaking	(7.00%)	(8.00%)	(9.00%)
Effective income tax rate	14.00%	13.00%	12.00%