Summary of Significant Accounting Policies - SPPC - Reconciliation of Cash (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 1,591	$ 1,096
Investments and restricted cash and cash equivalents	173	127
Total cash and cash equivalents and restricted cash and cash equivalents	1,817	1,244	$ 1,445	$ 1,268
SPPC
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	49	10
Investments and restricted cash and cash equivalents	7	6
Total cash and cash equivalents and restricted cash and cash equivalents	$ 56	$ 16	$ 26	$ 32