Leases - SPPC - Schedule of Operating and Finance Lease (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Right-of-use assets:
Operating leases	$ 524	$ 517
Finance lease right of use assets, net	448	501
Total right-of-use assets	$ 972	$ 1,018
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other assets	Other assets
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other assets	Other assets
Lease liabilities:
Operating leases	$ 577	$ 569
Finance leases	463	514
Total lease liabilities	$ 1,040	$ 1,083
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Other current liabilities, Other long-term liabilities	Other current liabilities, Other long-term liabilities
Finance Lease, Liability, Statement of Financial Position [Extensible List]	Other current liabilities, Other long-term liabilities	Other current liabilities, Other long-term liabilities
SPPC
Right-of-use assets:
Operating leases	$ 15	$ 16
Finance lease right of use assets, net	111	126
Total right-of-use assets	$ 126	$ 142
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other assets	Other assets
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other assets	Other assets
Lease liabilities:
Operating leases	$ 15	$ 16
Finance leases	115	130
Total lease liabilities	$ 130	$ 146
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Other current liabilities, Other long-term liabilities	Other current liabilities, Other long-term liabilities
Finance Lease, Liability, Statement of Financial Position [Extensible List]	Other current liabilities, Other long-term liabilities	Other current liabilities, Other long-term liabilities