Summary of Significant Accounting Policies (Emission Allowances) (Details) - SCE - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Significant Accounting Policies [Line Items]
Regulatory liabilities	$ 9,584	$ 9,158
LCFS net sales proceeds
Significant Accounting Policies [Line Items]
Regulatory liabilities	193	176
Other Current Assets
Significant Accounting Policies [Line Items]
GHG allowances	47	78
Other Current Liabilities
Significant Accounting Policies [Line Items]
GHG emission obligations	$ 34	$ 64