Investments (Gains and Losses on Equity Investments) (Details) - SCE - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Investment Holdings [Line Items]
Gross realized gains	$ 111	$ 39
Gross realized losses	(12)	(2)
Net unrealized gains (losses) for equity securities	$ 18	$ (376)

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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