Investments (Gains and Losses on Equity Investments) (Details) - SCE - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Investment Holdings [Line Items]
Gross realized gains	$ 255	$ 87	$ 134
Gross realized losses	(6)	(2)	(27)
Net unrealized gains (losses) for equity securities	$ 176	$ 343	$ (233)

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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