Investments (Net Investment Income - Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Income (Loss) from Equity Method Investments	$ 829	$ 795	$ 592

Amount of income (loss) for proportionate share of equity method investee's income (loss).

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