Investments (Credit Loss Expense Incurred) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Gross credit loss expense recognized in net income (loss)	$ (2)	$ (20)
Net credit loss expense recognized in net income (loss)	(2)	(20)
Corporate Bonds [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Gross credit loss expense recognized in net income (loss)	$ (2)	$ (20)

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.

No definition available.

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