Amount of allowance for credit loss for debt security measured at amortized cost (held-to-maturity).

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Amount of increase (decrease) in allowance for credit loss on investment in debt security measured at amortized cost (held-to-maturity).

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-Publisher FASB
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Amount of increase in allowance for credit loss on investment in debt security measured at amortized cost (held-to-maturity), from recovery.

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Investments (Rollforward of expected credit losses HTM) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Debt Securities, Held-to-maturity, Allowance for Credit Loss	$ 37	$ 51	$ 37	$ 51	$ 43	$ 44	$ 45		$ 0
Debt Securities, Held-to-maturity, Allowance for Credit Loss, Recovery	(6)	0	(7)	0
Accounting Standards Update 2016-13 [Member]
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Debt Securities, Held-to-maturity, Allowance for Credit Loss								$ 44
Debt Securities, Held-to-maturity, Allowance for Credit Loss, Period Increase (Decrease)	$ 0	$ 6	$ 0	$ 7