Investments (Rollforward of expected credit losses AFS) (Details) - USD ($) $ in Millions		12 Months Ended
Jan. 01, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss		$ 14	$ 20	$ 0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase		0	5
Debt Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease)		14	188
Debt Securities, Available-for-sale, Allowance for Credit Loss, Recovery		(20)	(193)
Debt Securities, Available-for-sale, Allowance for Credit Loss, Writeoff		0	(5)
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax		3,220	5,655
Debt Securities, Held-to-maturity, Allowance for Credit Loss		35	44	0
Debt Securities, Held-to-maturity, Allowance for Credit Loss, Recovery		(10)	(9)
Mortgage-backed securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss		0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax		532	1,022
Debt Securities, Held-to-maturity, Allowance for Credit Loss		1	1
-72000000
Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items]
Debt Securities, Available-for-sale, Allowance for Credit Loss			0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease)		$ 14	11	$ 0
Debt Securities, Held-to-maturity, Allowance for Credit Loss	$ 44		$ 0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded	$ 25

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of increase (decrease) in allowance for credit loss of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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