Investments (Rollforward of Total Amount of Credit-Related OTTI) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Net Investment Income [Line Items]
Interest income	$ 112	$ 71
Taxable
Net Investment Income [Line Items]
Interest income	98	60
Nontaxable
Net Investment Income [Line Items]
Interest income	14	11
Held-to-maturity
Net Investment Income [Line Items]
Interest income	3	5
Held-to-maturity | Taxable
Net Investment Income [Line Items]
Interest income	2	3
Held-to-maturity | Nontaxable
Net Investment Income [Line Items]
Interest income	1	2
Available-for-sale
Net Investment Income [Line Items]
Interest income	104	64
Available-for-sale | Taxable
Net Investment Income [Line Items]
Interest income	96	57
Available-for-sale | Nontaxable
Net Investment Income [Line Items]
Interest income	8	7
Trading
Net Investment Income [Line Items]
Interest income	5	2
Trading | Taxable
Net Investment Income [Line Items]
Interest income	0	0
Trading | Nontaxable
Net Investment Income [Line Items]
Interest income	$ 5	$ 2