Investments - Purchased with Credit Deterioration (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Purchased financial assets with credit deterioration [Line Items]
Debt Securities, Available-for-sale, Purchased with Credit Deterioration, Amount at Purchase Price	$ 0	$ 239
Debt Securities, Available-for-sale, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date	0	61
Debt Securities, Available-for-sale, Purchased with Credit Deterioration, Discount (Premium)	0	34
Debt Securities, Available-for-sale, Purchased with Credit Deterioration, Amount at Par Value	0	334
Mortgage loans
Purchased financial assets with credit deterioration [Line Items]
Financing Receivable, Purchased with Credit Deterioration, Amount at Purchase Price	142	142
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date	3	3
Financing Receivable, Purchased with Credit Deterioration, Discount (Premium)	0	0
Financing Receivable, Purchased with Credit Deterioration, Amount at Par Value	$ 145	$ 145