Investments - Purchased with Credit Deterioration (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($)
Purchased financial assets with credit deterioration [Line Items]
Debt Securities, Available-for-sale, Purchased with Credit Deterioration, Amount at Purchase Price	$ 6
Debt Securities, Available-for-sale, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date	2
Debt Securities, Available-for-sale, Purchased with Credit Deterioration, Discount (Premium)	(2)
Debt Securities, Available-for-sale, Purchased with Credit Deterioration, Amount at Par Value	6
Mortgage loans
Purchased financial assets with credit deterioration [Line Items]
Financing Receivable, Purchased with Credit Deterioration, Amount at Purchase Price	335
Financing Receivable, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date	6
Financing Receivable, Purchased with Credit Deterioration, Discount (Premium)	(26)
Financing Receivable, Purchased with Credit Deterioration, Amount at Par Value	$ 315