Investments, Allowance for Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Investments [Abstract]
Accrued interest receivables on available-for-sale fixed maturity securities	$ 389	$ 390	$ 371
Allowance for Credit Losses [Roll Forward]
Beginning balance	40	0
Additions to allowance for securities for which credit losses were not previously recorded	14	48
Additions to allowance for available-for-sale securities accounted for as PCD assets	2	1
Reductions for securities sold during the period (realized)	6	5
Reductions for intent to sell or more likely than not will be required to sell the security before recovery of its amortized cost basis		1
Additional decreases to the allowance for credit losses on securities that had an allowance recorded in a previous period	(7)
Total allowance for credit losses	43	49
Cumulative Effect, Period of Adoption, Adjustment [Member] | ASC 326 [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance		6
Corporate and Other Bonds [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	23	0
Additions to allowance for securities for which credit losses were not previously recorded	14	48
Additions to allowance for available-for-sale securities accounted for as PCD assets	2	1
Reductions for securities sold during the period (realized)	6	5
Reductions for intent to sell or more likely than not will be required to sell the security before recovery of its amortized cost basis		1
Additional decreases to the allowance for credit losses on securities that had an allowance recorded in a previous period	(6)
Total allowance for credit losses	27	49
Corporate and Other Bonds [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member] | ASC 326 [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance		6
Asset-Backed [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	17	0
Additional decreases to the allowance for credit losses on securities that had an allowance recorded in a previous period	(1)
Total allowance for credit losses	$ 16	$ 0