Investments (Allowance on available-for-sale securities with credit impairments and PCD assets activity) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Allowance for credit losses:
Balance, beginning of period	$ 16	$ 1
Additions to the allowance for credit losses:
Securities for which credit losses were not previously recorded	0	0
Available-for-sale securities accounted for as PCD assets	0	9
Reductions to the allowance for credit losses:
Securities sold during the period (realized)	0	6
Intent to sell or more likely than not will be required to sell the security before recovery of its amortized cost basis	1	3
Write-offs charged against the allowance	0	0
Recoveries of amounts previously written off	0	0
Additional increases or (decreases) to the allowance for credit losses on securities that had an allowance recorded in a previous period	5	1
Balance, end of period	20	2
Corporate and other bonds
Allowance for credit losses:
Balance, beginning of period	4	0
Additions to the allowance for credit losses:
Securities for which credit losses were not previously recorded	0	0
Available-for-sale securities accounted for as PCD assets	0	9
Reductions to the allowance for credit losses:
Securities sold during the period (realized)	0	6
Intent to sell or more likely than not will be required to sell the security before recovery of its amortized cost basis	1	3
Write-offs charged against the allowance	0	0
Recoveries of amounts previously written off	0	0
Additional increases or (decreases) to the allowance for credit losses on securities that had an allowance recorded in a previous period	0	1
Balance, end of period	3	1
Asset-backed
Allowance for credit losses:
Balance, beginning of period	12	1
Additions to the allowance for credit losses:
Securities for which credit losses were not previously recorded	0	0
Available-for-sale securities accounted for as PCD assets	0	0
Reductions to the allowance for credit losses:
Securities sold during the period (realized)	0	0
Intent to sell or more likely than not will be required to sell the security before recovery of its amortized cost basis	0	0
Write-offs charged against the allowance	0	0
Recoveries of amounts previously written off	0	0
Additional increases or (decreases) to the allowance for credit losses on securities that had an allowance recorded in a previous period	5	0
Balance, end of period	$ 17	$ 1