Investments - Allowance for credit losses (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Allowance for Loan and Lease Losses [Roll Forward]
Balance as of January 1, 2022	$ 48	$ 14
Credit losses on securities for which credit losses were not previously recorded	20	36
Initial allowance for credit losses recognized on financial assets accounted for as PCD	0	0
Reductions for securities sold during the period	(37)	0
Reductions for intent to sell or more likely than not will be required to sell securities prior to recovery of amortized cost	0	0
Increase (decrease) on securities with allowance recorded in previous period	2	(2)
Write-offs	0	0
Recoveries of amounts previously written-off	0	0
Balance at June 30, 2022	33	48
Residential mortgage-backed
Allowance for Loan and Lease Losses [Roll Forward]
Balance as of January 1, 2022	1	1
Credit losses on securities for which credit losses were not previously recorded	0	1
Initial allowance for credit losses recognized on financial assets accounted for as PCD	0	0
Reductions for securities sold during the period	0	0
Reductions for intent to sell or more likely than not will be required to sell securities prior to recovery of amortized cost	0	0
Increase (decrease) on securities with allowance recorded in previous period	(1)	(1)
Write-offs	0	0
Recoveries of amounts previously written-off	0	0
Balance at June 30, 2022	0	1
Commercial mortgage-backed
Allowance for Loan and Lease Losses [Roll Forward]
Balance as of January 1, 2022	0	0
Credit losses on securities for which credit losses were not previously recorded	1	0
Initial allowance for credit losses recognized on financial assets accounted for as PCD	0	0
Reductions for securities sold during the period	0	0
Reductions for intent to sell or more likely than not will be required to sell securities prior to recovery of amortized cost	0	0
Increase (decrease) on securities with allowance recorded in previous period	0	0
Write-offs	0	0
Recoveries of amounts previously written-off	0	0
Balance at June 30, 2022	1	0
Foreign corporate private securities
Allowance for Loan and Lease Losses [Roll Forward]
Balance as of January 1, 2022	47	11
Credit losses on securities for which credit losses were not previously recorded	0	35
Initial allowance for credit losses recognized on financial assets accounted for as PCD	0	0
Reductions for securities sold during the period	(37)	0
Reductions for intent to sell or more likely than not will be required to sell securities prior to recovery of amortized cost	0	0
Increase (decrease) on securities with allowance recorded in previous period	3	1
Write-offs	0	0
Recoveries of amounts previously written-off	0	0
Balance at June 30, 2022	13	47
Other Asset-backed Securities [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance as of January 1, 2022	0	2
Credit losses on securities for which credit losses were not previously recorded	0	0
Initial allowance for credit losses recognized on financial assets accounted for as PCD	0	0
Reductions for securities sold during the period	0	0
Reductions for intent to sell or more likely than not will be required to sell securities prior to recovery of amortized cost	0	0
Increase (decrease) on securities with allowance recorded in previous period	0	(2)
Write-offs	0	0
Recoveries of amounts previously written-off	0	0
Balance at June 30, 2022	0	0
Foreign corporate public securities and foreign governments
Allowance for Loan and Lease Losses [Roll Forward]
Balance as of January 1, 2022	0
Credit losses on securities for which credit losses were not previously recorded	18
Initial allowance for credit losses recognized on financial assets accounted for as PCD	0
Reductions for securities sold during the period	0
Reductions for intent to sell or more likely than not will be required to sell securities prior to recovery of amortized cost	0
Increase (decrease) on securities with allowance recorded in previous period	0
Write-offs	0
Recoveries of amounts previously written-off	0
Balance at June 30, 2022	18	0
U.S. corporate private securities
Allowance for Loan and Lease Losses [Roll Forward]
Balance as of January 1, 2022	0
Credit losses on securities for which credit losses were not previously recorded	1
Initial allowance for credit losses recognized on financial assets accounted for as PCD	0
Reductions for securities sold during the period	0
Reductions for intent to sell or more likely than not will be required to sell securities prior to recovery of amortized cost	0
Increase (decrease) on securities with allowance recorded in previous period	0
Write-offs	0
Recoveries of amounts previously written-off	0
Balance at June 30, 2022	$ 1	$ 0