Investments - Rollforward of credit loss allowance for fixed income securities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Credit Losses on Fixed Income Securities [Roll Forward]
Beginning balance		$ 0
Fixed income securities
Fixed income securities
Credit Losses on Fixed Income Securities [Roll Forward]
Beginning balance	$ (2)
Credit losses on securities for which credit losses not previously reported	(5)	(2)
Net decreases related to credit losses previously reported	1	0
Reduction of allowance related to sales	0	0
Write-offs	0	0
Ending balance	(6)	(2)
Fixed income securities	6	2
Corporate
Credit Losses on Fixed Income Securities [Roll Forward]
Beginning balance	(1)
Ending balance	(6)	(1)
Fixed income securities	6	1
ABS
Credit Losses on Fixed Income Securities [Roll Forward]
Beginning balance	$ (1)
Ending balance		(1)
Fixed income securities		$ 1