Investments - Rollforward of credit loss allowance for mortgage loans (Details) - Mortgage loans - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Credit Losses on Fixed Income Securities
Beginning balance	$ (30)	$ (86)	$ (67)	$ (3)
Net (increases) decreases related to credit losses	2	1	39	(40)
Write-offs	0	0	0	0
Ending balance	(28)	(85)	(28)	(85)
Discontinued Operations, Held-for-sale
Credit Losses on Fixed Income Securities
Ending balance	(21)	(74)	(21)	(74)
Cumulative effect of change in accounting principle
Credit Losses on Fixed Income Securities
Beginning balance	$ 0	$ 0	$ 0	$ (42)