Investments - Rollforward of credit loss allowance for mortgage loans (Details) - Mortgage loans - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Credit Losses on Fixed Income Securities
Beginning balance	$ (45)	$ (85)	$ (67)	$ (3)
Net decreases (increases) related to credit losses	15	(1)	37	(41)
Write-offs	0	0	0	0
Ending balance	(30)	(86)	(30)	(86)
Discontinued Operations, Held-for-sale
Credit Losses on Fixed Income Securities
Ending balance	(23)	(75)	(23)	(75)
Cumulative effect of change in accounting principle
Credit Losses on Fixed Income Securities
Beginning balance	$ 0	$ 0	$ 0	$ (42)