Investments Investments - Rollforward of credit loss allowance for mortgage loans (Details) - Mortgage loans - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ (85)		$ (3)
Net increases related to credit losses	(1)	$ 0	(41)	$ 0
Ending balance	$ (86)		(86)
Cumulative effect of change in accounting principle
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Roll Forward]
Beginning balance			$ (42)