Investments - OTTI losses by asset type (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Realized capital gains and losses by asset type
Total credit losses by asset type	$ (11)	$ (15)	$ (89)	$ (29)
Commitments to fund commercial mortgage loans, bank loans and agent loans	1	0	0	0
Total	(10)	(15)	(89)	(29)
Municipal
Realized capital gains and losses by asset type
Total	(3)	0	(3)	0
Corporate
Realized capital gains and losses by asset type
Total	0	(7)	(1)	(7)
ABS
Realized capital gains and losses by asset type
Total	(2)	(2)	(2)	(3)
MBS
Realized capital gains and losses by asset type
Total	1	0	(2)	(1)
Fixed income securities
Realized capital gains and losses by asset type
Total	(4)	(9)	(8)	(11)
Mortgage loans
Realized capital gains and losses by asset type
Net increases related to credit losses	(1)	0	(41)	0
Limited partnership interests
Realized capital gains and losses by asset type
Limited partnership interests	(3)	(2)	(10)	(3)
Bank loans, net
Realized capital gains and losses by asset type
Net increases related to credit losses	$ (3)	$ (4)	$ (30)	$ (15)