Investments - OTTI losses by asset type (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Realized capital gains and losses by asset type
Total credit losses by asset type	$ 78	$ 14
Commitments to fund commercial mortgage loans, bank loans and agent loans	(1)	0
Allowance for Credit Loss, Credit Loss Recognized In Net Income	79	14
Corporate
Realized capital gains and losses by asset type
Total fixed income securities	(1)	0
ABS
Realized capital gains and losses by asset type
Total fixed income securities	0	(1)
MBS
Realized capital gains and losses by asset type
Total fixed income securities	(3)	(1)
Fixed income securities
Realized capital gains and losses by asset type
Total fixed income securities	(4)	(2)
Mortgage loans
Realized capital gains and losses by asset type
Net (increases) decreases related to credit losses	40	0
Limited partnership interests
Realized capital gains and losses by asset type
Limited partnership interests	7	1
Bank loans, net
Realized capital gains and losses by asset type
Net (increases) decreases related to credit losses	$ 27	$ 11