Investments - Realized capital gains and 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
Realized capital gains (losses)	$ 704	$ 324	$ 242	$ 986
Fixed income securities
Realized capital gains and losses by asset type
Realized capital gains (losses)	187	79	562	143
Equity securities
Realized capital gains and losses by asset type
Realized capital gains (losses)	480	178	(270)	731
Mortgage loans
Realized capital gains and losses by asset type
Realized capital gains (losses)	0	0	(41)	0
Limited partnership interests
Realized capital gains and losses by asset type
Realized capital gains (losses)	33	21	(83)	93
Derivatives
Realized capital gains and losses by asset type
Realized capital gains (losses)	18	22	106	(24)
Other
Realized capital gains and losses by asset type
Realized capital gains (losses)	$ (14)	$ 24	$ (32)	$ 43