Investments - Realized capital gains and 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
Realized capital gains (losses)	$ (462)	$ 662
Fixed income securities
Realized capital gains and losses by asset type
Realized capital gains (losses)	375	64
Equity securities
Realized capital gains and losses by asset type
Realized capital gains (losses)	(750)	553
Mortgage loans
Realized capital gains and losses by asset type
Realized capital gains (losses)	(41)	0
Limited partnership interests
Realized capital gains and losses by asset type
Realized capital gains (losses)	(116)	72
Derivatives
Realized capital gains and losses by asset type
Realized capital gains (losses)	88	(46)
Other
Realized capital gains and losses by asset type
Realized capital gains (losses)	$ (18)	$ 19