Investments - Realized capital gains and losses by asset type (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Realized capital gains and losses by asset type
Realized capital gains and losses	$ 662	$ (134)
Fixed income securities
Realized capital gains and losses by asset type
Realized capital gains and losses	64	(43)
Equity securities
Realized capital gains and losses by asset type
Realized capital gains and losses	553	(93)
Limited partnership interests
Realized capital gains and losses by asset type
Realized capital gains and losses	72	10
Derivatives
Realized capital gains and losses by asset type
Realized capital gains and losses	(46)	(8)
Other
Realized capital gains and losses by asset type
Realized capital gains and losses	$ 19	$ 0