Investments - Realized capital gains and losses by asset type (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Realized capital gains and losses by asset type
Realized capital gains (losses)	$ 426	$ (162)
Fixed income securities
Realized capital gains and losses by asset type
Realized capital gains (losses)	183	374
Equity securities
Realized capital gains and losses by asset type
Realized capital gains (losses)	164	(510)
Mortgage loans
Realized capital gains and losses by asset type
Realized capital gains (losses)	6	(10)
Limited partnership interests
Realized capital gains and losses by asset type
Realized capital gains (losses)	4	(86)
Derivatives
Realized capital gains and losses by asset type
Realized capital gains (losses)	11	78
Other
Realized capital gains and losses by asset type
Realized capital gains (losses)	$ 58	$ (8)