Investments - Realized capital gains and losses by asset type (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Realized capital gains and losses by asset type
Realized capital gains (losses)	$ 105	$ 319	$ 818	$ 597
Fixed income securities
Realized capital gains and losses by asset type
Realized capital gains (losses)	86	216	355	758
Equity securities
Realized capital gains and losses by asset type
Realized capital gains (losses)	6	114	322	(148)
Mortgage loans
Realized capital gains and losses by asset type
Realized capital gains (losses)	0	1	19	(2)
Limited partnership interests
Realized capital gains and losses by asset type
Realized capital gains (losses)	(15)	15	1	(56)
Derivatives
Realized capital gains and losses by asset type
Realized capital gains (losses)	46	(30)	54	62
Other
Realized capital gains and losses by asset type
Realized capital gains (losses)	$ (18)	$ 3	$ 67	$ (17)