Investments - Realized capital gains and losses by asset type (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Realized capital gains and losses by asset type
Realized capital gains (losses)	$ 287	$ 440	$ 713	$ 278
Fixed income securities
Realized capital gains and losses by asset type
Realized capital gains (losses)	86	168	269	542
Equity securities
Realized capital gains and losses by asset type
Realized capital gains (losses)	152	248	316	(262)
Mortgage loans
Realized capital gains and losses by asset type
Realized capital gains (losses)	13	7	19	(3)
Limited partnership interests
Realized capital gains and losses by asset type
Realized capital gains (losses)	12	15	16	(71)
Derivatives
Realized capital gains and losses by asset type
Realized capital gains (losses)	(3)	14	8	92
Other
Realized capital gains and losses by asset type
Realized capital gains (losses)	$ 27	$ (12)	$ 85	$ (20)