Investments - Net appreciation (decline) recognized in net income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Realized capital gains and losses by asset type
Net appreciation (decline) recognized in net income	$ 336	$ 302	$ (154)	$ 747
Equity securities
Realized capital gains and losses by asset type
Net appreciation (decline) recognized in net income	390	207	(45)	688
Limited partnership interests
Realized capital gains and losses by asset type
Net appreciation (decline) recognized in net income	$ (54)	$ 95	$ (109)	$ 59