Investments - Realized Gains (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Investments [Abstract]
Proceeds from sales	$ 1,419	$ 1,273	$ 2,142	$ 2,762
Gross realized capital gains	23	37	43	72
Gross realized capital losses	$ 21	$ 2	$ 56	$ 4