Investments (Components of other-than-temporary impairment losses recognized in earnings) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Debt Securities, Available-for-sale [Line Items]
Impairment losses (gains) recognized in earnings	$ (1)	$ 11	$ 5	$ 103
Corporate and other bonds
Debt Securities, Available-for-sale [Line Items]
Impairment losses (gains) recognized in earnings	(2)	(1)	5	90
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Impairment losses (gains) recognized in earnings	$ 1	$ 12	$ 0	$ 13