Investments (Components of other-than-temporary impairment losses recognized in earnings) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Debt Securities, Available-for-sale [Line Items]
Impairment losses (gains) recognized in earnings	$ 11	$ 5	$ 16	$ 108
Corporate and other bonds
Debt Securities, Available-for-sale [Line Items]
Impairment losses (gains) recognized in earnings	0	4	5	94
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Impairment losses (gains) recognized in earnings	$ 11	$ 1	$ 11	$ 14