Investments (Components of other-than-temporary impairment losses recognized in earnings) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Impairment losses recognized in earnings	$ 6	$ 92
Corporate and other bonds
Debt Securities, Available-for-sale [Line Items]
Impairment losses recognized in earnings	7	91
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Impairment losses recognized in earnings	$ (1)	$ 1