Investments (Net investment income summary) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Investment income on fixed maturities	$ 1,378	$ 1,353	$ 1,349
Net realized gains (losses)	(8)	10	46
Affordable housing partnerships	(98)	(58)	(100)
Other	97	154	108
Consolidated investment entities	94	137	106
Total net investment income	$ 1,463	$ 1,596	$ 1,509