Investments (Net investment income summary) (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Investment income on fixed maturities	$ 1,368	$ 1,403	$ 1,479
Net realized gains	6	4	37
Affordable housing partnerships	(44)	(18)	(25)
Other	91	68	93
Consolidated investment entities	155	231	157
Total net investment income	$ 1,576	$ 1,688	$ 1,741