Investments (Consolidated Variable Interest Entities - Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Tax credits guaranteed by third parties that reduce maximum exposure to loss related to other invested assets	$ 150	$ 179
Financial or other support to investees designated as VIEs	0	0	$ 0
Consolidated Entities
Variable Interest Entity [Line Items]
Variable interest, maximum exposure to loss in consolidated securitization entities	$ 95	$ 105