Investments (Variable Interest Entities - Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Variable Interest Entity [Line Items]
Tax credits guaranteed by third parties that reduce maximum exposure to loss related to other invested assets	$ 151		$ 179
Variable Interest Entity, Financial or Other Support, Amount	0	$ 0
Consolidated Entities
Variable Interest Entity [Line Items]
Variable interest, maximum exposure to loss in consolidated securitization entities	$ 98		$ 105