Investments (Variable Interest Entities - Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 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	$ 170		$ 179
Financial or other support to investees designated as VIEs	0	$ 0
Consolidated Entities
Variable Interest Entity [Line Items]
Variable interest, maximum exposure to loss in consolidated securitization entities	$ 107		$ 105
Long-term debt held by consolidated securitization entities, percentage range minimum	2.25%	2.25%
Long-term debt held by consolidated securitization entities, percentage range maximum	5.57%	5.57%
Interest expense on long-term debt held by consolidated securitization entities	$ 1	$ 1