Investments (Variable Interest Entities - Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 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	$ 162		$ 162		$ 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	106		106		$ 105
Interest expense on long-term debt held by consolidated securitization entities	$ 2	$ 1	$ 3	$ 2
Minimum | Consolidated Entities
Variable Interest Entity [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	2.25%		2.25%		2.25%
Maximum | Consolidated Entities
Variable Interest Entity [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	5.57%		5.57%		5.57%