Variable Interest Entities ("VIE's") (Consolidated Variable Interest Entity Settlement Payments and Mark-to-Market Adjustments) (Details) - Derivative Instruments Not Designated and Not Qualifying as Hedging Instruments - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Consolidated Variable Interest Entity Settlement Payments And Mark To Market Adjustments [Line Items]
Gains (losses) for consolidated variable interest entities	[1]	$ (1)	$ 2	$ 5	$ 10
Credit default swaps [Member]
Consolidated Variable Interest Entity Settlement Payments And Mark To Market Adjustments [Line Items]
Gains (losses) for consolidated variable interest entities		(1)	2	5	10
Contingent forwards
Consolidated Variable Interest Entity Settlement Payments And Mark To Market Adjustments [Line Items]
Gains (losses) for consolidated variable interest entities

[1] Reported in realized gain (loss) on our Consolidated Statements of Comprehensive Income (Loss).