Expected Loss to be Paid - Components of Development and Accretion Amounts of Estimated Recoveries (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Expected Losses [Abstract]
Estimated increase (decrease) in defaults that will result in additional (lower) breaches(1)		$ 0	$ 17	$ 0	$ 27
Inclusion or removal of deals with breaches of R&W during period	[1]	3	(11)	(49)	(11)
Change in recovery assumptions		0	0	0	0
Settlements and anticipated settlements		0	10	0	45
Accretion of discount on balance		1	3	2	6
Total		$ 4	$ 19	$ (47)	$ 67

[1] The negative R&W development is offset by higher anticipated cash flows in the covered transactions that were related to a third party settlement.