Expected Loss to be Paid - Components of Development and Accretion Amounts of Estimated Recoveries (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Expected Losses [Abstract]
Estimated increase (decrease) in defaults that will result in additional (lower) breaches(1)	$ (52)	[1]	$ 0	[1]
Inclusion or removal of deals with breaches of R&W during period	0		0
Change in recovery assumptions	0		10
Settlements and anticipated settlements	0		35
Accretion of discount on balance	1		3
Total	$ (51)		$ 48

[1] (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.