Expected Losses to be Paid (Details 8) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Expected Losses [Abstract]
Inclusion of new deals with breaches of R&W during period	$ 6	$ (5)	$ 6	$ (5)
Change in recovery assumptions as the result of additional file review and recovery success	6	(10)	17	70
Estimated increase (decrease) in defaults that will result in additional breaches	(4)	58	(3)	(24)
Results of settlements	38	0	180	48
Accretion of discount on balance	5	3	8	8
Expected Future Recoveries for Breached Representations and Warranties Development and Accretion of Discount	$ 51	$ 46	$ 208	$ 97