Guarantee Arrangements and Pledged Assets and Collateral - Trend in Repurchase Demands Received on Loans Sold to GSEs and Other Third Parties by Loan Origination Vintage (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Commitments and Contingencies Disclosure [Abstract]
Pre- 2004	$ 1		$ 2		$ 3		$ 3
2004	2		7		11		11
2005	3		9		7		14
2006	11		29		26		45
2007	25		76		61		120
2008	13		52		35		78
Post 2008	5		6		10		10
Total repurchase demands received	$ 60	[1]	$ 181	[1]	$ 153	[1]	$ 281	[1]

[1] Includes repurchase demands on loans sourced from our legacy broker channel of $44 million and $151 million for the three months ended June 30, 2013 and 2012, respectively, and $120 million and $233 million for the six months ended June 30, 2013 and 2012, respectively.