Guarantee Arrangements and Pledged Assets and Collateral - Outstanding Repurchase Demands Received From GSEs and Other Third Parties (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Commitments and Contingencies Disclosure [Abstract]
GSEs	$ 64		$ 86
Others	3		3
Total	$ 67	[1]	$ 89	[1]

[1] Includes repurchase demands on loans sourced from our legacy broker channel of $55 million and $65 million at September 30, 2013 and December 31, 2012, respectively.