Receivables Held for Sale - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012 REO [Member]	Dec. 31, 2012 Short Sales [Member]	Jun. 30, 2012 First Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Unpaid principal balance				$ 8,100,000,000
Net realizable value of assets				4,600,000,000
Period of receivables sold in multiple transactions	2 years
Real estate secured receivables held for sale through short sale or transfer to REO		168,000,000
Reversed portion towards carrying value of assets held for sale		50,000,000	20,000,000
Short sale on real estate secured receivables			$ 96,000,000