Servicing of Residential Loans - Schedule of Fair Value Assumption, Date of Securitization or Asset-backed Financing Arrangement, Transferor's Continuing Involvement, Servicing Assets or Liabilities (Detail)	3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013
Fair Value Assumption, Date of Securitization or Asset-backed Financing Arrangement, Transferor's Continuing Involvement, Servicing Assets or Liabilities [Line Items]
Weighted-average discount rates		9.40%
Conditional prepayment rates		8.16%
Conditional default rates		3.21%
Minimum [Member]
Fair Value Assumption, Date of Securitization or Asset-backed Financing Arrangement, Transferor's Continuing Involvement, Servicing Assets or Liabilities [Line Items]
Weighted-average life in years	8 years 9 months 18 days	6 years 1 month 6 days
Weighted-average stated customer interest rate on underlying collateral	3.73%	3.73%
Weighted-average discount rates	9.50%	9.50%
Conditional prepayment rates	4.78%	3.00%
Conditional default rates	0.69%	0.50%
Maximum [Member]
Fair Value Assumption, Date of Securitization or Asset-backed Financing Arrangement, Transferor's Continuing Involvement, Servicing Assets or Liabilities [Line Items]
Weighted-average life in years	9 years 6 months	9 years 7 months 6 days
Weighted-average stated customer interest rate on underlying collateral	4.32%	4.32%
Weighted-average discount rates	9.72%	12.30%
Conditional prepayment rates	6.09%	8.10%
Conditional default rates	0.96%	2.00%