Servicing of Residential Loans - Significant Judgment and Key Economic Assumptions Used in Estimation of Fair Value of Servicing Rights (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011
Servicing Assets at Fair Value [Line Items]
Servicing rights at amortized cost	$ 193,833	$ 205,042	$ 216,330
Inputs and assumptions:
Servicing rights at fair value	880,950		0
Conditional default rate	4.02%
Servicing Rights Carried at Amortized Cost [Member] | Forward Loans [Member]
Servicing Assets at Fair Value [Line Items]
Servicing rights at amortized cost	180,002	190,336	200,742	224,203	237,414	250,329
Inputs and assumptions:
Weighted-average remaining life in years	5 years 2 months 12 days
Weighted-average stated customer interest rate on underlying collateral	7.78%
Weighted-average discount rate	11.67%
Conditional prepayment rate	7.31%
Conditional default rate	4.54%
Servicing Rights Carried at Amortized Cost [Member] | Reverse Loans [Member]
Servicing Assets at Fair Value [Line Items]
Servicing rights at amortized cost	13,831	14,706	15,588
Inputs and assumptions:
Weighted-average remaining life in years	3 years 1 month 6 days
Weighted-average stated customer interest rate on underlying collateral	3.19%
Weighted-average discount rate	18.00%
Conditional repayment rate	24.90%
Servicing Rights Carried at Fair Value [Member]
Inputs and assumptions:
Servicing rights at fair value	$ 880,950	$ 759,683	$ 26,382
Weighted-average remaining life in years	5 years 4 months 24 days
Weighted-average stated customer interest rate on underlying collateral	5.04%
Weighted-average discount rate	9.37%
Conditional prepayment rate	9.31%
Conditional default rate	4.02%