Servicing of Residential Loans - Summary of Activity in Carrying Value of Servicing Rights (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Servicing Asset at Amortized Cost [Line Items]
Balance at beginning of period	$ 205,042		$ 216,330
Purchases			36
Amortization	(11,209)	(13,211)	(22,533)	(26,126)
Impairment
Balance at end of period	193,833		193,833
Servicing Rights Carried at Amortized Cost [Member] | Forward Loans [Member]
Servicing Asset at Amortized Cost [Line Items]
Balance at beginning of period	190,336	237,414	200,742	250,329
Purchases
Amortization	(10,334)	(13,211)	(20,740)	(26,126)
Impairment
Balance at end of period	180,002	224,203	180,002	224,203
Servicing Rights Carried at Amortized Cost [Member] | Reverse Loans [Member]
Servicing Asset at Amortized Cost [Line Items]
Balance at beginning of period	14,706		15,588
Purchases			36
Amortization	(875)		(1,793)
Impairment
Balance at end of period	$ 13,831		$ 13,831