Summary of Activity in Allowance for Losses on Residential Loans (Detail) (Residential Loans, USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Residential Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	$ 23,150	$ 55,449	$ 28,504	$ 66,881
Charge-offs, net	(818)	(2,514)	(3,363)	(7,653)
Provision for (reversal of) provision for loan losses	883	813	(1,926)	(902)
Deconsolidation adjustment				(4,578)
Balance at End of Period	$ 23,215	$ 53,748	$ 23,215	$ 53,748