Components of Mortgage Banking Activities, Net (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Income from MSRs, net:
MSRs	$ 460		$ (650)		$ 9,629		$ (1,194)
Sequoia IO securities	(1,866)		(4,427)		36,399		(9,101)
Risk management derivatives	442		(2,385)		51,009		(8,784)
Net market valuation adjustments	(8,597)		7,514		82,524		(4,087)
Mortgage Banking Activities, Net	(5,944)		12,303		98,608		13,642
Residential Loans at Fair Value
Income from MSRs, net:
Loans, at fair value	(10,804)		14,976		(17,339)		14,992
Commercial Loans at Fair Value
Income from MSRs, net:
Loans, at fair value	3,171				2,826
Mortgage Banking Activities
Income from MSRs, net:
Income	2,991		231		5,785		368
Late charges	17		2		35		3
Cost of sub-servicer	(355)		(55)		(767)		(89)
Income from MSRs, net:	2,653		178		5,053		282
MSRs	460		(650)		9,628		(1,194)
Sequoia IO securities	(1,866)		(4,427)		36,399		(9,101)
Risk management derivatives	442	[1]	(2,385)	[1]	51,010	[1]	(8,784)	[1]
Net market valuation adjustments	(8,597)		7,514		82,524		(4,087)
Mortgage Banking Activities, Net	(5,944)		12,303		98,608		13,642
Mortgage Banking Activities | Residential Loans at Fair Value
Income from MSRs, net:
Loans, at fair value	(10,804)		14,976		(17,339)		14,992
Mortgage Banking Activities | Commercial Loans at Fair Value
Income from MSRs, net:
Loans, at fair value	3,171				2,826
Mortgage Banking Activities | Residential Loans
Income from MSRs, net:
Net gains on loan sales			4,611				17,447
Mortgage Banking Activities | Commercial Loans
Income from MSRs, net:
Net gains on commercial loan originations					40
Net gains on loan sales					$ 10,991

[1] Represents market valuations of derivatives that are used to manage risks associated with our accumulation of residential and commercial loans.