Residential Loans at Amortized Cost, Net - Activity in Allowance for Loan Losses on Residential Loans, Net (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of the period	$ 10,033,000	$ 14,320,000
Allowance for Loan and Lease Losses, Adjustments, Net	1,642,000	(1,004,000)
Charge-offs, net of recoveries	(1,015,000)	(1,232,000)
Balance at end of the period	10,660,000	12,084,000
Charge-offs recognized upon acquisition of real estate in satisfaction of residential loans	$ 600,000	$ 1,100,000