Residential Loans at Amortized Cost, Net - Activity in Allowance for Loan Losses on Residential Loans, Net (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of the year	$ 14,320,000	$ 20,435,000	$ 13,824,000
Provision for loan losses	1,491,000	1,229,000	13,352,000
Charge-offs, net of recoveries	(5,778,000)	(7,344,000)	(6,741,000)
Balance at end of the year	10,033,000	14,320,000	20,435,000
Charge-offs recognized upon acquisition of real estate in satisfaction of residential loans	$ 4,300,000	$ 7,200,000	$ 5,900,000