Variable Interest Entities - Carrying Value for Residential Mortgage Loans (Detail) - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Carrying value	[1]	$ 690,958	$ 0
Variable Interest Entity Primary Beneficiary
Variable Interest Entity [Line Items]
Principal balance		680,919
Paydowns receivable		83
Unamortized premium net of discount		(10,096)
Allowance for loan losses		(140)
Carrying value		$ 690,958

[1] The consolidated balance sheets include assets of consolidated variable interest entities (“VIEs”) that can only be used to settle obligations and liabilities of the VIEs for which creditors do not have recourse to the Company. At September 30, 2015 and December 31, 2014, total assets of the consolidated VIEs were $693 million and $0, respectively, and total liabilities were $642 million and $0, respectively. Please refer to Note 4, “Variable Interest Entities,” for further discussion.