Residential Mortgage Loans Held-For-Securitization - Carrying Value for Residential Mortgage Loans (Detail) - USD ($) $ in Thousands		Sep. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Carrying value	[1]	$ 483,648		$ 549,016
Residential Mortgage Backed Securities
Variable Interest Entity [Line Items]
Principal balance		125,565		11,281
Unamortized premium, net of discount		3,449		379
Carrying value		$ 129,014	$ 121,715	$ 11,660

[1] The consolidated balance sheets include assets of consolidated variable interest entities, or 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, 2019 and December 31, 2018, total assets of the consolidated VIEs were $485 million and $551 million (including accrued interest receivable of $1.6 million and $1.8 million), respectively (which is recorded above in the line item entitled “Interest receivable”), and total liabilities were $476 million and $541 million (including accrued interest payable of $1.6 million and $1.7 million), respectively (which is recorded in the line item above entitled “Accrued interest payable”). Please refer to Note 5, “Variable Interest Entities,” for further discussion.