Consolidated Securitization Vehicles and Other Variable Interest Entities - Effect on Consolidated Financial Condition (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Assets:
Non-Agency RMBS, at fair value	$ 2,593,422	$ 2,851,316
Loans held for investment, at fair value	13,246,521	13,678,263
Accrued interest receivable	106,877	100,789
Other Assets	106,594	114,391
Liabilities:
Securitized debt, collateralized by Non-Agency RMBS	179,742	205,780
Securitized debt at fair value, collateralized by loans held for investment	9,340,368	9,388,657
Accrued interest payable	71,405	61,888
Other liabilities	13,818	17,191
Variable Interest Entities, Primary Beneficiary
Assets:
Non-Agency RMBS, at fair value	1,280,378	1,579,793
Loans held for investment, at fair value	13,045,302	13,263,338
Accrued interest receivable	75,390	75,489
Other Assets	54,708	68,844
Liabilities:
Securitized debt, collateralized by Non-Agency RMBS	179,742	205,780
Securitized debt at fair value, collateralized by loans held for investment	9,340,368	9,388,657
Accrued interest payable	35,754	33,870
Other liabilities	$ 3,285	$ 3,513