Variable Interest Entities - Summary of Assets and Liabilities of Consolidated CLO and Single Asset Securitization VIE (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Assets:
Assets	$ 1,500,000	$ 1,500,000
VIE [Member]
Assets:
Assets	1,504,669	1,505,440
Liabilities:
Liabilities	1,289,361	1,287,626
VIE [Member] | Loans Receivable [Member]
Assets:
Assets	1,467,626	1,500,000
VIE [Member] | Other Assets [Member]
Assets:
Assets	37,043	5,440
VIE [Member] | Securitized Debt Obligations, Net [Member]
Liabilities:
Liabilities	1,287,364	1,285,471
VIE [Member] | Other Liabilities [Member]
Liabilities:
Liabilities	$ 1,997	$ 2,155