Investments and Fair Value Disclosures - Schedule of Net Unrealized Gains (Losses) on Company's Level III Assets and Liabilities (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Management company related \| CLOs
Fair Value, Investments Measured On Recurring Basis [Line Items]
Unrealized gains (losses) on Level III assets and liabilities held as of the balance sheet date	$ (2,877)	$ (9,998)
Funds \| Bank Debt
Fair Value, Investments Measured On Recurring Basis [Line Items]
Unrealized gains (losses) on Level III assets and liabilities held as of the balance sheet date	$ 0	$ (2,160)

Amount of unrealized gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3) and still held.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration