Consolidation - Beneficial Interests of Consolidated Investment Product (Detail) - Consolidated Investment Product [Member] $ in Thousands	Dec. 31, 2016 USD ($)
Variable Interest Entity [Line Items]
Subordinated notes	$ 25,668
Accrued investment management fees	341
Total Beneficial Interests	$ 26,009

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_VariableInterestEntityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration