Investments - Summary of Selected Financial Information for JCP Fund V (Details) - JCP Fund V - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	6 Months Ended
Jan. 31, 2018	May 31, 2018	Dec. 31, 2017	May 31, 2017	Mar. 31, 2017	Dec. 31, 2016	May 31, 2018	May 31, 2017
Schedule of Equity Method Investments [Line Items]
Net gains (losses) from our investments in JCP Fund V		$ 3,000		$ (7,200)			$ 9,800	$ (7,900)
Net increase (decrease) in net assets resulting from operations	$ 8,463		$ 19,712		$ (19,552)	$ (2,294)

Amount of unrealized gain (loss) recognized in the income statement on unsold other securities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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