Commitments - Torreya Agreement (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Other Commitments [Line Items]
Additional consultant fee payable, percentage of perpetuity in excess of $3 million	3.375%
Advisory Services
Other Commitments [Line Items]
Sponsor fees	$ 129	$ 66

Fees paid to advisors who provide certain management support and administrative oversight services including the organization and sale of stock, investment funds, limited partnerships and mutual funds.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

Name:	us-gaap_SponsorFees
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration