Commitments and Contingencies - Torreya Agreement (Details) - Advisory services - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020
Other Commitments [Line Items]
Additional consultant fee payable, percentage of perpetuity	3.375%
Sponsor fees	$ 935	$ 643

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=123367319&loc=SL114868664-224227

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