Commitments and Contingencies - Founder Royalty arrangements (Details) - Founders and initial investors - Royalty Agreements $ in Thousands	6 Months Ended
Jun. 30, 2020 USD ($)
Founder Royalty arrangements
Period of royalty payments agreed under arrangement	10 years
Royalties paid	$ 0

The amount of cash paid for royalties during the current period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3536-108585

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