Warrant Liabilities - Summary of outstanding warrants (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Jul. 01, 2020	May 29, 2020	Oct. 22, 2015
Class of Warrant or Right [Line Items]
Outstanding warrants (in shares)	22,510,038		22,510,038
Class of Warrant or Right [Roll Forward]
Beginning balance	$ 15,389
Fair value adjustments	(9,493)	$ 0
Ending balance	$ 5,897
5-Year Private Warrants
Class of Warrant or Right [Line Items]
Outstanding warrants (in shares)	9,888,415		9,888,415
Class of Warrant or Right [Roll Forward]
Beginning balance	$ 15,326
Fair value adjustments	(9,459)
Ending balance	$ 5,867
Seller Warrants
Class of Warrant or Right [Line Items]
Outstanding warrants (in shares)	12,621,623		12,621,623	12,700,000	12,700,000	12,721,623
Class of Warrant or Right [Roll Forward]
Beginning balance	$ 63
Fair value adjustments	(34)
Ending balance	$ 28