Loans payable (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended							12 Months Ended
	Nov. 30, 2019	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Loans payable
Loans from FFG		$ 7,305				$ 8,316			$ 7,305	$ 8,316
Unamortized debt discount		(2,586)				(3,924)			(2,586)	(3,924)
Total Loans payable, net		4,719				4,392			4,719	4,392
Revenue		3,618	$ 2,038	$ 4,051	$ 2,235	5,080	$ 1,900	$ 649	11,942	7,629
Unearned income (current)		3,591				6,619			3,591	6,619
unearned income (non-current)		72				1,663			72	1,663
Unamortized debt discount		2,600				3,900			2,600	3,900
Interest expense									900	800	$ 600
Amortization of debt discount									800	700	500
Principal payment									$ 842	0
Estimated market rate									20.00%
Threshold for change in estimated market rate									0.10
Scheduled early repayment	$ 3,300
Adjustment
Loans payable
Deferred income reduced	$ 300
Grant
Loans payable
Revenue									$ 800	700	500
Unearned income (current)		700				800			700	800	700
unearned income (non-current)		$ 1,900				$ 3,000			$ 1,900	$ 3,000	$ 3,800
Minimum
Loans payable
Interest rate (as a percent)		0.75%							0.75%
Maximum
Loans payable
Interest rate (as a percent)		1.00%							1.00%