Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue
Total revenue	$ 19,593	$ 19,100	$ 40,237	$ 38,756
Cost of revenue	9,971	9,989	20,784	20,858
Gross profit	9,622	9,111	19,453	17,898
Operating expenses
Sales and marketing	6,897	9,809	15,078	20,220
Research and development	3,328	4,850	6,240	9,544
General and administrative	5,289	5,802	10,618	11,942
Total operating expenses	15,514	20,461	31,936	41,706
Loss from operations	(5,892)	(11,350)	(12,483)	(23,808)
Other income and expenses
Interest income	91	171	198	311
Interest expense	(1,337)	(766)	(1,790)	(1,501)
Foreign currency exchange transaction (loss) income	398	(2,098)	(255)	(1,013)
Total other (expenses) income, net	(848)	(2,693)	(1,847)	(2,203)
Loss before income taxes	(6,740)	(14,043)	(14,330)	(26,011)
Income tax provision	23	14	14	47
Net loss	$ (6,763)	$ (14,057)	$ (14,344)	$ (26,058)
Net loss per share - basic and diluted (in dollars per share)	$ (0.11)	$ (0.24)	$ (0.23)	$ (0.46)
Weighted average common shares outstanding - basic and diluted (in shares)	63,333,737	59,763,259	63,092,874	57,208,114
Product
Revenue
Total revenue	$ 19,337	$ 18,908	$ 39,806	$ 38,391
Royalty
Revenue
Total revenue	$ 256	$ 192	$ 431	$ 365