Stock-based compensation - Summary of Stock Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share based compensation	$ 12,456	$ 14,142	$ 8,206
Cost of goods sold
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share based compensation	2,244	2,596	1,098
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share based compensation	3,138	3,570	2,491
Sales and marketing
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share based compensation	2,411	3,248	1,697
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share based compensation	$ 4,663	$ 4,728	$ 2,920