Intangible assets, net - Summary of Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 18,114		$ 17,921
Accumulated amortization	(8,570)		(7,727)
Intangible assets, net	9,544	$ 10,194	10,194
Patent costs
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	5,484		5,291
Developed technology
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	9,800		9,800
In-process research & development
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	1,580		1,580
Customer base
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	700		700
Trade names and trademarks
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 550		$ 550