Property and Equipment - Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 5,782	$ 6,546	$ 5,882
Cost of sales
Property, Plant and Equipment [Line Items]
Depreciation expense	2,022	1,965	1,757
Selling, general and administrative expenses
Property, Plant and Equipment [Line Items]
Depreciation expense	3,416	4,223	3,760
Research and development expenses
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 344	$ 358	$ 365