Stock Compensation - Components of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 2,714	$ 2,897	$ 2,617
Cost of sales
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	142	191	191
Selling, general, and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	2,384	2,413	2,127
Research and development expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 188	$ 293	$ 299