Stock Option and Purchase Plans (Share-based compensation by COS & OPEX) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-Based Compensation Expense
Share-based compensation	$ 2,026	$ 3,285	$ 2,942
Total share-based compensation cost capitalized as part of cost of inventory	39	26	9
Cost of goods sold
Share-Based Compensation Expense
Share-based compensation	56	66	53
Selling and Marketing
Share-Based Compensation Expense
Share-based compensation	280	349	371
General and Administrative
Share-Based Compensation Expense
Share-based compensation	1,483	2,558	2,173
Research and development
Share-Based Compensation Expense
Share-based compensation	$ 207	$ 312	$ 345