Accrued Liabilities - Accrued Liabilities Schedule (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Accrued compensation and benefits	$ 17,745	$ 16,144
Accrued warranties	2,571	2,628	$ 2,594	$ 2,309
Professional and legal fees	2,154	1,541
Taxes other than income	3,550	3,787
General services administration liability	5,267	0
Other accrued liabilities	5,040	3,262
Total accrued liabilities	$ 36,327	$ 27,362