Other Accrued Liabilities (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Other Accrued Liabilities [Abstract]
Accrued warranty, current	$ 194	$ 156	$ 149
Accrued compensation, including commissions and vacation	945	1,275
Accrued state sales, use and other taxes	2,908	2,719
Accrued professional fees and other accrued liabilities	701	350
Total other accrued liabilities	4,748	$ 4,500
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Estimated tax positions subject to audit	$ 801