Income Taxes (Details 2) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Allowance for doubtful accounts	$ 559	$ 357
Accrued liabilities and other	2,173	3,156
Stock-based compensation expense	599	910
Net federal, state and foreign operating loss carryforwards	1,432	1,292
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	0	1,207
Deferred tax assets	4,763	6,922
Valuation allowance on deferred tax assets	(1,502)	(1,320)
Deferred tax liabilities:
Intangible assets, property and equipment, principally due to difference in depreciation and amortization	5,312	7,668
Net deferred tax liabilities	$ (2,051)	$ (2,066)