Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current
Accrued liabilities	$ 2,322	$ 3,073
Intangible assets	0	0
Non-qualified stock options	112	31
Other	45	44
Total assets	2,479	3,148
Long- term
Intangible assets	4,517	2,983
Net operating loss carryforward	7,455	4,597
Valuation allowance	(3,321)	(1,552)	$ 0
Non-qualified stock options	1,367	1,354
Foreign tax credits	2,035	1,501
AMT credits	780	995
Other	16	32
Total assets	12,849	9,910
Current
Deferred revenue on maintenance contracts	(429)	(8)
Other	(37)	(32)
Total liabilities	(466)	(40)
Net current deferred tax assets	2,013	3,108
Long- term
Depreciation and amortization	(25,326)	(24,309)
Goodwill	(6,502)	(4,933)
Deferred revenue on maintenance contracts	0	0
Other	(21)	(13)
Total liabilities	(31,849)	(29,255)
Net non-current deferred tax liabilities	$ (19,000)	$ (19,345)