Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred income tax assets:
Allowance for uncollectible accounts receivable	$ 531	$ 366
Accrued compensation expense	5,534	5,492
Inventory differences	2,043	2,401
Net operating loss carryforwards	11,434	13,542
Deferred revenue	118	87
Stock-based compensation expense	2,532	2,479
Uncertain tax positions	0	284
Federal research and development credit carryforward	2,355	1,413
Foreign Tax Credits	600	1,374
Other	5,754	4,173
Total deferred income tax assets	30,901	31,611
Deferred income tax liabilities:
Prepaid expenses	(841)	(708)
Property and equipment	(24,467)	(23,298)
Intangible assets	(6,495)	(4,853)
Other	(1,077)	(1,150)
Total deferred income tax liabilities	(32,880)	(30,009)
Valuation allowance	(1,981)	(1,603)
Total deferred income tax liabilities	(3,960)	(1)
Reported as:
Deferred income tax assets - Current	7,025	6,375
Deferred income tax assets - Long-term	0	9
Deferred income tax liabilities - Current	0	0
Deferred income tax liabilities - Long-term	(10,985)	(6,385)
Total deferred income tax liabilities	$ (3,960)	$ (1)