Income Taxes - Deferred Tax Assets and Liabilities (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Net Operating Loss Carryforwards Used In The Current Period	$ 3,800,000	$ 8,600,000
Deferred income tax assets:
Allowance for uncollectible accounts receivable	342,000	348,000
Accrued compensation expense	5,001,000	3,954,000
Inventory differences	2,317,000	1,949,000
Net operating loss carry-forwards	18,060,000	19,622,000
Deferred revenue	280,000	237,000
Stock-based compensation expense	2,704,000	2,465,000
Uncertain tax positions	559,000	709,000
Federal research and development credit carry-forward	569,000	0
Other	3,197,000	3,762,000
Total deferred income tax assets	33,029,000	33,046,000
Deferred income tax liabilities:
Prepaid expenses	(751,000)	(757,000)
Property and equipment	(21,893,000)	(19,001,000)
Intangible assets	(3,837,000)	(4,107,000)
Other	(1,295,000)	(1,116,000)
Total deferred income tax liabilities	(27,776,000)	(24,981,000)
Valuation allowance	(1,363,000)	(1,225,000)
Net deferred income tax assets	3,890,000	6,840,000
Reported as:
Deferred income tax assets - Current	5,638,000	4,976,000
Deferred income tax assets - Long-term	800,000	4,237,000
Deferred income tax liabilities - Long-term	$ (2,548,000)	$ (2,373,000)