Income Taxes - Components of Net Deferred Tax Assets Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Inventories	$ 835	$ 932
Property and equipment	(4,706)	(4,348)
Accrued liabilities and other deductible differences	46	63
Accrued employee benefits	1,577	1,513
Tax loss and credit carryforwards	4	28
Goodwill	(2,625)	(2,559)
Other taxable differences	(7)	(12)
Valuation allowance		(24)
Total	(4,876)	(4,407)
Net current deferred tax assets	2,444	2,493
Net noncurrent deferred tax liabilities	$ (7,320)	$ (6,900)