Deferred Income Tax Assets and Liabilities with Temporary Differences and Carryforwards (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred tax assets:
Benefit plans	$ 1,099	$ 1,021
Inventories	536	506
Other	38	206
Total deferred tax assets	1,673	1,733
Deferred tax liabilities:
Property, plant and equipment	10,299	9,147
Patents and goodwill	2,972	2,719
Other	11	14
Total deferred tax liabilities	13,282	11,880
Net deferred tax liability	11,609	10,147
Balance Sheet classification:
Non-current deferred income tax liability	12,232	10,902
Current deferred income tax asset	623	755
Net deferred tax liability	$ 11,609	$ 10,147