Significant Components of Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred tax assets:
Employee benefits	$ 1,032	$ 1,501
Inventories	7,161	5,797
Goodwill	1,842	2,323
Other	3,761	4,747
Total deferred tax assets	13,796	14,368
Deferred tax liabilities:
Depreciation	45,056	35,402
Foreign earnings	2,665	644
Total deferred tax liabilities	47,721	36,046
Net deferred tax liabilities	$ 33,925	$ 21,678