Significant Accounting Policies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Facility	Dec. 31, 2010	Dec. 31, 2009
Significant Accounting Policies [Line Items]
Number of production plants	6
Allowance for doubtful accounts	$ 1,933	$ 1,711
Other receivables	1,968	1,946
Disposal or impairment of various assets, loss	1,548	1,449	156
Interest percentage in cost-method investee	6.00%
Impairment of goodwill	889	470
Research and development expenses	$ 7,335	$ 5,279	$ 2,902
Georgia and Alabama
Significant Accounting Policies [Line Items]
Area of land and leasehold interests	4,000
Marshfield, Wisconsin
Significant Accounting Policies [Line Items]
Area of land and leasehold interests	490
Maximum
Significant Accounting Policies [Line Items]
Receivables collection period	30 days
Maturity period for all highly liquid investments when purchased to be cash equivalents	3 months
Capitalized software estimated useful life	5 years