Significant Accounting Policies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 Facility	Dec. 31, 2012	Dec. 31, 2011
Significant Accounting Policies [Line Items]
Number of production plants	6
Allowance for doubtful accounts	$ 2,083	$ 1,844
Other receivables	2,781	1,732
Disposal or impairment of various assets, gain (loss)	43	(518)	(1,548)
Interest percentage in cost method investee			6.00%
Impairment of goodwill			889
Start-up costs	0	68	184
Research and development expenses	$ 8,416	$ 6,916	$ 7,335
Georgia and Alabama
Significant Accounting Policies [Line Items]
Area of land and leasehold interests	4,220
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