Property, Plant & Equipment (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 614,263,000	$ 456,248,000
Less accumulated depreciation	(267,833,000)	(252,531,000)
Total property, plant and equipment, net	346,430,000	203,717,000	159,770,000
Depreciation expense related to property, plant and equipment	21,600,000	19,400,000	17,100,000
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	28,021,000	19,775,000
Land improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	17,376,000	10,449,000
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	212,428,000	106,199,000
Machinery and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	310,352,000	289,579,000
Furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	9,144,000	6,839,000
Computer equipment and software [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 36,942,000	$ 23,407,000