Inventories (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Inventories [Abstract]
Raw materials and supplies	$ 43,349,000	$ 42,281,000
Work-in-process	31,915,000	38,420,000
Finished goods	166,452,000	143,648,000
Valuation reserves	(5,406,000)	(5,156,000)
Inventories	236,310,000	219,193,000
Possible effect of liquidation of LIFO layers on cost of goods sold	19,500,000
Deferred LIFO Gain		8,000,000
Effect of liquidation of LIFO layers on net income	$ 8,000,000
Effect of liquidation of LIFO layers per diluted share after tax	$ 0.13