Property, Plant and Equipment (Details) (USD $)	12 Months Ended
	Mar. 31, 2011	Mar. 31, 2010	Mar. 31, 2009
Property, Plant and Equipment [Line Items]
Property, plant, and equipment costs	$ 1,829,677,000	$ 1,664,437,000
Accumulated depreciation	1,289,164,000	1,171,398,000
Property, plant and equipment, net	540,513,000	493,039,000
Depreciation expense	92,700,000	86,400,000	93,300,000
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment costs	46,497,000	39,671,000
Buildings and building improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment costs	375,611,000	349,964,000
Machinery and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment costs	1,306,367,000	1,190,548,000
Projects in progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment costs	$ 101,202,000	$ 84,254,000