Property, Plant and Equipment (Details) (USD $)	3 Months Ended		9 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2013
Property, Plant and Equipment [Line Items]
Property, plant, and equipment costs	$ 1,967,507,000		$ 1,967,507,000		$ 1,897,685,000
Accumulated depreciation	1,446,942,000		1,446,942,000		1,383,141,000
Property, plant and equipment, net	520,565,000		520,565,000		514,544,000
Depreciation expense	22,200,000	23,000,000	66,700,000	66,000,000
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment costs	55,601,000		55,601,000		47,102,000
Buildings and building improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment costs	407,520,000		407,520,000		396,611,000
Machinery and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment costs	1,442,169,000		1,442,169,000		1,377,814,000
Projects in progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment costs	$ 62,217,000		$ 62,217,000		$ 76,158,000