Other Financial Statements Details Property, Plant and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Mar. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	$ 2,490,172		$ 2,452,353
Less accumulated depreciation and amortization	1,796,177		1,769,015
Property, plant and equipment, net	693,995		683,338
Depreciation	29,000	$ 30,600
Land
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	73,504		73,447
Buildings and building improvements
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	501,476		499,668
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	1,801,169		1,774,920
Projects in progress
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, gross	$ 114,023		$ 104,318