Supplemental Balance Sheets and Statements of Operations Detail (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Total property and equipment
Property, plant and equipment, gross	$ 1,098,335	$ 1,075,080
Accumulated depreciation	(805,687)	(771,398)
Property, plant and equipment	292,648	303,682
Land and land improvements
Total property and equipment
Useful life	20 years	20 years
Property, plant and equipment, gross	25,965	25,824
Buildings
Total property and equipment
Property, plant and equipment, gross	163,062	145,977
Buildings | Minimum
Total property and equipment
Useful life	20 years	20 years
Buildings | Maximum
Total property and equipment
Useful life	40 years	40 years
Machinery and equipment
Total property and equipment
Useful life	10 years	10 years
Property, plant and equipment, gross	824,878	809,885
Furniture and fixtures
Total property and equipment
Property, plant and equipment, gross	69,676	62,071
Furniture and fixtures | Minimum
Total property and equipment
Useful life	4 years	4 years
Furniture and fixtures | Maximum
Total property and equipment
Useful life	10 years	10 years
Construction in progress
Total property and equipment
Property, plant and equipment, gross	$ 14,754	$ 31,323