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Acquisitions - Assets Acquired and Liabilities Assumed (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Feb. 21, 2012
Allocations of the aggregate purchase price
Goodwill	$ 35,584us-gaap_Goodwill	$ 35,584us-gaap_Goodwill
Niotan Incorporated
Allocations of the aggregate purchase price
Cash			153
Accounts receivable			479
Inventories			7,305
Prepaid expenses			186
Property, plant and equipment			15,122
Goodwill			35,584
Intangible assets			22,420
Deferred income taxes			311
Other noncurrent assets			1,303
Current liabilities			(873)
Long-term liabilities			(18)
Total net assets acquired			$ 81,972