Property, Plant, and Equipment (Details) - USD ($)	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Other Depreciation and Amortization	$ 16,184,000	$ 17,775,000	$ 20,584,000
Land and land improvements	4,985,000	5,105,000
Buildings	39,930,000	39,121,000
Machinery, equipment, and leasehold improvements	228,140,000	230,754,000
Construction in progress	12,950,000	12,242,000
Property, plant, and equipment	286,005,000	287,222,000
Less accumulated depreciation	206,532,000	199,919,000
Net property, plant, and equipment	79,473,000	87,303,000
Capitalized Computer Software, Gross	37,864,000	37,832,000
Capital Computer Software Accumulated Amortization	22,962,000	20,225,000
Capitalized Computer Software Depreciation Expense	$ 2,937,000	$ 3,045,000	$ 3,151,000