Schedule II - Valuation and Qualifying Accounts (Details) - USD ($)	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Accounts Receivable - Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 4,284,000	$ 629,000	$ 854,000
Charged to cost and expense	3,000	4,404,000	184,000
Amounts written off	147,000	749,000	409,000
Balance at end of period	4,140,000	4,284,000	629,000
Accounts Receivable - Allowance for Customer-Payment Discrepancies [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	703,000	852,000	577,000
Charged to cost and expense	718,000	(299,000)	91,000
Amounts written off	670,000	(150,000)	(184,000)
Balance at end of period	751,000	703,000	852,000
Inventory - Allowance for Excess and Obsolete Inventory [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	3,626,000	2,675,000	2,708,000
Charged to cost and expense	3,864,000	4,518,000	1,635,000
Amounts written off	3,365,000	3,567,000	1,668,000
Balance at end of period	$ 4,125,000	$ 3,626,000	$ 2,675,000