Condensed Consolidated Statements of Operations and Retained Earnings - USD ($) shares in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues [Abstract]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 157,790,000	$ 207,609,000	$ 296,860,000	$ 420,321,000
Cost of Goods and Services Sold	101,765,000	134,116,000	196,038,000	271,216,000
Gross Profit	56,025,000	73,493,000	100,822,000	149,105,000
Operating Expenses [Abstract]
Selling expenses	18,563,000	22,877,000	37,258,000	45,632,000
General and administrative expenses	15,554,000	19,153,000	33,983,000	38,753,000
Research and Development Expense	2,896,000	2,999,000	5,665,000	5,791,000
Impairment of Long-Lived Assets to be Disposed of	0	7,000	0	176,000
Amortization of intangibles	3,192,000	3,226,000	6,307,000	6,479,000
Operating Expenses	40,205,000	48,262,000	83,213,000	96,831,000
Income from operations	15,820,000	25,231,000	17,609,000	52,274,000
Other Income & Expenses [Abstract]
Interest and debt expense	3,018,000	3,759,000	6,206,000	7,611,000
Investment (income) loss	(357,000)	(229,000)	(934,000)	(531,000)
Foreign currency exchange (gain) loss	397,000	(296,000)	481,000	(706,000)
Other (income) expense, net	16,911,000	257,000	19,937,000	419,000
Income Tax Expense Benefit [Abstract]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(4,149,000)	21,740,000	(8,081,000)	45,481,000
Income tax expense (benefit)	(45,000)	5,141,000	(1,008,000)	10,303,000
Net income (loss)	(4,104,000)	16,599,000	(7,073,000)	35,178,000
Retained Earnings Accumulated Deficit [Abstract]
Retained earnings - beginning of period	287,472,000	255,038,000	290,441,000	236,459,000
Retained earnings - end of period	$ 281,935,000	$ 270,218,000	$ 281,935,000	$ 270,218,000
Weighted Average Number Of Shares Outstanding Basic [Abstract]
Average basic shares outstanding	23,883	23,631	23,843	23,532
Weighted Average Number Of Shares Outstanding [Abstract]
Average diluted shares outstanding	23,883	23,926	23,843	23,832
Earnings Per Share Basic [Abstract]
Basic income (loss) per share:	$ (0.17)	$ 0.70	$ (0.30)	$ 1.49
Earnings Per Share Diluted [Abstract]
Diluted income (loss) per share:	(0.17)	0.69	(0.30)	1.48
Common Stock, Dividends, Per Share, Declared	$ 0.06	$ 0.06	$ 0.06	$ 0.06