Condensed Consolidated Statements of Operations and Retained Earnings - USD ($)	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Revenues [Abstract]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 224,992,000	$ 203,726,000
Cost of Goods and Services Sold	145,345,000	134,737,000
Gross Profit	79,647,000	68,989,000
Operating Expenses [Abstract]
Selling expenses	25,567,000	23,800,000
General and administrative expenses	21,826,000	18,953,000
Research and Development Expense	3,748,000	2,922,000
Gain (Loss) on Disposition of Property Plant Equipment	11,100,000	0
Amortization of intangibles	3,903,000	3,719,000
Operating Expenses	66,144,000	49,394,000
Income from operations	13,503,000	19,595,000
Other Income & Expenses [Abstract]
Interest and debt expense	4,607,000	5,141,000
Investment (income) loss	(268,000)	(62,000)
Foreign currency exchange (gain) loss	(276,000)	324,000
Other (income) expense, net	(40,000)	(559,000)
Income Tax Expense Benefit [Abstract]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	9,480,000	14,751,000
Income tax expense	1,774,000	3,095,000
Net income	7,706,000	11,656,000
Retained Earnings Accumulated Deficit [Abstract]
Retained earnings - beginning of period	197,897,000	179,735,000
Retained earnings - end of period	$ 206,491,000	$ 191,391,000
Weighted Average Number Of Shares Outstanding Basic [Abstract]
Average basic shares outstanding	23,115,000	22,580,000
Weighted Average Number Of Shares Outstanding [Abstract]
Average diluted shares outstanding	23,610,000	23,028,000
Earnings Per Share Basic [Abstract]
Basic income per share:	$ 0.33	$ 0.52
Earnings Per Share Diluted [Abstract]
Diluted income per share:	0.33	$ 0.51
Common Stock, Dividends, Per Share, Declared	$ 0.05
Accounting Standards Update 2016-01 [Member]
Earnings Per Share Diluted [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 888,000	$ 0