UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS [Abstract]
Net sales	$ 370,845	$ 371,462	$ 738,002	$ 669,965
Cost of sales	283,274	289,529	572,838	520,368
Gross profit	87,571	81,933	165,164	149,597
Selling, general, and administrative expenses	56,340	51,607	111,004	99,661
Depreciation and amortization	2,129	1,723	4,192	3,498
Interest and financing costs	274	400	633	749
Operating expenses	58,743	53,730	115,829	103,908
Operating income	28,828	28,203	49,335	45,689
Other income and (expense)	(141)	380	130	380
Earnings before tax	28,687	28,583	49,465	46,069
Provision for income taxes	11,466	11,808	18,821	18,623
Net earnings	$ 17,221	$ 16,775	$ 30,644	$ 27,446
Net earnings per common share-basic (in dollars per share)	$ 1.24	$ 1.21	$ 2.21	$ 1.97
Net earnings per common share-diluted (in dollars per share)	$ 1.23	$ 1.21	$ 2.19	$ 1.95
Weighted average common shares outstanding-basic (in shares)	13,879	13,818	13,843	13,941
Weighted average common shares outstanding-diluted (in shares)	14,008	13,884	14,021	14,055