CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Income Statement [Abstract]
Sales	$ 249,176	$ 234,684	$ 229,395
Cost of sales	169,862	158,388	153,125
Gross profit	79,314	76,296	76,270
Operating expenses:
General and administrative	22,799	21,301	21,101
Advertising	17,663	21,837	25,182
Discontinued project costs			1,714
Depreciation	1,369	770	660
Total operating expenses	41,831	43,908	48,657
Income from operations	37,483	32,388	27,613
Other income (expense):
Interest income, net	141	190	184
Realized loss on sale of short term investments		(74)
Other, net	300	63	1
Total other income	441	179	185
Income before provision for income taxes	37,924	32,567	27,798
Provision for income taxes	14,105	12,000	10,345
Net income	23,819	20,567	17,453
Net change in unrealized gain (loss) on short term investments		54	(17)
Comprehensive income	$ 23,819	$ 20,621	$ 17,436
Net income per common share:
Basic (in dollars per share)	$ 1.18	$ 1.02	$ 0.87
Diluted (in dollars per share)	$ 1.17	$ 1.02	$ 0.87
Weighted average number of common shares outstanding:
Basic (in shares)	20,232	20,124	20,015
Diluted (in shares)	20,378	20,254	20,136
Cash dividends declared per common share (in dollars per shares)	$ 0.76	$ 0.72	$ 0.68