CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Sales	$ 60,791	$ 56,725	$ 133,278	$ 128,359
Cost of sales	42,727	37,812	92,762	86,480
Gross profit	18,064	18,913	40,516	41,879
Operating expenses:
General and administrative	5,747	5,388	11,845	11,187
Advertising	4,382	6,249	10,142	14,134
Depreciation	204	186	398	377
Total operating expenses	10,333	11,823	22,385	25,698
Income from operations	7,731	7,090	18,131	16,181
Other income:
Interest income, net	32	55	60	105
Other, net	23	(4)	76	(8)
Total other income	55	51	136	97
Income before provision for income taxes	7,786	7,141	18,267	16,278
Provision for income taxes	2,887	2,639	6,774	6,019
Net income	4,899	4,502	11,493	10,259
Net change in unrealized gain (loss) on short term investments		16		(19)
Comprehensive income	$ 4,899	$ 4,518	$ 11,493	$ 10,240
Net income per common share:
Basic (in dollars per share)	$ 0.24	$ 0.22	$ 0.57	$ 0.51
Diluted (in dollars per share)	$ 0.24	$ 0.22	$ 0.56	$ 0.51
Weighted average number of common shares outstanding:
Basic (in shares)	20,234	20,126	20,208	20,100
Diluted (in shares)	20,377	20,246	20,355	20,222
Cash dividends declared per common share ((in dollars per share))	$ 0.19	$ 0.18	$ 0.38	$ 0.36