CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
CONSOLIDATED STATEMENTS OF INCOME [Abstract]
Revenues	$ 218,901	$ 202,593	$ 162,031
Cost of revenues	95,649	93,623	78,081
Gross profit	123,252	108,970	83,950
Operating expenses:
Research and development	18,388	16,327	13,647
Sales and marketing	42,526	42,147	34,742
General and administrative	15,984	16,192	11,333
Total operating expenses	76,898	74,666	59,722
Income from operations	46,354	34,304	24,228
Interest and other income (expense), net	793	(1,262)	994
Income from continuing operations before income tax provision	47,147	33,042	25,222
Income tax provision	16,073	12,239	8,993
Income from continuing operations	31,074	20,803	16,229
Discontinued operations (Note 3)
Loss from discontinued operations, net of tax	(3)	(1,154)	(2,044)
Gain on sale of discontinued operations, net of tax	559	7,682	0
Net income	$ 31,630	$ 27,331	$ 14,185
Basic
Continuing operations (in dollars per share)	$ 1.37	$ 0.92	$ 0.73
Discontinued operations (in dollars per share)	0.03	0.29	(0.09)
Basic net income per share (in dollars per share)	1.40	1.21	0.64
Diluted
Continuing operations (in dollars per share)	1.36	0.91	0.72
Discontinued operations (in dollars per share)	0.02	0.29	(0.09)
Diluted net income per share (in dollars per share)	$ 1.38	$ 1.20	$ 0.63
Shares used in the calculation of net income per share:
Weighted average common shares outstanding - basic (in shares)	22,661,000	22,497,000	22,270,000
Weighted average common shares outstanding - diluted (in shares)	22,883,000	22,787,000	22,575,000
Cash dividends declared per share (in dollars per share)	$ 0.44	$ 0.40	$ 0