CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
CONSOLIDATED STATEMENTS OF INCOME [Abstract]
Revenues	$ 202,593	$ 162,031	$ 180,878
Cost of revenues	93,623	78,081	79,903
Gross profit	108,970	83,950	100,975
Operating expenses:
Research and development	16,327	13,647	13,577
Sales and marketing	42,147	34,742	43,800
General and administrative	16,192	11,333	12,825
Gain from legal settlement	0	0	(17,250)
Total operating expenses	74,666	59,722	52,952
Income from operations	34,304	24,228	48,023
Interest and other income (expense), net	(1,262)	994	253
Income from continuing operations before income tax provision	33,042	25,222	48,276
Income tax provision	12,239	8,993	17,149
Income from continuing operations	20,803	16,229	31,127
Discontinued operations (Note 3)
Loss from discontinued operations, net of tax	(1,154)	(2,044)	(3,668)
Gain on sale of discontinued operations, net of tax	7,682	0	0
Net income	$ 27,331	$ 14,185	$ 27,459
Basic net income (loss) per share:
Continuing operations (in dollars per share)	$ 0.92	$ 0.73	$ 1.42
Discontinued operations (in dollars per share)	$ 0.29	$ (0.09)	$ (0.17)
Basic net income per share (in dollars per share)	$ 1.21	$ 0.64	$ 1.25
Diluted net income (loss) per share:
Continuing operations (in dollars per share)	$ 0.91	$ 0.72	$ 1.39
Discontinued operations (in dollars per share)	$ 0.29	$ (0.09)	$ (0.16)
Diluted net income per share (in dollars per share)	$ 1.20	$ 0.63	$ 1.23
Shares used in the calculation of net income per share:
Weighted average common shares outstanding - basic (in shares)	22,497,000	22,270,000	21,946,000
Weighted average common shares outstanding - diluted (in shares)	22,787,000	22,575,000	22,381,000
Cash dividends declared per share (in dollars per share)	$ 0.40	$ 0	$ 1.00