CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) [Abstract]
Revenues	$ 52,772	$ 52,876	$ 169,020	$ 161,941
Cost of revenues	23,368	23,274	75,357	70,985
Gross profit	29,404	29,602	93,663	90,956
Operating expenses:
Research and development	4,776	4,428	14,915	13,840
Sales and marketing	10,629	10,395	33,707	31,766
General and administrative	3,159	3,524	11,714	11,301
Total operating expenses	18,564	18,347	60,336	56,907
Income from operations	10,840	11,255	33,327	34,049
Interest and other income (expense), net	(52)	231	6,197	716
Income from continuing operations before income tax provision	10,788	11,486	39,524	34,765
Income tax provision	3,929	3,532	14,288	11,993
Income from continuing operations	6,859	7,954	25,236	22,772
Discontinued operations (Note 4)
Income (loss) from discontinued operations, net of tax	(15)	4	(70)	(3)
Net income	$ 6,844	$ 7,958	$ 25,166	$ 22,769
Basic
Continuing operations (in dollars per share)	$ 0.30	$ 0.35	$ 1.12	$ 1.00
Discontinued operations (in dollars per share)	0	0	0	0
Basic net income per share (in dollars per share)	0.30	0.35	1.12	1.00
Diluted
Continuing operations (in dollars per share)	0.30	0.35	1.11	1.00
Discontinued operations (in dollars per share)	0	0	0	0
Diluted net income per share (in dollars per share)	$ 0.30	$ 0.35	$ 1.11	$ 1.00
Shares used in the calculation of net income per share:
Weighted average common shares outstanding - basic (in shares)	22,535,000	22,725,000	22,508,000	22,684,000
Weighted average common shares outstanding - diluted (in shares)	22,789,000	22,889,000	22,753,000	22,884,000
Cash dividends declared per share (in dollars per share)	$ 0.14	$ 0.11	$ 0.38	$ 0.33