CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) [Abstract]
Revenues	$ 58,854	$ 58,552	$ 117,112	$ 116,248
Cost of revenues	26,693	26,294	53,007	51,989
Gross profit	32,161	32,258	64,105	64,259
Operating expenses:
Research and development	6,075	4,906	12,507	10,139
Sales and marketing	12,484	11,254	24,985	23,078
General and administrative	4,167	4,353	8,717	8,555
Total operating expenses	22,726	20,513	46,209	41,772
Income from operations	9,435	11,745	17,896	22,487
Interest and other income (expense), net	773	6,279	2,084	6,249
Income from continuing operations before income tax provision	10,208	18,024	19,980	28,736
Income tax provision	3,607	6,537	7,049	10,359
Income from continuing operations	6,601	11,487	12,931	18,377
Discontinued operations (Note 4)
Loss from discontinued operations, net of tax	0	(55)	0	(55)
Net income	$ 6,601	$ 11,432	$ 12,931	$ 18,322
Basic
Continuing operations (in dollars per share)	$ 0.29	$ 0.51	$ 0.57	$ 0.82
Discontinued operations (in dollars per share)	0	0	0	(0.01)
Basic net income per share (in dollars per share)	0.29	0.51	0.57	0.81
Diluted
Continuing operations (in dollars per share)	0.29	0.51	0.56	0.81
Discontinued operations (in dollars per share)	0	(0.01)	0	0
Diluted net income per share (in dollars per share)	$ 0.29	$ 0.50	$ 0.56	$ 0.81
Shares used in the calculation of net income per share:
Weighted average common shares outstanding - basic (in shares)	22,679,000	22,522,000	22,648,000	22,494,000
Weighted average common shares outstanding - diluted (in shares)	22,997,000	22,745,000	22,991,000	22,720,000
Cash dividends declared per share (in dollars per share)	$ 0.14	$ 0.12	$ 0.28	$ 0.24