CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) [Abstract]
Revenues	$ 44,258	$ 40,025	$ 86,272	$ 76,028
Cost of revenues	21,135	18,004	40,300	34,784
Gross profit	23,123	22,021	45,972	41,244
Operating expenses:
Research and development	3,581	3,008	6,546	6,462
Sales and marketing	11,505	9,335	23,274	18,487
General and administrative	4,621	4,495	7,943	7,914
Gain from legal settlement	(17,250)	0	(17,250)	0
Total operating expenses	2,457	16,838	20,513	32,863
Income from operations	20,666	5,183	25,459	8,381
Interest and other income (expense), net	255	56	25	350
Income before income tax provision	20,921	5,239	25,484	8,731
Income tax provision	8,012	1,918	9,711	3,196
Net income	$ 12,909	$ 3,321	$ 15,773	$ 5,535
Net income per share:
Basic net income per share (in dollars per share)	$ 0.59	$ 0.15	$ 0.72	$ 0.25
Diluted net income per share (in dollars per share)	$ 0.58	$ 0.15	$ 0.71	$ 0.24
Shares used in the calculation of net income per share:
Weighted average common shares outstanding - basic (in shares)	21,920,000	22,290,000	21,869,000	22,484,000
Weighted average common shares outstanding - diluted (in shares)	22,306,000	22,564,000	22,280,000	22,850,000