Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Operating activities:
Net (loss) income	$ (1,723)	$ 3,119
Adjustments required to reconcile net (loss) income to net cash (used for) provided by operating activities:
Depreciation and amortization	652	842
Bad debt expense	15	8
Stock-based compensation	3,921	2,679
Write-down of inventory	207	252
Deferred tax provision	226	90
Changes in assets and liabilities:
Accounts receivable	1,971	2,032
Inventories	(1,689)	(1,982)
Prepaid expenses and other assets	292	(65)
Accounts payable	(1,302)	(300)
Accrued expenses and other long-term liabilities	(2,397)	(2,024)
Deferred revenue	(206)	(333)
Net cash (used for) provided by operating activities	(33)	4,318
Investing activities:
Purchases of marketable securities	(15,401)	(11,500)
Proceeds from the sale and maturity of marketable securities	17,750	5,500
Purchase of other investment	(750)
Purchases of property and equipment	(711)	(470)
Net cash provided by (used for) investing activities	888	(6,470)
Financing activities:
Proceeds from the exercise of stock options	1,931	1,228
Payments in lieu of issuance of common stock for minimum payroll taxes	(426)	(238)
Net cash provided by financing activities	1,505	990
Effect of exchange rate changes on cash	(84)	(839)
Net increase (decrease) in cash and cash equivalents	2,276	(2,001)
Cash and cash equivalents at beginning of period	9,451	5,990
Cash and cash equivalents at end of period	11,727	3,989
Supplemental disclosures:
Fixed asset expenditures incurred, not yet paid	$ 86	$ 92