CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Operating activities:
Net income	$ 3,729	$ 11,272
Adjustments required to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,863	2,086
Bad debt expense	11	42
Stock-based compensation	8,367	6,899
Write-down of inventory	641	891
Deferred tax provision	679	545
Changes in assets and liabilities:
Accounts receivable	123	489
Inventories	(69)	(4,898)
Prepaid expenses and other assets	(345)	359
Accounts payable	(1,679)	(286)
Accrued expenses and other long-term liabilities	104	1,366
Deferred revenue	147	76
Net cash provided by operating activities	13,571	18,841
Investing activities:
Purchases of marketable securities	(58,330)	(24,252)
Proceeds from the sale and maturity of marketable securities	52,264	20,500
Purchase of other investment	(750)
Purchases of property and equipment	(2,301)	(2,072)
Net cash used for investing activities	(9,117)	(5,824)
Financing activities:
Proceeds from the exercise of stock options	8,227	2,739
Repurchase of common stock		(10,654)
Payments in lieu of issuance of common stock for minimum payroll taxes	(426)	(238)
Proceeds from the issuance of stock under employee stock purchase plan	312	270
Net cash provided by (used for) financing activities	8,113	(7,883)
Effect of exchange rate changes on cash	614	(367)
Net increase in cash and cash equivalents	13,181	4,767
Cash and cash equivalents at beginning of period	9,451	5,990
Cash and cash equivalents at end of period	22,632	10,757
Supplemental disclosures:
Cash paid for income taxes	1,106	75
Fixed asset expenditures incurred, not yet paid	$ 92	$ 105