CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Operating activities:
Net income (loss)	$ 11,272	$ (1,072)
Adjustments required to reconcile net income (loss) to net cash provided by (used for) operating activities:
Depreciation and amortization	2,086	3,083
Bad debt expense	42	72
Stock-based compensation	6,899	5,904
Write-down of inventory	891	1,092
Loss on disposal of fixed assets		29
Deferred tax provision	545	555
Gain on settlement of investment		(1,017)
Changes in assets and liabilities:
Accounts receivable	489	(2,124)
Inventories	(4,898)	(4,037)
Prepaid expenses and other assets	359	71
Accounts payable	(286)	(908)
Accrued expenses and other long-term liabilities	1,366	(2,923)
Deferred revenue	76	(84)
Net cash provided by (used for) operating activities	18,841	(1,359)
Investing activities:
Purchases of short-term marketable securities	(24,252)	(17,002)
Proceeds from the sale and maturity of short-term marketable securities	20,500	7,000
Proceeds from settlement of investment		1,017
Expenditures for property and equipment	(2,072)	(1,937)
Net cash used for investing activities	(5,824)	(10,922)
Financing activities:
Proceeds from the exercise of stock options	2,739	11,683
Repurchase of common stock	(10,654)
Issuance of common stock		103
Payments in lieu of issuance of common stock for minimum payroll taxes	(238)
Proceeds from the issuance of stock under employee stock purchase plan	270	197
Net cash (used for) provided by financing activities	(7,883)	11,983
Effect of exchange rate changes on cash	(367)	(441)
Net increase (decrease) in cash and cash equivalents	4,767	(739)
Cash and cash equivalents at beginning of period	5,990	5,831
Cash and cash equivalents at end of period	10,757	5,092
Supplemental disclosures:
Fixed asset additions included in accounts payable	$ 105	$ 82