CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Operating activities:
Net income (loss)	$ 2,130	$ (664)
Adjustments required to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	1,196	1,322
Bad debt expense	27	15
Stock-based compensation	8,314	6,719
Write-down of inventory	559	537
Deferred tax provision	450	453
Change in fair value of contingent consideration	219
Changes in assets and liabilities:
Accounts receivable	1,108	1,912
Inventories	(653)	(876)
Prepaid expenses and other assets	(139)	(762)
Accounts payable	(581)	(1,494)
Accrued expenses and other long-term liabilities	(3,732)	(1,978)
Deferred revenue	1,004	(62)
Net cash provided by operating activities	9,902	5,122
Investing activities:
Purchases of marketable securities	(44,920)	(33,849)
Proceeds from the sale and maturity of marketable securities	47,890	25,750
Acquisition of ECP and AIS, net of cash assumed	(15,697)
Purchase of other investment	(750)	(750)
Purchases of property and equipment	(1,496)	(1,236)
Net cash used for investing activities	(14,973)	(10,085)
Financing activities:
Proceeds from the exercise of stock options	2,560	5,318
Payments in lieu of issuance of common stock for minimum payroll taxes	(1,013)	(426)
Proceeds from the issuance of stock under employee stock purchase plan	397	312
Net cash provided by financing activities	1,944	5,204
Effect of exchange rate changes on cash	(306)	428
Net (decrease) increase in cash and cash equivalents	(3,433)	669
Cash and cash equivalents at beginning of period	20,916	9,451
Cash and cash equivalents at end of period	17,483	10,120
Supplemental disclosure of cash flow information:
Cash paid for income taxes	299	870
Supplemental disclosure of non-cash investing and financing activities:
Contingent consideration related to acquisition of ECP	6,000
Fixed asset expenditures incurred, not yet paid	$ 577	$ 92