Condensed Consolidated Statements of Cash Flows (USD $) In Thousands	6 Months Ended
	Sep. 30, 2009	Sep. 30, 2010 Restated [Member]
Cash flows from operating activities:
Net income	$ 6,132	$ 17,008
Adjustments to reconcile net income to net cash (used in) provided by operations:
Depreciation and amortization	4,704	5,428
Stock-based compensation expense	6,918	7,825
Stock-based compensation expense-non-employee	30	181
Provision for excess and obsolete inventory		580
Allowance for doubtful accounts	52	(4)
Write-off of prepaid value added taxes		431
Deferred income taxes	(1,111)	(793)
Other non-cash items	382	1,107
Changes in operating asset and liability accounts:
Accounts receivable	3,010	(32,504)
Inventory	6,235	(10,348)
Prepaid expenses and other current assets	712	(6,620)
Accounts payable and accrued expenses	(4,810)	8,011
Deferred revenue	(567)	7,820
Net cash (used in) provided by operating activities	21,687	(1,878)
Cash flows from investing activities:
Purchase of property, plant and equipment	(2,741)	(17,950)
Purchase of marketable securities	(40,533)	(25,283)
Proceeds from the maturity of marketable securities	33,374	15,482
Change in restricted cash	(546)	253
Purchase of intangible assets	(843)	(1,615)
Purchase of minority investment		(8,000)
Change in other assets	(617)	(182)
Net cash used in investing activities	(11,906)	(37,295)
Cash flows from financing activities:
Proceeds from exercise of employee stock options and ESPP	4,068	1,574
Net cash provided by financing activities	4,068	1,574
Effect of exchange rate changes on cash and cash equivalents	2,229	2,620
Net (decrease) increase in cash and cash equivalents	16,078	(34,979)
Cash and cash equivalents at beginning of period	70,674	87,594
Cash and cash equivalents at end of period	86,752	52,615
Supplemental schedule of cash flow information:
Non-cash contingent consideration in connection with acquisitions	10,828	10,003
Cash paid for income taxes	2,531	6,925
Non-cash issuance of common stock	$ 320	$ 419