Consolidated Statements of Cash Flows (USD $) In Thousands	12 Months Ended
	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2009
Cash flows from operating activities
Net income (loss)	$ 70,688	$ (33,998)	$ (23,413)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	15,042	10,091	9,686
Provision for doubtful accounts	17	265	138
Write-downs for excess and obsolete inventory	2,647	2,949	3,397
Stock-based compensation expense	63,750	36,081	24,579
Accretion of purchase discounts on short-term investments	1,290	837	(271)
Gain on disposal of fixed assets	(3)	(3)	(15)
Change in carrying value of contingent rights liability	(3,598)
Deferred income taxes	(72,638)
Excess tax benefit associated with stock-based compensation	194	(107)	(88)
Changes in operating assets and liabilities:
Accounts receivable	(24,821)	(8,069)	(924)
Inventory	(16,900)	(10,653)	(766)
Prepaids and other	(1,658)	(2,757)	847
Deferred costs	(1,548)	(290)	(606)
Other assets	(240)	50	(50)
Accounts payable	(167)	5,937	(4,926)
Deferred revenue	12,713	11,220	8,698
Other current and noncurrent liabilities	13,331	14,360	4,184
Income taxes payable	(109)	(79)	122
Net cash provided by operating activities	57,990	25,834	20,592
Cash flows from investing activities
Purchases of short-term investments	(144,512)	(122,750)	(101,088)
Proceeds from sales of short-term investments	28,927	10,566	40,443
Proceeds from maturities of short-term investments	84,870	68,860	43,296
Purchases of property and equipment	(9,909)	(5,299)	(4,405)
Proceeds from sale of property and equipment	11	42
Cash paid in purchase acquisitions, net of cash acquired	(4,303)
Net cash used in investing activities	(44,916)	(48,581)	(21,754)
Cash flows from financing activities
Proceeds from issuance of common stock	36,640	12,631	5,761
Repurchases of unvested common stock		(36)
Repurchases of common stock under stock repurchase program			(991)
Excess tax benefit associated with stock-based compensation	(194)	107	88
Net cash provided by financing activities	36,446	12,702	4,858
Effect of exchange rate changes on cash and cash equivalents	(1)	1
Net increase (decrease) in cash and cash equivalents	49,519	(10,044)	3,696
Cash and cash equivalents, beginning of period	31,254	41,298	37,602
Cash and cash equivalents, end of period	80,773	31,254	41,298
Supplemental disclosure of cash flow information
Income taxes paid	1,152	899	673
Supplemental disclosure of non-cash investing and financing activities
Common stock issued for purchase acquisition	28,691
Contingent rights issued for purchase acquisition	$ 9,486