Income Taxes (Details Textuals) (USD $)	12 Months Ended
	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2009	Jul. 31, 2008
Income Taxes (Textuals) [Abstract]
Deferred income tax liability related to other accumulated comprehensive income loss before tax	less than 0.1	less than 0.1
Change in valuation allowance	$ 67,300,000	$ 12,700,000	$ 9,500,000
Valuation allowance	200,000
Federal capital loss carry forwards	200,000
Federal net operating losses relates to stock compensation	189,200,000
Minimum-alternative tax (MAT) tax credits	less than $0.1
Income tax liabilities on foreign undistributed earnings	10,100,000
Unrecognized tax benefits	10,868,000	6,320,000	5,124,000	3,666,000
NOL expiration beginning period for federal tax purpose	2023
NOL expiration period beginning for state tax purpose	2013
Federal [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	230,000,000	97,400,000	84,100,000
Research [Member] | Federal [Member]
Tax Credit Carryforward [Line Items]
Tax credit carryforward, amount	17,400,000	6,400,000	6,000,000
Chinese subsidiary [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	6,400,000
State [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	156,100,000	74,400,000	71,100,000
Research [Member] | State [Member]
Tax Credit Carryforward [Line Items]
Tax credit carryforward, amount	$ 18,200,000	$ 8,000,000	$ 5,700,000