Stockholders' Equity and Stock-based Compensation (Details Textual) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended						3 Months Ended
	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2012 Restricted Stock Units (RSUs) [Member]	Oct. 31, 2012 Stock Plan 2006 [Member]	Oct. 31, 2012 Stock Plan 2009 [Member]	Oct. 31, 2012 Stock Plan 2010 [Member]	Oct. 31, 2012 Stock Plan 2011 [Member]	Sep. 14, 2011 Stock Plan 2011 [Member]
Class of Stock [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value			$ 11.0
Total intrinsic value of options exercised	$ 32.9	$ 1.7
Stockholders Equity and Stock Based Compensation (Textual) [Abstract]
Shares reserved for issuance under stock compensation plan				14,102,510	31,000	4,436,579	8,245,548	7,500,000
Maximum increase in percentage of outstanding number of shares of the Company's common stock							5.00%
Period for award grant							10 years
Stockholders Equity and Stock Based Compensation (Additional Textual) [Abstract]
Common stock, shares authorized	500,000,000
Common stock, par value	$ 0.0001