Stock-Based Compensation - Overview (Details) - shares	3 Months Ended
	Oct. 31, 2015	Dec. 09, 2015	Jul. 31, 2015
Stock options
Stock-Based Awards Outstanding By Award Type (In Shares)
Number of stock-based awards outstanding at period end	2,398,498		2,119,683
2000 Stock Incentive Plan
2000 Stock Incentive Plan
Aggregate maximum number of shares of common stock which may be issued under stock option plan	8,962,500
Aggregate net number of stock-based awards granted	7,771,923
Aggregate number of stock based awards expired and canceled	3,061,238
Aggregate number of stock-based awards exercised	5,138,962
Stock-Based Awards Outstanding By Award Type (In Shares)
Number of total stock-based awards outstanding	2,632,961
2000 Stock Incentive Plan | Stock options
2000 Stock Incentive Plan
Maximum term for grants of incentive and non-qualified stock-based awards, excluding incentive stock-based awards granted to stockholders who own more than 10% of the voting power	10 years
Percentage of a stockholder's voting power that limits the contractual term of an incentive stock-based award	10.00%
Maximum term for incentive stock-based awards granted to stockholders who own more than 10% of the voting power	5 years
Stock-Based Awards Outstanding By Award Type (In Shares)
Number of stock-based awards outstanding at period end	2,398,498
2000 Stock Incentive Plan | Performance shares
Stock-Based Awards Outstanding By Award Type (In Shares)
Number of stock-based awards outstanding at period end	176,165
2000 Stock Incentive Plan | RSUs and restricted stock
Stock-Based Awards Outstanding By Award Type (In Shares)
Number of stock-based awards outstanding at period end	49,795
2000 Stock Incentive Plan | Share units
Stock-Based Awards Outstanding By Award Type (In Shares)
Number of stock-based awards outstanding at period end	8,503
2001 Employee Stock Purchase Plan | Employee Stock Purchase Plan - ESPP
2001 Employee Stock Purchase Plan
Total number of common shares reserved for issuance under employee stock purchase plan	675,000
Discount rate from market value, on purchase date, offered to employees participating in the Employee Stock Purchase Plan (ESPP)	85.00%
Total number of shares of common stock issued to employees under employee stock purchase plan and through the end of the reporting period	599,057
Subsequent Event [Member] | Employee Stock Purchase Plan - ESPP
2001 Employee Stock Purchase Plan
Increase in total common shares reserved for an issuance under the Company's ESPP requested by the Company		800,000