Stock-Based Compensation - Overview (Details) - shares	9 Months Ended
	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016
Stock options
Stock-Based Awards Outstanding By Award Type
Number of stock-based option awards outstanding at period end (in shares)	1,900,975	1,910,576	2,138,174	2,256,679
2000 Stock Incentive Plan
2000 Stock Incentive Plan
Aggregate maximum number of shares of common stock which may be issued under stock option plan (in shares)	9,462,500
Aggregate net number of stock-based awards granted (in shares)	7,671,924
Aggregate number of stock based awards expired and canceled (in shares)	3,670,231
Aggregate number of stock-based awards exercised (in shares)	5,206,985
Stock-Based Awards Outstanding By Award Type
Number of total stock-based awards outstanding (in shares)	2,464,939
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
Number of stock-based option awards outstanding at period end (in shares)	1,900,975
2000 Stock Incentive Plan | Performance shares
Stock-Based Awards Outstanding By Award Type
Number of stock-based non-option awards outstanding at period end (in shares)	252,089
2000 Stock Incentive Plan | RSUs and restricted stock
Stock-Based Awards Outstanding By Award Type
Number of stock-based non-option awards outstanding at period end (in shares)	304,116
2000 Stock Incentive Plan | Share units
Stock-Based Awards Outstanding By Award Type
Number of stock-based non-option awards outstanding at period end (in shares)	7,759
2001 Employee Stock Purchase Plan | Employee Stock Purchase Plan - ESPP
2000 Stock Incentive Plan
Aggregate maximum number of shares of common stock which may be issued under stock option plan (in shares)	800,000
2001 Employee Stock Purchase Plan
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 (in shares)	684,066