Stock-Based Compensation - Performance Shares, RSUs, Restricted Stock and Share Unit Awards (Details)	3 Months Ended
	Oct. 31, 2017 USD ($) $ / shares shares	Oct. 31, 2016 USD ($)	Jul. 31, 2017 USD ($)
Additional Disclosures
Accrual of dividend equivalents, net of reversal | $	$ 61,000	$ 129,000
Carrying value at period end | $	$ 350,213,000		$ 351,913,000
Performance Shares, RSUs, Restricted Stock and Share Units
Awards (in Shares)
Outstanding, Beginning Balance (in shares)	830,197
Granted (in shares)	307,194
Settled (in shares)	(100,321)
Forfeited (in shares)	(61,520)
Outstanding, Ending Balance (in shares)	975,550
Vested, Ending Balance (in shares)	309,853
Vested and Expected to Vest, Ending Balance (in shares)	941,258
Weighted Average Grant Date Fair Value
Outstanding, Beginning Balance (in dollars per share) | $ / shares	$ 16.95
Granted (in dollars per share) | $ / shares	18.25
Settled (in dollars per share) | $ / shares	20.67
Forfeited (in dollars per share) | $ / shares	18.88
Outstanding, Ending Balance (in dollars per share) | $ / shares	16.86
Vested, Ending Balance (in dollars per share) | $ / shares	17.55
Vested and Expected to Vest, Ending Balance (in dollars per share) | $ / shares	$ 16.87
Aggregate Intrinsic Value
Outstanding, Ending Balance | $	$ 20,984,000
Vested, Ending Balance | $	6,665,000
Vested and Expected to Vest, Ending Balance | $	20,246,000
Additional Disclosures
Total intrinsic value of stock-based awards settled | $	$ 1,937,000	$ 425,000
Performance Shares | Employees
Additional Disclosures
Common Stock conversion ratio	1
Performance Shares | Employees | Granted prior to fiscal 2014
Additional Disclosures
Vesting period (in years)	5 years 3 months 19 days
Performance Shares | Employees | Granted since fiscal 2014
Additional Disclosures
Performance period (in years)	3 years
RSUs and restricted stock | Non-Employee Director
Additional Disclosures
Vesting period (in years)	3 years
Common Stock conversion ratio	1
RSUs and restricted stock | Employees
Additional Disclosures
Vesting period (in years)	5 years
Common Stock conversion ratio	1
Share units
Additional Disclosures
Common Stock conversion ratio	1
Cumulative number of units settled as of the date (in shares)	14,777
Share units | Granted on or after July 31, 2017
Additional Disclosures
Conversion period of fully-vested share units into Common Stock from grant date (in years)	1 year
Dividend Equivalents
Additional Disclosures
Accrual of dividend equivalents, net of reversal | $	$ 61,000
Dividend equivalents paid | $	115,000
Carrying value at period end | $	$ 500,000		$ 554,000
2000 Stock Incentive Plan | Performance Shares
Awards (in Shares)
Outstanding, Ending Balance (in shares)	277,881
2000 Stock Incentive Plan | RSUs and restricted stock
Awards (in Shares)
Outstanding, Ending Balance (in shares)	430,063
2000 Stock Incentive Plan | Share units
Awards (in Shares)
Outstanding, Ending Balance (in shares)	267,606