Stock-Based Compensation - Performance Shares, RSUs, Restricted Stock and Share Unit Awards (Details)		3 Months Ended
	Oct. 31, 2018 USD ($) $ / shares shares	Oct. 31, 2018 USD ($) $ / shares shares	Oct. 31, 2017 USD ($)	Jul. 31, 2018 USD ($)
Additional Disclosures
Accrual of dividend equivalents, net of reversal | $		$ 82,000	$ 61,000
Carrying value at period end | $	$ 360,844,000	$ 360,844,000		$ 339,473,000
Performance Shares, RSUs, Restricted Stock and Share Units
Awards (in Shares)
Outstanding, Beginning Balance (in shares)		818,438
Granted (in shares)		177,908
Settled (in shares)		(121,790)
Forfeited (in shares)		(17,659)
Outstanding, Ending Balance (in shares)	856,897	856,897
Vested, Ending Balance (in shares)	216,718	216,718
Vested and Expected to Vest, Ending Balance (in shares)	819,625	819,625
Weighted Average Grant Date Fair Value
Outstanding, Beginning Balance (in dollars per share) | $ / shares		$ 19.78
Granted (in dollars per share) | $ / shares		34.27
Settled (in dollars per share) | $ / shares		21.08
Forfeited (in dollars per share) | $ / shares		27.23
Outstanding, Ending Balance (in dollars per share) | $ / shares	$ 22.44	22.44
Vested, Ending Balance (in dollars per share) | $ / shares	27.71	27.71
Vested and Expected to Vest, Ending Balance (in dollars per share) | $ / shares	$ 22.58	$ 22.58
Aggregate Intrinsic Value
Outstanding, Ending Balance | $	$ 23,925,000	$ 23,925,000
Vested, Ending Balance | $	6,051,000
Vested and Expected to Vest, Ending Balance | $	$ 22,884,000	22,884,000
Additional Disclosures
Total intrinsic value of stock-based awards settled | $		$ 4,210,000	$ 1,937,000
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	1
RSUs and restricted stock | Employees
Additional Disclosures
Vesting period (in years)		5 years
Common Stock conversion ratio	1	1
Share units
Additional Disclosures
Common Stock conversion ratio	1	1
Cumulative number of units settled as of the date (in shares)	270,979	270,979
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
Stock Options
Additional Disclosures
Total intrinsic value of stock-based awards settled | $		$ 561,000
Dividend Equivalents
Additional Disclosures
Accrual of dividend equivalents, net of reversal | $		82,000
Dividend equivalents paid | $		259,000
Carrying value at period end | $	$ 536,000	$ 536,000		$ 713,000
2000 Stock Incentive Plan | Performance Shares
Awards (in Shares)
Outstanding, Ending Balance (in shares)	260,262	260,262
2000 Stock Incentive Plan | RSUs and restricted stock
Awards (in Shares)
Outstanding, Ending Balance (in shares)	440,829	440,829
2000 Stock Incentive Plan | Share units
Awards (in Shares)
Outstanding, Ending Balance (in shares)	155,806	155,806