Stock-Based Compensation - Performance Shares, RSUs, Restricted Stock and Share Unit Awards, and Additional Information (Details)	1 Months Ended	3 Months Ended				9 Months Ended
	May 31, 2020 USD ($) $ / shares shares	Apr. 30, 2020 USD ($) $ / shares shares	Jan. 31, 2020 $ / shares shares	Oct. 31, 2019 $ / shares shares	Apr. 30, 2019 USD ($)	Apr. 30, 2020 USD ($) $ / shares shares	Apr. 30, 2019 USD ($)	Jul. 31, 2019 USD ($)
Additional Disclosures
Accrual of dividend equivalents, net of reversal		$ 56,000			$ 82,000	$ 169,000	$ 248,000
Carrying value at period end		405,907,000				405,907,000		$ 352,629,000
Settlement of stock-based awards, income tax expense (benefit)		$ 122,000			(52,000)	$ (349,000)	(505,000)
Subsequent Event
Additional Disclosures
Estimated fair value, net of estimated forfeitures of options	$ 2,800,000
Performance Shares, RSUs, Restricted Stock and Share Units
Awards (in Shares)
Outstanding, Beginning Balance (in shares) | shares	903,225	931,192	933,555	954,676		954,676
Granted (in shares) | shares		5,064		219,425
Settled (in shares) | shares		(3,884)	(527)	(199,466)
Forfeited (in shares) | shares		(29,147)	(1,836)	(41,080)
Outstanding, Ending Balance (in shares) | shares		903,225	931,192	933,555		903,225
Vested, Ending Balance (in shares) | shares		326,186				326,186
Vested and Expected to Vest, Ending Balance (in shares) | shares		860,595				860,595
Weighted Average Grant Date Fair Value
Outstanding, Beginning Balance (in dollars per share) | $ / shares	$ 24.96	$ 24.92	$ 24.91	$ 22.40		$ 22.40
Granted (in dollars per share) | $ / shares		21.64		27.69
Settled (in dollars per share) | $ / shares		23.26	11.40	16.80
Forfeited (in dollars per share) | $ / shares		23.40	23.95	21.00
Outstanding, Ending Balance (in dollars per share) | $ / shares		24.96	$ 24.92	$ 24.91		24.96
Vested, Ending Balance (in dollars per share) | $ / shares		24.93				24.93
Vested and Expected to Vest, Ending Balance (in dollars per share) | $ / shares		$ 25.12				$ 25.12
Aggregate Intrinsic Value
Outstanding, Ending Balance		$ 16,719,000				$ 16,719,000
Vested, Ending Balance						6,038,000
Vested and Expected to Vest, Ending Balance		15,930,000				15,930,000
Additional Disclosures
Total intrinsic value of stock-based awards settled		$ 70,000			28,000	$ 5,895,000	4,252,000
Performance Shares | Employees | Granted since fiscal 2014
Additional Disclosures
Performance period						3 years
RSUs and restricted stock | Non-Employee Director
Additional Disclosures
Common Stock conversion ratio		1				1
RSUs and restricted stock | Non-Employee Director | Granted prior to July 31, 2019
Additional Disclosures
Vesting period						3 years
RSUs and restricted stock | Non-Employee Director | Granted after July 31, 2019
Additional Disclosures
Vesting period						5 years
RSUs and restricted stock | Employees
Additional Disclosures
Vesting period						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) | shares		431,142				431,142
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		$ 56,000				$ 169,000
Dividend equivalents paid		1,000				287,000
Carrying value at period end		659,000				659,000		$ 777,000
Stock options
Additional Disclosures
Total intrinsic value of stock-based awards settled		$ 5,000			$ 0	$ 1,869,000	$ 561,000
Stock options | Subsequent Event
Additional Disclosures
Vesting period	5 years
Authorized for issuance (in shares) | shares	342,300
Contractual life	10 years