Stock-Based Compensation Performance Shares, RSUs, Restricted Stock and Share Unit Awards (Details)		12 Months Ended
	Jul. 31, 2017 USD ($) $ / shares shares	Jul. 31, 2018 USD ($) $ / shares shares	Jul. 31, 2017 USD ($) $ / shares shares	Jul. 31, 2016 USD ($) $ / shares shares
Dividend Equivalents [Abstract]
Accrued during the period | $		$ 300,000	$ 273,000	$ 155,000
Carrying value at period end | $	$ 351,913,000	339,473,000	351,913,000
Income tax benefit from settlement of stock-based awards | $		$ 1,193,000
Net reduction to additional paid in capital from income tax shortfalls | $			$ 670,000	$ 283,000
Performance Shares, RSUs, Restricted Stock and Share Units
Awards (In Shares)
Outstanding, Beginning Balance (in shares) | shares		830,197	217,213	224,165
Granted (in shares) | shares		473,005	705,241	71,605
Settled (in shares) | shares		(354,822)	(61,462)	(16,439)
Forfeited (in shares) | shares		(129,942)	(30,795)	(62,118)
Outstanding, Ending Balance (in shares) | shares	830,197	818,438	830,197	217,213
Vested, Ending Balance (in shares) | shares		207,998
Vested and Expected to Vest, Ending Balance (in shares) | shares		785,543
Weighted Average Grant Date Fair Value
Outstanding, Beginning Balance (in dollars per share) | $ / shares		$ 16.95	$ 28.32	$ 28.26
Granted (in dollars per share) | $ / shares		22.45	14.31	27.45
Settled (in dollars per share) | $ / shares		17.66	26.63	26.35
Forfeited (in dollars per share) | $ / shares		17.26	17.13	27.62
Outstanding, Ending Balance (in dollars per share) | $ / shares	$ 16.95	19.78	$ 16.95	$ 28.32
Vested, Ending Balance (in dollars per share) | $ / shares		28.88
Vested and Expected to Vest, Ending Balance (in dollars per share) | $ / shares		$ 19.92
Aggregate Intrinsic Value
Outstanding, Ending Balance | $		$ 27,500,000
Vested, Ending Balance | $		6,989,000
Vested and Expected to Vest, Ending Balance | $		26,394,000
Additional Disclosures
Total intrinsic value relating to fully vested stock-based awards converted during the period | $		$ 10,473,000	$ 1,039,000	$ 660,000
Performance Shares | Employees
Additional Disclosures
Common stock, conversion ratio (in shares)		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 | Employees
Additional Disclosures
Vesting period (in years)		5 years
Common stock, conversion ratio (in shares)		1
RSUs and restricted stock | Non-Employee Director
Additional Disclosures
Vesting period (in years)		3 years
Common stock, conversion ratio (in shares)		1
Share units
Awards (In Shares)
Granted (in shares) | shares		160,899
Additional Disclosures
Common stock, conversion ratio (in shares)	1		1
Conversion period of vested share units	1 year
Granted units converted into common stock (in shares) | shares		247,664
Number of shares issued as result of conversion | shares		162,391
Number of units settled to date (in shares) | shares		265,348
Dividend Equivalents
Dividend Equivalents [Abstract]
Accrued during the period | $		$ 300,000	$ 273,000	155,000
Paid during the period | $		141,000	176,000	$ 23,000
Carrying value at period end | $	$ 554,000	$ 713,000	$ 554,000