Stock-Based Compensation - Performance Shares, RSUs, Restricted Stock and Share Unit Awards (Details)		3 Months Ended				9 Months Ended
	Apr. 30, 2017 USD ($) $ / shares shares	Apr. 30, 2017 USD ($) $ / shares shares	Jan. 31, 2017 $ / shares shares	Oct. 31, 2016 $ / shares shares	Apr. 30, 2016 USD ($)	Apr. 30, 2017 USD ($) $ / shares shares	Apr. 30, 2016 USD ($)	Jul. 31, 2016 USD ($)
Additional Disclosures
Accrual of dividend equivalents, net of reversal | $						$ 228,000	$ 97,000
Carrying value at period end | $	$ 394,103,000	$ 394,103,000				394,103,000		$ 450,795,000
Cash payments to remit employee's minimum statutory tax withholding requirements related to the net settlement of stock-based awards | $						$ 244,000	74,000
Performance Shares, RSUs, Restricted Stock and Share Units
Awards (in Shares)
Outstanding, Beginning Balance (in shares)		567,976	592,036	217,213		217,213
Granted (in shares)		5,836	2,632	418,684
Converted to common stock (in shares)			(19,866)	(38,706)
Forfeited (in shares)		(9,848)	(6,826)	(5,155)
Outstanding, Ending Balance (in shares)	563,964	563,964	567,976	592,036		563,964
Vested, Ending Balance (in shares)	35,400	35,400				35,400
Vested and Expected to Vest, Ending Balance (in shares)	540,161	540,161				540,161
Weighted Average Grant Date Fair Value
Outstanding, Beginning Balance (in dollars per share) | $ / shares		$ 17.34	$ 17.80	$ 28.32		$ 28.32
Granted (in dollars per share) | $ / shares		11.04	11.40	13.10
Converted to common stock (in dollars per share) | $ / shares			29.41	14.75
Forfeited (in dollars per share) | $ / shares		13.64	19.65	25.10
Outstanding, Ending Balance (in dollars per share) | $ / shares	$ 17.34	17.34	$ 17.34	$ 17.80		17.34
Vested, Ending Balance (in dollars per share) | $ / shares	26.94	26.94				26.94
Vested and Expected to Vest, Ending Balance (in dollars per share) | $ / shares	$ 17.34	$ 17.34				$ 17.34
Aggregate Intrinsic Value
Outstanding, Ending Balance | $	$ 7,901,000	$ 7,901,000				$ 7,901,000
Vested, Ending Balance | $						496,000
Vested and Expected to Vest, Ending Balance | $	$ 7,568,000	7,568,000				7,568,000
Additional Disclosures
Total intrinsic value of stock-based awards settled | $		$ 0			$ 0	$ 633,000	$ 275,000
Performance Shares
Additional Disclosures
RSUs and restricted stock into common stock, conversion ratio	1	1				1
Performance Shares | Granted prior to fiscal 2014
Additional Disclosures
Vesting period (in years)						5 years 3 months 19 days
Performance Shares | Granted since fiscal 2014
Additional Disclosures
Performance period (in years)						3 years	3 years
RSUs and restricted stock | Non-Employee Director
Additional Disclosures
Vesting period (in years)						3 years
RSUs and restricted stock into common stock, conversion ratio	1	1				1
RSUs and restricted stock | Employees
Additional Disclosures
Vesting period (in years)						5 years
RSUs and restricted stock into common stock, conversion ratio	1	1				1
Share units
Additional Disclosures
RSUs and restricted stock into common stock, conversion ratio	1	1				1
Share-Based Compensation Arrangement By Share-Based Payment Award, Equity Instruments Other Than Options, Granted Units Converted Into Common Stock	744
Dividend Equivalents
Additional Disclosures
Accrual of dividend equivalents, net of reversal | $						$ 228,000
Dividend equivalents paid | $						164,000
Carrying value at period end | $	$ 521,000	$ 521,000				$ 521,000		$ 457,000
2000 Stock Incentive Plan | Performance Shares
Awards (in Shares)
Outstanding, Ending Balance (in shares)	252,089	252,089				252,089
2000 Stock Incentive Plan | RSUs and restricted stock
Awards (in Shares)
Outstanding, Ending Balance (in shares)	304,116	304,116				304,116
2000 Stock Incentive Plan | Share units
Awards (in Shares)
Outstanding, Ending Balance (in shares)	7,759	7,759				7,759