Secured Credit Facility (Details)		12 Months Ended
	Jun. 06, 2017 USD ($) $ / shares	Jul. 31, 2018 USD ($)	Jul. 31, 2017 USD ($)	Jul. 31, 2016 USD ($)	Feb. 23, 2016 USD ($)
Line of Credit Facility [Line Items]
Repayment of long-term debt under Term Loan Facility		$ 18,960,000	$ 33,567,000	$ 77,353,000
Current portion of long-term debt		17,211,000	15,494,000
Non-current portion of long-term debt, net		148,087,000	176,228,000
Outstanding standby letters of credit at period end		3,166,000
Outstanding commercial letters of credit at period end		0
Targeted quarterly dividend per share (in usd per share) | $ / shares	$ 0.10
Secured Credit Facility
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity					$ 400,000,000
Long-term Debt		165,298,000	191,722,000
Current portion of long-term debt		17,211,000	15,494,000
Non-current portion of long-term debt, net		148,087,000	176,228,000
Interest expense related to credit facility		$ 9,614,000	$ 11,106,000	$ 6,933,000
Weighted average interest rate		5.40%	4.90%	5.00%
Maximum amount of available cash on hand in leverage ratio calculation prior to the June 2017 amendment	$ 50,000,000
Term Loan Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity					250,000,000
Repayment of long-term debt under Term Loan Facility		$ 18,960,000	$ 33,567,000
Balloon payment paid	$ 22,500,000
Long-term debt, gross		120,121,000	139,080,000
Net deferred financing cost recorded as a direct deduction of non-current portion of debt		3,427,000	4,763,000
Long-term Debt		116,694,000	134,317,000
Revolving Loan Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity					150,000,000
Long-term Debt		$ 48,604,000	$ 57,405,000
Revolving Loan Facility | Letter of Credit
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity					$ 25,000,000
June 2017 Amendment To Credit Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Fixed coverage ratio		2.33
Leverage ratio		2.19
Maximum leverage ratio		3.0
Federal Funds Effective Swap Rate | Revolving Loan Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Basis spread on variable rate		0.50%
Adjusted LIBO Rate | Revolving Loan Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.00%
Minimum | Revolving Loan Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Long-term Debt		$ 34,904,000
Minimum | June 2017 Amendment To Credit Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Fixed coverage ratio		1.25
Maximum | Revolving Loan Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Long-term Debt		$ 66,804,000