Secured Credit Facility (Details)			3 Months Ended		9 Months Ended
	Jun. 06, 2017 USD ($)	Apr. 30, 2017 USD ($) $ / shares	Apr. 30, 2017 USD ($)	Apr. 30, 2016 USD ($)	Apr. 30, 2017 USD ($)	Apr. 30, 2016 USD ($)	Jul. 31, 2016 USD ($)	Feb. 23, 2016 USD ($)
Line of Credit Facility [Line Items]
Current portion of long-term debt		$ 14,387,000	$ 14,387,000		$ 14,387,000		$ 11,067,000
Non-current portion of long-term debt, net		$ 211,509,000	211,509,000		211,509,000		239,969,000
Repayment of term loan facility					7,747,000	$ 3,125,000
Targeted quarterly dividend per share | $ / shares		$ 0.10
Secured Credit Facility
Line of Credit Facility [Line Items]
Long-term Debt		$ 225,896,000	225,896,000		225,896,000		251,036,000
Current portion of long-term debt		14,387,000	14,387,000		14,387,000		11,067,000
Non-current portion of long-term debt, net		211,509,000	211,509,000		211,509,000		239,969,000
Secured credit facility, maximum borrowing capacity								$ 400,000,000
Interest expense including amortization of deferred financing costs			2,641,000	$ 2,981,000	8,524,000	$ 2,981,000
Outstanding standby letters of credit at period end		3,845,000	3,845,000		3,845,000
Outstanding commercial letters of credit at period end		0	0		0
Maximum amount of available cash on hand that can be used in leverage ratio calculation		$ 50,000,000	50,000,000		50,000,000
Leverage ratio		2.56
Fixed coverage ratio		2.53
Term Loan Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Long-term debt, gross		$ 164,900,000	164,900,000		164,900,000		172,647,000
Unamortized deferred financing costs		4,608,000	4,608,000		4,608,000		5,515,000
Long-term Debt		$ 160,292,000	160,292,000		160,292,000		167,132,000
Secured credit facility, maximum borrowing capacity								250,000,000
Repayment of term loan facility					7,747,000
June 2017 Amendment to Credit Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Leverage ratio		3.89
Fixed coverage ratio		1.70
Revolving Loan Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Long-term Debt		$ 65,604,000	$ 65,604,000		$ 65,604,000		$ 83,904,000
Secured credit facility, maximum borrowing capacity								150,000,000
Revolving Loan Facility | Letter of Credit
Line of Credit Facility [Line Items]
Secured credit facility, maximum borrowing capacity								$ 25,000,000
Federal Funds Effective Rate | Revolving Loan Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Variable interest rate (percent)					0.50%
Adjusted LIBO rate | Revolving Loan Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Variable interest rate (percent)					1.00%
Floor interest rate					1.00%
Minimum | Secured Credit Facility
Line of Credit Facility [Line Items]
Blended interest rate (percent)		4.80%	4.80%		4.80%
Fixed coverage ratio		1.25
Minimum | June 2017 Amendment to Credit Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Fixed coverage ratio		1.25
Minimum | Revolving Loan Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Long-term Debt		$ 41,904,000	$ 41,904,000		$ 41,904,000
Maximum | Secured Credit Facility
Line of Credit Facility [Line Items]
Blended interest rate (percent)		4.83%	4.83%	5.00%	4.83%	5.00%
Leverage ratio		3.00
Maximum | June 2017 Amendment to Credit Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Leverage ratio		4.25
Maximum | Revolving Loan Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Long-term Debt		$ 84,904,000	$ 84,904,000		$ 84,904,000
Subsequent Event | Term Loan Facility
Line of Credit Facility [Line Items]
Balloon payment made	$ 22,500,000
Pro Forma [Member] | June 2017 Amendment to Credit Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Leverage ratio		3.52
Fourth Quarter of 2017 | Subsequent Event | Maximum | June 2017 Amendment to Credit Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Leverage ratio	3.75
At end of fiscal 2018 and thereafter | Subsequent Event | Maximum | June 2017 Amendment to Credit Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Leverage ratio	3.00
Remaining Term of Facility | Subsequent Event | Minimum | June 2017 Amendment to Credit Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Fixed coverage ratio	1.25