Secured Credit Facility (Details)		1 Months Ended	3 Months Ended		9 Months Ended
	Apr. 30, 2018 USD ($)	Jun. 30, 2017 USD ($) $ / shares	Apr. 30, 2018 USD ($)	Apr. 30, 2017 USD ($)	Apr. 30, 2018 USD ($)	Apr. 30, 2017 USD ($)	Jul. 31, 2017 USD ($)	Feb. 23, 2016 USD ($)
Line of Credit Facility [Line Items]
Current portion of long-term debt	$ 17,211,000		$ 17,211,000		$ 17,211,000		$ 15,494,000
Non-current portion of long-term debt, net	161,856,000		161,856,000		161,856,000		176,228,000
Repayment of term loan facility					14,657,000	$ 7,747,000
Secured Credit Facility
Line of Credit Facility [Line Items]
Long-term Debt	179,067,000		179,067,000		179,067,000		191,722,000
Current portion of long-term debt	17,211,000		17,211,000		17,211,000		15,494,000
Non-current portion of long-term debt, net	161,856,000		161,856,000		161,856,000		176,228,000
Secured credit facility, maximum borrowing capacity								$ 400,000,000
Interest expense including amortization of deferred financing costs			$ 2,351,000	$ 2,641,000	$ 7,166,000	$ 8,524,000
Blended interest rate (percent)			5.49%	4.83%	5.29%	4.80%
Outstanding standby letters of credit at period end	3,268,000		$ 3,268,000		$ 3,268,000
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
Leverage ratio	2.43
Fixed charge coverage ratio	2.36
Targeted quarterly dividend per share | $ / shares		$ 0.10
Term Loan Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Long-term debt, gross	$ 124,423,000		124,423,000		124,423,000		139,080,000
Unamortized deferred financing costs	3,760,000		3,760,000		3,760,000		4,763,000
Long-term Debt	120,663,000		120,663,000		120,663,000		134,317,000
Secured credit facility, maximum borrowing capacity								250,000,000
Repayment of term loan facility					14,657,000	$ 7,747,000
Revolving Loan Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Long-term Debt	$ 58,404,000		58,404,000		$ 58,404,000		$ 57,405,000
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]
Fixed charge 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]
Leverage ratio	3.1
Maximum | Revolving Loan Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Long-term Debt	$ 66,804,000		$ 66,804,000		$ 66,804,000
Fourth quarter of fiscal 2018 and thereafter | Maximum | Secured Credit Facility
Line of Credit Facility [Line Items]
Leverage ratio	3.00
Due by February 23, 2021 | Term Loan Facility | Secured Credit Facility
Line of Credit Facility [Line Items]
Balloon payment to be made		$ 22,500,000