Accumulated Other Comprehensive (Loss) Income (Details) - USD ($)	12 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Components and changes in accumulated other comprehensive (loss) income
Balance	$ 406,633,000	$ 365,246,000	$ 321,132,000
Other comprehensive loss	(13,019,000)	(8,328,000)	(1,425,000)
Reclassification adjustment to loss on sale of business for foreign currency translation gain included in net income during the period		2,206,000
Income tax effect on reclassification adjustments	33,978,000	28,238,000	25,346,000
Balance	454,370,000	406,633,000	365,246,000
Accumulated Other Comprehensive Income
Components and changes in accumulated other comprehensive (loss) income
Balance	1,224,000	9,552,000	10,977,000
Other comprehensive loss	(13,019,000)	(8,328,000)	(1,425,000)
Other comprehensive income before reclassifications, net of tax		(7,064,000)
Other comprehensive loss before reclassifications, before tax			(1,575,000)
Income tax effect on other comprehensive loss before reclassifications			17,000
Balance	(11,795,000)	1,224,000	9,552,000
Accumulated Other Comprehensive Income | Reclassification adjustments
Components and changes in accumulated other comprehensive (loss) income
Reclassification adjustment to loss on sale of business for foreign currency translation gain included in net income during the period		(1,264,000)
Reclassification adjustments to interest expense for losses on interest rate swaps included in net income during the period			96,000
Reclassification adjustment for ineffective hedge on interest rate swap included in net income during the period			113,000
Income tax effect on reclassification adjustments			(76,000)
Foreign Currency Translation Adjustments
Components and changes in accumulated other comprehensive (loss) income
Balance	1,224,000	9,552,000	11,080,000
Other comprehensive loss	(13,019,000)
Other comprehensive income before reclassifications, net of tax		(7,064,000)
Other comprehensive loss before reclassifications, before tax			(1,528,000)
Balance	$ (11,795,000)	1,224,000	9,552,000
Foreign Currency Translation Adjustments | Reclassification adjustments
Components and changes in accumulated other comprehensive (loss) income
Reclassification adjustment to loss on sale of business for foreign currency translation gain included in net income during the period		$ (1,264,000)
Interest Rate Swap Agreements.
Components and changes in accumulated other comprehensive (loss) income
Balance			(103,000)
Other comprehensive loss before reclassifications, before tax			(47,000)
Income tax effect on other comprehensive loss before reclassifications			17,000
Interest Rate Swap Agreements. | Interest rate swap agreements | Reclassification adjustments
Components and changes in accumulated other comprehensive (loss) income
Reclassification adjustments to interest expense for losses on interest rate swaps included in net income during the period			96,000
Reclassification adjustment for ineffective hedge on interest rate swap included in net income during the period			113,000
Income tax effect on reclassification adjustments			$ (76,000)