Commitments and Contingencies - Annual Required Payments (Details)	9 Months Ended
	Apr. 30, 2017 USD ($)
Minimum commitments under noncancelable operating leases
Remaining fiscal year	$ 1,791,000
2018	5,965,000
2019	5,056,000
2020	3,681,000
2021	2,625,000
Thereafter	3,652,000
Total	22,770,000
Total contractual obligations
Remaining fiscal year	4,550,000
2018	15,868,000
2019	153,541,000
2020	4,437,000
2021	3,285,000
Thereafter	4,674,000
Total	186,355,000
Compensation agreements
Other commitments
Remaining fiscal year	1,775,000
2018	6,034,000
2019	1,149,000
2020	498,000
2021	377,000
Thereafter	583,000
Total	10,416,000
Assumed contingent liability
Other commitments
Remaining fiscal year	19,000
2018	93,000
2019	188,000
2020	246,000
2021	280,000
Thereafter	439,000
Total	$ 1,265,000
Assumed contingent liability | Jet Prep Ltd.
Total contractual obligations
Discount rate of potential payments (as a percent)	2.50%
Assumed contingent obligation	$ 1,138,000
Other long-term obligations
Other commitments
Remaining fiscal year	88,000
2018	267,000
2019	101,000
2020	12,000
2021	3,000
Total	471,000
Credit Agreement
Maturity of the credit facility
2019	145,000,000
Total	145,000,000
Expected interest payments under the credit facility
Remaining fiscal year	877,000
2018	3,509,000
2019	2,047,000
Total	$ 6,433,000
Total contractual obligations
Weighted average interest rate on outstanding borrowings (as a percent)	2.42%