Segment Information - Net Income Reconciliation (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2018	Apr. 30, 2017
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total profit from reportable segments	$ 44,507	$ 37,753	$ 127,933	$ 112,291
Unallocated amounts:
Administrative costs	(6,798)	(6,203)	(20,017)	(17,571)
Investment and other income	31	453	1,303	560
Interest expense	(761)	(1,375)	(2,453)	(4,565)
Earnings before income taxes	$ 36,979	$ 30,628	$ 106,766	$ 90,715