Segment Information - Net Income Reconciliation (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2017	Apr. 30, 2016
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total profit from reportable segments	$ 37,753	$ 37,910	$ 112,291	$ 102,075
Unallocated amounts:
Administrative costs	(6,203)	(7,126)	(17,571)	(17,600)
Investment and other income	453	721	560	(1,030)
Interest expense	(1,375)	(1,838)	(4,565)	(6,119)
Earnings before income taxes	$ 30,628	$ 29,667	$ 90,715	$ 77,326