Segment Information - Net Income Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2019	Apr. 30, 2018
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment profit	$ 45,991	$ 44,507	$ 135,612	$ 127,933
Unallocated amounts:
Administrative costs	(6,370)	(6,798)	(19,339)	(20,017)
Investment and other income	2,065	31	3,425	1,303
Interest expense	(708)	(761)	(2,137)	(2,453)
Income before income taxes	$ 40,978	$ 36,979	$ 117,561	$ 106,766