Segment Information - Net Income Reconciliation (Detail) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2019	Oct. 31, 2018
Segment Reconciliation [Abstract]
Total profit from reportable segments	$ 47,600	$ 47,103
Unallocated amounts:
Administrative costs	(6,709)	(6,481)
Investment and other income (expense)	1,380	(17)
Interest expense	(701)	(712)
Income before income taxes	$ 41,570	$ 39,893