Segment Information - Net Income Reconciliation (Detail) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2020	Oct. 31, 2019
Segment Reconciliation [Abstract]
Total profit from reportable segments	$ 48,267	$ 47,600
Unallocated amounts:
Administrative costs	(6,079)	(6,709)
Investment and other income	155	1,380
Interest expense	(106)	(701)
Income before income taxes and losses of unconsolidated affiliate	$ 42,237	$ 41,570