Segment Information - Net Income Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Document Fiscal Year Focus			2020
Segment profit	$ 46,110	$ 42,518	$ 93,710	$ 89,621
Unallocated amounts:
Administrative costs	(4,866)	(6,488)	(11,575)	(12,969)
Investment and other income	1,760	1,377	3,140	1,360
Interest expense	(647)	(717)	(1,348)	(1,429)
Income before income taxes	$ 42,357	$ 36,690	$ 83,927	$ 76,583