Segment Information - Net Income Reconciliation (Detail) - USD ($)	12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total profit from reportable segments	$ 175,123,000	$ 156,126,000	$ 143,068,000
Unallocated amounts:
Administrative costs	27,093,000	25,111,000	25,190,000
Gain (Loss) on Disposition of Business	(4,666,000)	0	0
Investment and other income	(2,487,000)	(1,121,000)	709,000
Interest Expense	3,168,000	5,504,000	7,824,000
Earnings before income taxes	152,015,000	126,632,000	109,345,000
Workplace Safety
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total profit from reportable segments	31,712,000	25,554,000	30,792,000
Identification Solutions
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total profit from reportable segments	$ 143,411,000	$ 130,572,000	$ 112,276,000