Segment Information - Net Income Reconciliation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total profit from reportable segments	$ 156,126	$ 143,068	$ 118,736
Unallocated amounts:
Administrative costs	25,111	25,190	19,742
Restructuring charges	0	0	16,821
Impairment charges	0	0	46,867
Investment and other income	(1,121)	709	(845)
Interest Expense	5,504	7,824	11,156
Earnings from continuing operations before income taxes	126,632	109,345	24,995
Workplace Safety
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total profit from reportable segments	25,554	30,792	29,344
Unallocated amounts:
Impairment charges			39
Identification Solutions
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total profit from reportable segments	$ 130,572	$ 112,276	89,392
Unallocated amounts:
Impairment charges			$ 8