Commitments and Contingencies (Details 2) (USD $)	12 Months Ended
	Jul. 31, 2013 item	Jul. 31, 2012	Jul. 31, 2011
Operating Leases
Number of significant leases that contain escalation clauses	5
Rent expense	$ 4,147,000	$ 4,104,000	$ 3,924,000
Building | Water Purification and Filtration
Operating Leases
Number of significant leases that contain escalation clauses	2
Building | Water Purification and Filtration | Pennsylvania | Fiscal 2014
Operating Leases
Monthly base rent	16,200
Building | Water Purification and Filtration | Pennsylvania | Fiscal 2025
Operating Leases
Monthly base rent	20,100
Building | Water Purification and Filtration | Toronto, Ontario | Fiscal 2014
Operating Leases
Monthly base rent	16,000
Building | Water Purification and Filtration | Toronto, Ontario | Fiscal 2015
Operating Leases
Monthly base rent	16,000
Building | Healthcare Disposables
Operating Leases
Number of significant leases that contain escalation clauses	2
Building | Healthcare Disposables | Pennsylvania
Operating Leases
Number of significant leases that contain escalation clauses	1
Building | Healthcare Disposables | Pennsylvania | Fiscal 2014
Operating Leases
Monthly base rent	18,600
Building | Healthcare Disposables | Pennsylvania | Fiscal 2024
Operating Leases
Monthly base rent	20,800
Building | Healthcare Disposables | California | Fiscal 2014
Operating Leases
Monthly base rent	18,800
Building | Healthcare Disposables | California | Fiscal 2015
Operating Leases
Monthly base rent	19,300
Building | Specialty Packaging business
Operating Leases
Number of significant leases that contain escalation clauses	1
Building | Specialty Packaging business | Alberta | Fiscal 2016
Operating Leases
Monthly base rent	8,000
Building | Specialty Packaging business | Alberta | Fiscal 2021
Operating Leases
Monthly base rent	$ 9,000