Contingent Liabilities and Environmental Reserves - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Oct. 31, 2016	Oct. 31, 2015
Site Contingency [Line Items]
Environmental liability reserves	$ 6.8	$ 8.2
European Drum Facilities
Site Contingency [Line Items]
Environmental liability reserves	3.9	4.3
Life Cycle Management and Recycling Facilities
Site Contingency [Line Items]
Environmental liability reserves	0.3	2.0
Sites Owned by Others
Site Contingency [Line Items]
Environmental liability reserves	1.7	0.8
Other Facilities
Site Contingency [Line Items]
Environmental liability reserves	0.9	$ 1.1
Decrease in environmental reserve due to the divestment of subsidiary	$ 1.4