Restructuring Charges (Details) - USD ($)	3 Months Ended		9 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2017	Apr. 30, 2016	Jul. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 0	$ 4,100,000	$ 0	$ 12,600,000
Restructuring reserve	$ 0		$ 0		$ 0
Cost of Sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges		800,000		4,900,000
Operating Expense
Restructuring Cost and Reserve [Line Items]
Restructuring charges		3,300,000		7,700,000
Engine Products
Restructuring Cost and Reserve [Line Items]
Restructuring charges		1,200,000		7,200,000
Industrial Filtration Solutions Products
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 2,900,000		$ 5,400,000