Segment Reporting (Net Sales by Product Within Engine Products Segment and Industrial Products Segment) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Jul. 31, 2020	Apr. 30, 2020	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018
Segment Reporting Information
Net sales	$ 617.4	$ 629.7	$ 662.0	$ 672.7	$ 726.9	$ 712.8	$ 703.7	$ 701.4	$ 2,581.8	$ 2,844.9	$ 2,734.2
Engine Products | Off-Road
Segment Reporting Information
Net sales									256.5	315.1	327.4
Engine Products | On-Road
Segment Reporting Information
Net sales									124.4	179.8	154.2
Engine Products | Aftermarket
Segment Reporting Information
Net sales									1,228.9	1,315.3	1,261.9
Engine Products | Aerospace and Defense
Segment Reporting Information
Net sales									117.7	115.8	105.5
Industrial Products | Industrial Filtration Solutions
Segment Reporting Information
Net sales									581.2	641.8	594.3
Industrial Products | Gas Turbine Systems
Segment Reporting Information
Net sales									101.6	106.3	115.5
Industrial Products | Special Applications
Segment Reporting Information
Net sales									$ 171.5	$ 170.8	$ 175.4