Segment Reporting (Summary of Segment Detail) (Details) - USD ($) $ in Millions	3 Months Ended
	Oct. 31, 2020	Oct. 31, 2019
Segment Reporting Information
Net sales	$ 636.6	$ 672.7
Earnings before income taxes	82.2	86.6
Operating Segments | Engine Products segment
Segment Reporting Information
Net sales	436.2	459.2
Earnings before income taxes	60.4	62.4
Operating Segments | Engine Products segment | Off-Road
Segment Reporting Information
Net sales	64.8	68.6
Operating Segments | Engine Products segment | On-Road
Segment Reporting Information
Net sales	32.0	40.7
Operating Segments | Engine Products segment | Aftermarket
Segment Reporting Information
Net sales	317.0	319.4
Operating Segments | Engine Products segment | Aerospace and Defense
Segment Reporting Information
Net sales	22.4	30.5
Operating Segments | Industrial Products segment
Segment Reporting Information
Net sales	200.4	213.5
Earnings before income taxes	27.5	29.5
Operating Segments | Industrial Products segment | Industrial Filtration Solutions
Segment Reporting Information
Net sales	135.6	149.0
Operating Segments | Industrial Products segment | Gas Turbine Systems
Segment Reporting Information
Net sales	23.0	20.7
Operating Segments | Industrial Products segment | Special Applications
Segment Reporting Information
Net sales	41.8	43.8
Corporate and Unallocated
Segment Reporting Information
Earnings before income taxes	$ (5.7)	$ (5.3)