Revenue - Disaggregation of Revenue by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Oct. 31, 2018	Oct. 31, 2017
Disaggregation of Revenue [Line Items]
Total net sales	$ 701.4	$ 644.8
Engine Products segment
Disaggregation of Revenue [Line Items]
Total net sales	480.9	442.1
Engine Products segment | Off-Road
Disaggregation of Revenue [Line Items]
Total net sales	76.2	75.0
Engine Products segment | On-Road
Disaggregation of Revenue [Line Items]
Total net sales	45.9	33.3
Engine Products segment | On-Road
Disaggregation of Revenue [Line Items]
Total net sales	331.2	309.1
Engine Products segment | Aerospace and Defense
Disaggregation of Revenue [Line Items]
Total net sales	27.6	24.7
Industrial Products segment
Disaggregation of Revenue [Line Items]
Total net sales	220.5	202.7
Industrial Products segment | Industrial Filtration Solutions
Disaggregation of Revenue [Line Items]
Total net sales	149.4	134.5
Industrial Products segment | Gas Turbine Systems
Disaggregation of Revenue [Line Items]
Total net sales	25.5	26.3
Industrial Products segment | Special Applications
Disaggregation of Revenue [Line Items]
Total net sales	$ 45.6	$ 41.9