Segment Reporting (Summary of Segment Detail) (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
Equity earnings in unconsolidated affiliates									5.2	2.2	3.6
Earnings (loss) before income taxes									335.2	375.2	363.6
Equity investments in unconsolidated affiliates	21.7				23.0				21.7	23.0	21.7
Operating Segments | Engine Products
Segment Reporting Information
Net sales									1,727.5	1,926.0	1,849.0
Equity earnings in unconsolidated affiliates									4.7	2.1	3.7
Earnings (loss) before income taxes									229.3	254.6	258.8
Equity investments in unconsolidated affiliates	21.7				19.0				21.7	19.0	17.8
Operating Segments | Industrial Products
Segment Reporting Information
Net sales									854.3	918.9	885.2
Equity earnings in unconsolidated affiliates									0.5	0.1	(0.1)
Earnings (loss) before income taxes									124.9	140.1	135.5
Equity investments in unconsolidated affiliates	0.0				4.0				0.0	4.0	3.9
Corporate and Unallocated
Segment Reporting Information
Net sales									0.0	0.0	0.0
Equity earnings in unconsolidated affiliates									0.0	0.0	0.0
Earnings (loss) before income taxes									(19.0)	(19.5)	(30.7)
Equity investments in unconsolidated affiliates	$ 0.0				$ 0.0				$ 0.0	$ 0.0	$ 0.0