Revenue (Schedule of Product and Market Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Net sales	$ 2,887.0	$ 2,959.7	$ 3,050.1
North America
Disaggregation of Revenue [Line Items]
Net sales	1,824.2	1,882.1	1,932.0
Modern Markets
Disaggregation of Revenue [Line Items]
Net sales	498.8	495.9	515.9
Developing Markets
Disaggregation of Revenue [Line Items]
Net sales	378.4	391.6	400.9
Distributor Markets
Disaggregation of Revenue [Line Items]
Net sales	185.6	190.1	201.3
Batteries
Disaggregation of Revenue [Line Items]
Net sales	2,161.4	2,233.9	2,298.2
Auto Care
Disaggregation of Revenue [Line Items]
Net sales	627.5	614.8	622.8
Lights
Disaggregation of Revenue [Line Items]
Net sales	$ 98.1	$ 111.0	$ 129.1