Business Segment Information - Identifiable Assets (Details) - USD ($) $ in Millions	Mar. 31, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Assets	$ 8,317.7	$ 7,264.7
Corporate
Segment Reporting Information [Line Items]
Assets	3,172.7	2,692.0
Intelligent Devices | Operating Segments
Segment Reporting Information [Line Items]
Assets	1,766.9	1,585.0
Software & Control | Operating Segments
Segment Reporting Information [Line Items]
Assets	1,481.2	1,072.7
Lifecycle Services | Operating Segments
Segment Reporting Information [Line Items]
Assets	$ 1,896.9	$ 1,915.0