Leases (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Leases [Abstract]
Capital leases, plant and equipment	$ 21.6	$ 22.3
Capital leases, accumulated depreciation	6.1	5.3
Operating leases, rent expense	82.7	65.8	$ 67.6
Capital leases, present value future lease payments	10.5
Lessor, total lease payments collected	182.7	183.6	186.0
Lessor, payments reducing lease receivable	97.4	92.2	$ 85.5
Property, Plant and Equipment [Line Items]
Plant and equipment, at cost	21,490.2	19,547.8
Accumulated depreciation	11,566.5	$ 11,107.6
Assets Leased to Others
Property, Plant and Equipment [Line Items]
Plant and equipment, at cost	2,400.0
Accumulated depreciation	$ 400.0