Property, Plant and Equipment - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Millions	Jun. 30, 2020	Sep. 30, 2019
Property, plant and equipment at cost:
Property, plant and equipment, at cost	$ 17,797.2	$ 17,461.3
Less: accumulated depreciation, depletion and amortization	(6,874.6)	(6,271.8)
Property, plant and equipment, net	10,922.6	11,189.5
Land and Buildings [Member]
Property, plant and equipment at cost:
Property, plant and equipment, at cost	2,507.3	2,442.3
Machinery and Equipment [Member]
Property, plant and equipment at cost:
Property, plant and equipment, at cost	15,044.2	14,743.6
Forestlands and Mineral Rights [Member]
Property, plant and equipment at cost:
Property, plant and equipment, at cost	114.1	144.0
Transportation Equipment [Member]
Property, plant and equipment at cost:
Property, plant and equipment, at cost	28.8	31.2
Leasehold Improvements [Member]
Property, plant and equipment at cost:
Property, plant and equipment, at cost	$ 102.8	$ 100.2