Business Segment Information - Schedule of Net Sales by Product Lines and Reportable Segments (Details) - USD ($) $ in Millions	3 Months Ended												12 Months Ended
	Sep. 30, 2020	[1]	Jun. 30, 2020	[2]	Mar. 31, 2020	[3]	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	[4]	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Revenues	$ 1,784.2		$ 1,580.8		$ 1,796.7		$ 1,695.1	$ 2,195.7	$ 2,392.7	$ 1,990.2	$ 1,803.4		$ 6,856.8	$ 8,382.0	$ 7,705.5
Access Equipment
Segment Reporting Information [Line Items]
Revenues													2,505.7	4,079.7	3,776.8
Access Equipment | Aerial Work Platforms
Segment Reporting Information [Line Items]
Revenues													1,101.7	1,944.4	2,017.2
Access Equipment | Telehandlers
Segment Reporting Information [Line Items]
Revenues													680.4	1,254.9	948.9
Access Equipment | Other
Segment Reporting Information [Line Items]
Revenues													723.6	880.4	810.7
Defense
Segment Reporting Information [Line Items]
Revenues													2,260.3	2,030.3	1,827.3
Fire & Emergency
Segment Reporting Information [Line Items]
Revenues													1,138.1	1,249.8	1,053.6
Commercial
Segment Reporting Information [Line Items]
Revenues													951.3	1,020.1	1,046.8
Commercial | Concrete Placement
Segment Reporting Information [Line Items]
Revenues													403.5	439.9	491.8
Commercial | Refuse Collection
Segment Reporting Information [Line Items]
Revenues													437.2	451.9	438.3
Commercial | Other
Segment Reporting Information [Line Items]
Revenues													110.6	128.3	116.7
Corporate and Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues													1.4	2.1	1.0
Operating Segments | Access Equipment
Segment Reporting Information [Line Items]
Revenues													2,515.1	4,079.7	3,776.8
Operating Segments | Access Equipment | Aerial Work Platforms
Segment Reporting Information [Line Items]
Revenues													1,101.7	1,944.4	2,017.2
Operating Segments | Access Equipment | Telehandlers
Segment Reporting Information [Line Items]
Revenues													680.4	1,254.9	948.9
Operating Segments | Access Equipment | Other
Segment Reporting Information [Line Items]
Revenues													733.0	880.4	810.7
Operating Segments | Defense
Segment Reporting Information [Line Items]
Revenues													2,262.2	2,032.1	1,828.9
Operating Segments | Fire & Emergency
Segment Reporting Information [Line Items]
Revenues													1,147.1	1,266.1	1,069.7
Operating Segments | Commercial
Segment Reporting Information [Line Items]
Revenues													957.8	1,022.2	1,054.7
Operating Segments | Commercial | Concrete Placement
Segment Reporting Information [Line Items]
Revenues													403.5	439.9	491.8
Operating Segments | Commercial | Refuse Collection
Segment Reporting Information [Line Items]
Revenues													437.2	451.9	438.3
Operating Segments | Commercial | Other
Segment Reporting Information [Line Items]
Revenues													117.1	130.4	124.6
Corporate, Non-segment | Corporate and Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues													(25.4)	(18.1)	(24.6)
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues													(25.4)	(18.1)	(24.6)
Intersegment Eliminations | Access Equipment
Segment Reporting Information [Line Items]
Revenues													9.4
Intersegment Eliminations | Access Equipment | Other
Segment Reporting Information [Line Items]
Revenues													9.4
Intersegment Eliminations | Defense
Segment Reporting Information [Line Items]
Revenues													1.9	1.8	1.6
Intersegment Eliminations | Fire & Emergency
Segment Reporting Information [Line Items]
Revenues													9.0	16.3	16.1
Intersegment Eliminations | Commercial
Segment Reporting Information [Line Items]
Revenues													6.5	2.1	7.9
Intersegment Eliminations | Commercial | Other
Segment Reporting Information [Line Items]
Revenues													6.5	2.1	7.9
Intersegment Eliminations | Corporate and Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues													$ (26.8)	$ (20.2)	$ (25.6)

[1] ^{The fourth quarter of fiscal 2020 was impacted by restructuring-related charges of $13.0 million ($9.5 million, net of tax) in the Access Equipment, Fire & Emergency and Commercial segments and Corporate, a gain of $4.2 million ($3.2 million, net of tax) for an arbitration settlement in the Defense segment, business interruption insurance proceeds of $18.5 million ($14.2 million, net of tax) in the Commercial segment and a gain on the sale of a business of $3.1 million ($2.8 million net of tax) in the Commercial segment.}

[2] ^{The third quarter of fiscal 2020 was impacted by restructuring charges of $10.2 million ($8.4 million, net of tax) in the Access Equipment, Fire & Emergency and Commercial segments.}

[3] ^{The second quarter of fiscal 2020 was impacted by debt extinguishment costs of $8.5 million ($6.5 million, net of tax) and a tax charge of $11.4 million related to the establishment of a valuation allowance on net operating losses for an entity in Europe.}

[4] The first quarter of fiscal 2019 was impacted by tax expense related to tax reform in the U.S. of $7.0 million.