Leases - Right of Use Asset Balance for Operating Leases Disaggregated by Segment and Type of Lease (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Lessee Lease Description [Line Items]
Right of use asset balance	$ 194.7	$ 149.0
Operating Segments | Access Equipment
Lessee Lease Description [Line Items]
Right of use asset balance	89.8	68.7
Operating Segments | Defense
Lessee Lease Description [Line Items]
Right of use asset balance	57.6	32.4
Operating Segments | Fire & Emergency
Lessee Lease Description [Line Items]
Right of use asset balance	7.9	8.7
Operating Segments | Commercial
Lessee Lease Description [Line Items]
Right of use asset balance	18.4	19.8
Corporate and Intersegment Eliminations
Lessee Lease Description [Line Items]
Right of use asset balance	21.0	19.4
Real Estate Leases
Lessee Lease Description [Line Items]
Right of use asset balance	174.2	121.0
Real Estate Leases | Operating Segments | Access Equipment
Lessee Lease Description [Line Items]
Right of use asset balance	84.3	61.4
Real Estate Leases | Operating Segments | Defense
Lessee Lease Description [Line Items]
Right of use asset balance	55.6	28.2
Real Estate Leases | Operating Segments | Fire & Emergency
Lessee Lease Description [Line Items]
Right of use asset balance	6.2	6.5
Real Estate Leases | Operating Segments | Commercial
Lessee Lease Description [Line Items]
Right of use asset balance	15.9	17.9
Real Estate Leases | Corporate and Intersegment Eliminations
Lessee Lease Description [Line Items]
Right of use asset balance	12.2	7.0
Equipment Leases
Lessee Lease Description [Line Items]
Right of use asset balance	20.5	28.0
Equipment Leases | Operating Segments | Access Equipment
Lessee Lease Description [Line Items]
Right of use asset balance	5.5	7.3
Equipment Leases | Operating Segments | Defense
Lessee Lease Description [Line Items]
Right of use asset balance	2.0	4.2
Equipment Leases | Operating Segments | Fire & Emergency
Lessee Lease Description [Line Items]
Right of use asset balance	1.7	2.2
Equipment Leases | Operating Segments | Commercial
Lessee Lease Description [Line Items]
Right of use asset balance	2.5	1.9
Equipment Leases | Corporate and Intersegment Eliminations
Lessee Lease Description [Line Items]
Right of use asset balance	$ 8.8	$ 12.4