Business Segment Information - Schedule of Income (Loss) from Continuing Operations by Product Lines and Reportable Segments (Details) - USD ($) $ in Millions		3 Months Ended																12 Months Ended
		Dec. 31, 2022	[1]	Sep. 30, 2022	[2]	Jun. 30, 2022	Mar. 31, 2022	[3]	Dec. 31, 2021	Sep. 30, 2021	[4]	Jun. 30, 2021	[5]	Mar. 31, 2021	[6]	Dec. 31, 2020	[7]	Dec. 31, 2022	Sep. 30, 2021	Sep. 30, 2020
Operating income (loss):
Operating income (loss)		$ 147.0		$ 117.2		$ 76.3	$ 31.8		$ 41.6	$ 134.4		$ 213.3		$ 145.3		$ 99.1		$ 372.3	$ 592.1	$ 484.8
Interest expense, net of interest income	[8]								(11.8)									(43.9)	(44.7)	(51.8)
Miscellaneous other (expense) income	[9]								(5.6)									(52.8)	(2.1)	2.2
Income before income taxes and earnings (losses) of unconsolidated affiliates									24.2									275.6	545.3	435.2
Operating Segments | Access Equipment
Operating income (loss):
Operating income (loss)	[10]								38.2									313.2	278.2	198.2
Operating Segments | Defense
Operating income (loss):
Operating income (loss)	[11]								16.0									46.2	200.7	186.2
Operating Segments | Fire & Emergency
Operating income (loss):
Operating income (loss)									15.9									94.9	178.9	147.1
Operating Segments | Commercial
Operating income (loss):
Operating income (loss)	[12]								2.4									59.5	81.7	79.0
Corporate, Non-segment
Operating income (loss):
Operating income (loss)									$ (30.9)									$ (141.5)	$ (147.4)	$ (125.7)

[1] The fourth quarter of fiscal 2022 was impacted by a $5.6 million ($4.3 million after-tax) intangible asset impairment charge in the Defense segment and a $33.6 million ($25.7 million after-tax) pension settlement charge.

[2] The third quarter of fiscal 2022 was impacted by expense of $4.6 million to eliminate cumulative translation adjustments upon liquidation of foreign entities in the Access Equipment segment and a $2.1 million intangible asset impairment charge in the Commercial segment.

[3] The first quarter of fiscal 2022 was impacted by tax expense of $18.1 million for anti-hybrid tax on prior period income.

[4] The fourth quarter of the year ended September 30, 2021 was impacted by a tax benefit of $11.7 million for the revaluation of deferred tax liabilities and a tax benefit of $5.4 million for net operating loss carrybacks.

[5] The third quarter of the year ended September 30, 2021 was impacted a tax benefit of $69.9 million for net operating loss carrybacks and $1.3 million ($1.4 million after-tax) of restructuring-related costs in the Access Equipment segment.

[6] The second quarter of the year ended September 30, 2021 was impacted by $2.2 million ($2.5 million after-tax) of restructuring-related costs in the Access Equipment segment.

[7] The first quarter of the year ended September 30, 2021 was impacted by $8.0 million ($7.8 million after-tax) of restructuring-related costs in the Access Equipment segment.

[8] Results for the year ended September 30, 2020 include $8.5 million in debt extinguishment costs and $3.3 million of interest income from an arbitration settlement in the Defense segment.

[9] Results for fiscal 2022 include a $33.6 million charge from the settlement of a frozen pension plan. Results for the year ended September 30, 2020 include a $6.2 million gain from insurance proceeds in excess of property loss in the Commercial segment.

[10] Results for fiscal 2022 include expense of $4.6 million to eliminate cumulative translation adjustments upon liquidation of foreign entities and $2.2 million of restructuring costs. Results for the year ended September 30, 2021 include $3.1 million of restructuring costs and $7.4 million operating expenses related to restructuring plans. Results for the year ended September 30, 2020 include $10.4 million of restructuring costs and $4.7 million operating expenses related to restructuring plans.

[11] Results for fiscal 2022 include a $5.6 million intangible asset impairment charge.

[12] Results for fiscal 2022 include a $2.1 million intangible asset impairment charge. Results for the year ended September 30, 2020 include $1.5 million of restructuring costs, $4.1 million of accelerated depreciation related to restructuring actions, a gain of $12.3 million arising from a business interruption insurance recovery and a gain on the sale of a business of $3.1 million.