Summary of Significant Accounting Policies - Summary of the Impacts on Previously Issued Consolidated Financial Statements (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended																12 Months Ended
	Oct. 01, 2019	Dec. 31, 2022		Sep. 30, 2022	[2]	Jun. 30, 2022	Mar. 31, 2022	[3]	Dec. 31, 2021	Sep. 30, 2021		Jun. 30, 2021	[5]	Mar. 31, 2021	[6]	Dec. 31, 2020	[7]	Dec. 31, 2022	Sep. 30, 2021	Sep. 30, 2020
Summary Of Significant Accounting Policies [Line Items]
Cost of sales									$ 1,596.4									$ 7,227.6	$ 6,469.1	$ 5,740.4
Gross income		$ 315.0	[1]	$ 288.6		$ 247.0	$ 203.8		195.3	$ 308.7	[4]	$ 394.1		$ 319.6		$ 245.8		1,054.4	1,268.2	1,116.4
Operating income		147.0	[1]	117.2		76.3	31.8		41.6	134.4	[4]	213.3		145.3		99.1		372.3	592.1	484.8
Income before income taxes and losses of unconsolidated affiliates									24.2									275.6	545.3	435.2
Provision for income taxes									1.2									97.5	36.4	111.9
Income before earnings (losses) of unconsolidated affiliates									23.0									178.1	508.9	323.3
Net income		75.1	[1]	$ 66.9		$ 32.1	$ (0.2)		$ 24.2	112.9	[4]	$ 221.0		$ 103.0		$ 72.0		$ 173.9	$ 508.9	$ 321.5
Basic Earnings per share									$ 0.36									$ 2.65	$ 7.43	$ 4.72
Diluted Earnings per share									$ 0.36									$ 2.63	$ 7.35	$ 4.67
Inventories, net		1,865.6							$ 1,550.4	1,411.5								$ 1,865.6	$ 1,411.5
Total current assets		4,532.1							4,282.3	4,562.0								4,532.1	4,562.0
Long-term net deferred tax asset		134.8							71.7	8.3								134.8	8.3
Total assets		7,729.0							6,849.7	7,035.7								7,729.0	7,035.7
Income taxes payable		100.3							222.1	64.9								100.3	64.9
Retained earnings	$ 76.6	3,315.0							3,238.5	3,239.2								3,315.0	3,239.2
Total shareholders' equity		3,185.7							3,204.3	3,357.7								3,185.7	3,357.7
Total liabilities and shareholders' equity		7,729.0							6,849.7	7,035.7								7,729.0	7,035.7
Deferred income taxes									(179.5)									(53.5)	99.8	$ 21.5
Increase (decrease) in income taxes payable									190.6									71.8	(156.7)	(52.1)
(Increase) decrease in inventories	$ 100.6								139.0									330.8	(199.3)	242.8
Other Long Term Liabilities
Summary Of Significant Accounting Policies [Line Items]
Long-term net deferred tax liability										108.1									108.1
As Computed under LIFO
Summary Of Significant Accounting Policies [Line Items]
Cost of sales																		7,285.5
Gross income																		996.5
Operating income																		314.4
Income before income taxes and losses of unconsolidated affiliates																		217.7
Provision for income taxes																		83.7
Income before earnings (losses) of unconsolidated affiliates																		134.0
Net income																		$ 129.8
Basic Earnings per share																		$ 1.98
Diluted Earnings per share																		$ 1.96
Inventories, net		1,640.0																$ 1,640.0
Total current assets		4,306.5																4,306.5
Long-term net deferred tax asset		164.3																164.3
Total assets		7,532.9																7,532.9
Income taxes payable		76.2																76.2
Retained earnings		3,143.0																3,143.0
Total shareholders' equity		3,013.7																3,013.7
Total liabilities and shareholders' equity		7,532.9																7,532.9
Deferred income taxes																		(43.2)
Increase (decrease) in income taxes payable																		47.7
(Increase) decrease in inventories																		(272.9)
Adjustments
Summary Of Significant Accounting Policies [Line Items]
Cost of sales																		(57.9)
Gross income																		57.9
Operating income																		57.9
Income before income taxes and losses of unconsolidated affiliates																		57.9
Provision for income taxes																		13.8
Income before earnings (losses) of unconsolidated affiliates																		44.1
Net income																		$ 44.1
Basic Earnings per share																		$ 0.67
Diluted Earnings per share																		$ 0.67
Inventories, net		225.6																$ 225.6
Total current assets		225.6																225.6
Long-term net deferred tax asset		(29.5)																(29.5)
Total assets		196.1																196.1
Income taxes payable		24.1																24.1
Retained earnings		172.0																172.0
Total shareholders' equity		172.0																172.0
Total liabilities and shareholders' equity		196.1																196.1
Deferred income taxes																		(10.3)
Increase (decrease) in income taxes payable																		24.1
(Increase) decrease in inventories																		(57.9)
As Reported under FIFO
Summary Of Significant Accounting Policies [Line Items]
Cost of sales																		7,227.6
Gross income																		1,054.4
Operating income																		372.3
Income before income taxes and losses of unconsolidated affiliates																		275.6
Provision for income taxes																		97.5
Income before earnings (losses) of unconsolidated affiliates																		178.1
Net income																		$ 173.9
Basic Earnings per share																		$ 2.65
Diluted Earnings per share																		$ 2.63
Inventories, net		1,865.6																$ 1,865.6
Total current assets		4,532.1																4,532.1
Long-term net deferred tax asset		134.8																134.8
Total assets		7,729.0																7,729.0
Income taxes payable		100.3																100.3
Retained earnings		3,315.0																3,315.0
Total shareholders' equity		3,185.7																3,185.7
Total liabilities and shareholders' equity		$ 7,729.0																7,729.0
Deferred income taxes																		(53.5)
Increase (decrease) in income taxes payable																		71.8
(Increase) decrease in inventories																		$ (330.8)
As Previously Reported
Summary Of Significant Accounting Policies [Line Items]
Cost of sales									1,620.0										6,516.5	5,736.5
Gross income									171.7										1,220.8	1,120.3
Operating income									18.0										544.7	488.7
Income before income taxes and losses of unconsolidated affiliates									0.6										497.9	439.1
Provision for income taxes									(4.4)										25.2	112.8
Income before earnings (losses) of unconsolidated affiliates									5.0										472.7	326.3
Net income									$ 6.2										$ 472.7	$ 324.5
Basic Earnings per share									$ 0.09										$ 6.90	$ 4.76
Diluted Earnings per share									$ 0.09										$ 6.83	$ 4.72
Inventories, net									$ 1,382.7	1,267.4									$ 1,267.4
Total current assets									4,114.6	4,417.9									4,417.9
Long-term net deferred tax asset									111.5
Total assets									6,721.8	6,891.6									6,891.6
Retained earnings									3,110.6	3,129.3									3,129.3
Total shareholders' equity									3,076.4	3,247.8									3,247.8
Total liabilities and shareholders' equity									6,721.8	6,891.6									6,891.6
Deferred income taxes									(185.1)										88.6	$ 22.4
(Increase) decrease in inventories									115.4										(246.7)	246.7
As Previously Reported | Other Long Term Liabilities
Summary Of Significant Accounting Policies [Line Items]
Long-term net deferred tax liability										73.9									73.9
Adjustments
Summary Of Significant Accounting Policies [Line Items]
Cost of sales									(23.6)										(47.4)	3.9
Gross income									23.6										47.4	(3.9)
Operating income									23.6										47.4	(3.9)
Income before income taxes and losses of unconsolidated affiliates									23.6										47.4	(3.9)
Provision for income taxes									5.6										11.2	(0.9)
Income before earnings (losses) of unconsolidated affiliates									18.0										36.2	(3.0)
Net income									$ 18.0										$ 36.2	$ (3.0)
Basic Earnings per share									$ 0.27										$ 0.53	$ (0.04)
Diluted Earnings per share									$ 0.27										$ 0.52	$ (0.05)
Inventories, net									$ 167.7	144.1									$ 144.1
Total current assets									167.7	144.1									144.1
Long-term net deferred tax asset									(39.8)
Total assets									127.9	144.1									144.1
Retained earnings									127.9	109.9									109.9
Total shareholders' equity									127.9	109.9									109.9
Total liabilities and shareholders' equity									127.9	144.1									144.1
Deferred income taxes									5.6										11.2	$ (0.9)
(Increase) decrease in inventories									$ 23.6										47.4	$ (3.9)
Adjustments | Other Long Term Liabilities
Summary Of Significant Accounting Policies [Line Items]
Long-term net deferred tax liability										$ 34.2									$ 34.2

[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.