Accumulated Other Comprehensive Income (Loss) - Schedule of Changes in Accumulated Other Comprehensive Income (Loss) by Component (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Sep. 30, 2021
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of year		$ 3,185.7
Total other comprehensive income, net of tax	$ 2.4	20.3	$ 36.3	$ 67.4
Balance at end of year		3,705.3	3,185.7
Employee Pension and Postretirement Benefits, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of year	(34.2)	31.1	(25.6)	(95.9)
Other comprehensive income (loss) before reclassifications	8.2	3.5	29.3	57.1
Amounts reclassified from accumulated other comprehensive income (loss)	0.4	(1.6)	27.4	4.6
Total other comprehensive income, net of tax	8.6	1.9	56.7	61.7
Balance at end of year	(25.6)	33.0	31.1	(34.2)
Cumulative Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of year	(98.3)	(131.6)	(105.2)	(102.1)
Other comprehensive income (loss) before reclassifications	(6.9)	24.2	(31.0)	3.8
Amounts reclassified from accumulated other comprehensive income (loss)		2.9	4.6
Total other comprehensive income, net of tax	(6.9)	27.1	(26.4)	3.8
Balance at end of year	(105.2)	(104.5)	(131.6)	(98.3)
Derivative Instruments, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of year	1.5	8.2	2.2	(0.4)
Other comprehensive income (loss) before reclassifications	0.9	(0.5)	6.2	1.5
Amounts reclassified from accumulated other comprehensive income (loss)	(0.2)	(8.2)	(0.2)	0.4
Total other comprehensive income, net of tax	0.7	(8.7)	6.0	1.9
Balance at end of year	2.2	(0.5)	8.2	1.5
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of year	(131.0)	(92.3)	(128.6)	(198.4)
Other comprehensive income (loss) before reclassifications	2.2	27.2	4.5	62.4
Amounts reclassified from accumulated other comprehensive income (loss)	0.2	(6.9)	31.8	5.0
Total other comprehensive income, net of tax	2.4	20.3	36.3	67.4
Balance at end of year	$ (128.6)	$ (72.0)	$ (92.3)	$ (131.0)