Accumulated Other Comprehensive Income (Loss) - Schedule of Changes in Accumulated Other Comprehensive Income (Loss) by Component (Details) - USD ($) $ in Millions		12 Months Ended
	Oct. 01, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of year	$ 2,513.5	$ 2,513.5
Other comprehensive income (loss) before reclassifications		(85.8)	$ 16.1	$ 46.0
Amounts reclassified from accumulated other comprehensive income (loss)		0.1	2.1	4.0
Total other comprehensive income (loss), net of tax		(85.7)	18.2	50.0
Balance at end of year		2,599.8	2,513.5
Employee Pension and Postretirement Benefits, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of year	(10.9)	(10.9)	(46.2)	(73.9)
Other comprehensive income (loss) before reclassifications		(49.5)	33.1	23.7
Amounts reclassified from accumulated other comprehensive income (loss)		0.1	2.2	4.0
Total other comprehensive income (loss), net of tax		(49.4)	35.3	27.7
Balance at end of year	(20.0)	(69.4)	(10.9)	(46.2)
Employee Pension and Postretirement Benefits, Net of Tax | Accounting Standards Update 2018-02
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	(9.1)
Cumulative Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of year	(96.2)	(96.2)	(78.6)	(101.1)
Other comprehensive income (loss) before reclassifications		(36.3)	(17.6)	22.5
Total other comprehensive income (loss), net of tax		(36.3)	(17.6)	22.5
Balance at end of year	(96.2)	(132.5)	(96.2)	(78.6)
Derivative Instruments, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of year	0.3	0.3	(0.2)
Other comprehensive income (loss) before reclassifications			0.6	(0.2)
Amounts reclassified from accumulated other comprehensive income (loss)			(0.1)
Total other comprehensive income (loss), net of tax			0.5	(0.2)
Balance at end of year	0.3	0.3	0.3	(0.2)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of year	(106.8)	(106.8)	(125.0)	(175.0)
Balance at end of year	(115.9)	$ (201.6)	$ (106.8)	$ (125.0)
Accumulated Other Comprehensive Income (Loss) | Accounting Standards Update 2018-02
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ (9.1)