Derivatives (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Fair Value, Net	$ (23.5)		$ (23.5)		$ (37,000,000.0)
Cash Flow Hedging [Member] | Other Current Liabilities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Fair Value, Net	(25.9)		(25.9)		(46,300,000)
Currency Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	8,100,000		8,100,000		64,400,000
Currency Swap [Member] | Other Current Liabilities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Fair Value, Net	(0.6)		(0.6)
Currency Swap [Member] | Other Current Assets [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Fair Value, Net					(400,000)
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	236,200,000		236,200,000		169,900,000
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	(3,000,000.0)	$ 500,000	(3.0)	$ 500,000
Derivative, Loss on Derivative	0.2		(1,000,000.0)
Derivative, Gain on Derivative		$ (100,000)		$ 1,100,000
Not Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Fair Value, Net	0.7		0.7		0
Not Designated as Hedging Instrument [Member] | Other Current Liabilities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Fair Value, Net	(3.7)		(3.7)
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	750,000,000.0		750,000,000.0
Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	198,300,000		198,300,000
Net Investment Hedging [Member] | Other Assets [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Fair Value, Net	6.0		6.0		$ 9,700,000
Net Investment Hedging [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	$ 1,300,000		$ 3,900,000