Face (par) amount of debt instrument at time of issuance.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Nominal or face amount used to calculate payment on derivative.

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The estimated net amount of unrealized gains or losses on foreign currency cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

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Maximum length of time over which the entity is hedging its exposure to the variability in future cash flows for forecasted transactions, excluding those forecasted transactions related to the payment of variable interest on existing financial instruments, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Derivative Instruments - Narrative (Details) - USD ($)	12 Months Ended
Derivative Instruments - Narrative (Details) - USD ($)	Sep. 30, 2019	Feb. 28, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Maximum length of time hedged in cash flow hedge	2 years
Net unrealized gains on cash flow hedges to be reclassified into earnings during the next 12 months	$ 15,700,000
Forward exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
U.S. dollar-equivalent gross notional amount	1,202,400,000
Forward exchange contracts \| Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
U.S. dollar-equivalent gross notional amount	318,100,000
Aggregate principal amount of notes issued
Derivative Instruments, Gain (Loss) [Line Items]
Long-term debt		$ 600,000,000.0
Cash Flow Hedging \| Forward exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
U.S. dollar-equivalent gross notional amount	774,000,000.0
Net Investment Hedging \| Forward exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
U.S. dollar-equivalent gross notional amount	110,300,000
Fair Value Hedging \| Interest rate swap contracts
Derivative Instruments, Gain (Loss) [Line Items]
U.S. dollar-equivalent gross notional amount	$ 600,000,000.0