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Debt - Effective Interest Rate (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Debt
Effective interest rate including effects of interest rate swap agreements	4.6%	4.6%	4.4%
Amortization of deferred debt issuance costs	$ 18.1	$ 17.5
The 2022 Notes
Debt
Prepayment premium redemption	$ 34.5

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Amount of amortization expense attributable to debt issuance costs.

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-Publisher FASB
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-SubTopic 30
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Description of any adjustments made to the stated rate to determine the effective rate.

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