Borrowings and Credit Arrangements - Company's Borrowings (Detail) - USD ($) $ in Millions	Mar. 31, 2018	Sep. 30, 2017
Debt Instrument [Line Items]
Current portion of long-term debt	$ 611.5	$ 1,150.8
Convertible Notes	200.5	484.5
Total long-term debt obligations	2,739.2	2,172.1
Total debt obligations	3,350.7	3,322.9
Term Loan
Debt Instrument [Line Items]
Current portion of long-term debt	56.0	121.3
Long term debt obligations. excluding convertible notes	1,412.3	1,190.5
Revolver
Debt Instrument [Line Items]
Current portion of long-term debt	155.0	345.0
Securitization Program
Debt Instrument [Line Items]
Current portion of long-term debt	200.0	200.0
2022 Senior Notes
Debt Instrument [Line Items]
Long term debt obligations. excluding convertible notes	0.0	981.6
2025 Senior Notes
Debt Instrument [Line Items]
Long term debt obligations. excluding convertible notes	934.1	0.0
2028 Senior Notes
Debt Instrument [Line Items]
Long term debt obligations. excluding convertible notes	$ 392.8	$ 0.0

Long term debt obligations without convertible notes.

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Carrying value as of the balance sheet date of the portion of long-term debt due within one year or the operating cycle if longer identified as Convertible Notes Payable. Convertible Notes Payable is a written promise to pay a note which can be exchanged for a specified amount of another, related security, at the option of the issuer and the holder.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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+ References

No definition available.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 210
-Section S99
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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

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