Derivative Instruments and Fair Value Measurement (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014
Derivatives, Fair Value [Line Items]
Notional values of forward exchange contracts	$ 914.6invest_DerivativeNotionalAmount
Foreign currency denominated debt designated as net investment hedges	14.0
Fair Value, Inputs, Level 2 [Member]
Assets and liabilities measured at fair value on a recurring basis
Net derivative asset / (liability) designated as hedging instruments	20.5	13.7
Net derivative asset / (liability) not designated as hedging instruments	2.1	1.7
Fair Value, Inputs, Level 2 [Member] \| Other current assets [Member]
Assets and liabilities measured at fair value on a recurring basis
Derivative assets designated as hedging instruments	24.2	13.1
Derivative assets not designated as hedging instruments	4.5	3.5
Fair Value, Inputs, Level 2 [Member] \| Other assets [Member]
Assets and liabilities measured at fair value on a recurring basis
Derivative assets designated as hedging instruments	7.1	5.0
Fair Value, Inputs, Level 2 [Member] \| Other current liabilities [Member]
Assets and liabilities measured at fair value on a recurring basis
Derivative liabilities designated as hedging instruments	(9.7)	(4.1)
Derivative liabilities not designated as hedging instruments	(2.4)	(1.8)
Fair Value, Inputs, Level 2 [Member] \| Other liabilities [Member]
Assets and liabilities measured at fair value on a recurring basis
Derivative liabilities designated as hedging instruments	(1.1)	(0.3)
Cash Flow Hedging [Member]
Derivatives, Fair Value [Line Items]
Notional values of forward exchange contracts	$ 692.5

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

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- Definition

Fair value as of the balance sheet date of all foreign currency derivative assets designated as cash flow hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959

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- Definition

Fair value as of the balance sheet date of all foreign currency derivatives designated as cash flow hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (a),(b),(c)(1)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959

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- Definition

Fair value as of the balance sheet date of all foreign currency derivative assets not designated as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959

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Fair value as of the balance sheet date of all foreign currency derivatives not designated as hedging instruments.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958

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Fair value as of the balance sheet date of all foreign currency derivative liabilities not designated as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959

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Fair value of all derivative liabilities designated as hedges of net investment in foreign operations.

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