Derivative Instruments and Fair Value Measurement (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Sep. 30, 2013
Derivatives, Fair Value [Line Items]
Notional values of forward exchange contracts	$ 885.5
Foreign currency denominated debt designated as net investment hedges	14.9
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	(4.8)	(4.9)
Net derivative asset / (liability) not designated as hedging instruments	6.0	3.8
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	7.3	4.8
Derivative assets not designated as hedging instruments	8.5	4.9
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	0.4	0.2
Derivative assets not designated as hedging instruments	0	0.7
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	(10.5)	(8.3)
Derivative liabilities not designated as hedging instruments	(2.5)	(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	(2.0)	(1.6)
Cash Flow Hedging [Member]
Derivatives, Fair Value [Line Items]
Notional values of forward exchange contracts	$ 638.5