Derivative Instruments and Fair Value Measurement (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013
Derivatives, Fair Value [Line Items]
Notional values of forward exchange contracts	$ 886.4
Foreign currency denominated debt designated as net investment hedges	14.7
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	(3.8)	(4.9)
Net derivative asset / (liability) not designated as hedging instruments	6.1	3.8
Fair Value, Inputs, Level 2 [Member] | Other current assets [Member]
Assets and liabilities measured at fair value on a recurring basis
Derivatives assets designated as hedging instruments	6.5	4.8
Derivatives assets not designated as hedging instruments	7.8	4.9
Fair Value, Inputs, Level 2 [Member] | Other assets [Member]
Assets and liabilities measured at fair value on a recurring basis
Derivatives assets designated as hedging instruments	0.3	0.2
Derivatives 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
Derivatives liabilities designated as hedging instruments	(8.8)	(8.3)
Derivatives liabilities not designated as hedging instruments	(1.7)	(1.8)
Fair Value, Inputs, Level 2 [Member] | Other liabilities [Member]
Assets and liabilities measured at fair value on a recurring basis
Derivatives liabilities designated as hedging instruments	(1.8)	(1.6)
Cash Flow Hedging [Member]
Derivatives, Fair Value [Line Items]
Notional values of forward exchange contracts	$ 638.6