Financial Instruments (Schedule of Outstanding Currency Price Risk Management Instruments) (Details) (Forward Exchange Contracts [Member], USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Mar. 31, 2013	Sep. 30, 2012
Derivative [Line Items]
US$ Notional	$ 2,556.1	$ 2,605.7
Years Average Maturity	0 years 11 months	1 year 0 months
Cash Flow Hedges [Member]
Derivative [Line Items]
US$ Notional	1,379.5	1,348.8
Years Average Maturity	0 years 6 months	0 years 7 months
Net Investment Hedges [Member]
Derivative [Line Items]
US$ Notional	813.3	779.2
Years Average Maturity	1 year 11 months	2 years 6 months
Hedges Not Designated [Member]
Derivative [Line Items]
US$ Notional	$ 363.3	$ 477.7
Years Average Maturity	0 years 1 month	0 years 1 month