Fair Value Measurements (Schedule of the Carrying Values and Fair Values of Financial Instruments) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Sep. 30, 2012
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including current portion	$ 4,741.4	$ 4,658.5
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, including current portion	5,045.7	5,005.9
Interest rate management contract [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	42.6	49.7
Derivative liabilities	10.4	25.1
Interest rate management contract [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	42.6	49.7
Derivative liabilities	10.4	25.1
Interest rate management contract [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	42.6	49.7
Derivative liabilities	10.4	25.1
Forward Exchange Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	93.7	77.9
Derivative liabilities	22.5	21.7
Forward Exchange Contracts [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	93.7	77.9
Derivative liabilities	22.5	21.7
Forward Exchange Contracts [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	93.7	77.9
Derivative liabilities	$ 22.5	$ 21.7