Fair Value Measurements (Schedule of Fair Value of Assets and Liabilities) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Sep. 30, 2013	Sep. 30, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Assets at Fair Value	$ 117.3	$ 125.9
Total Liabilities at Fair Value	62.4	41.3
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Assets at Fair Value	0	0
Total Liabilities at Fair Value	0	0
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Assets at Fair Value	117.3	125.9
Total Liabilities at Fair Value	62.4	41.3
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Assets at Fair Value	0	0
Total Liabilities at Fair Value	0	0
Interest rate management contract [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	49.3	35.4
Derivative liabilities	7.8	9.6
Interest rate management contract [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Interest rate management contract [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	49.3	35.4
Derivative liabilities	7.8	9.6
Interest rate management contract [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Interest rate management contract [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	49.3	35.4	49.7
Derivative liabilities	7.8	9.6	25.1
Forward Exchange Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	68.0	90.5
Derivative liabilities	54.6	31.7
Forward Exchange Contracts [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Forward Exchange Contracts [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	68.0	90.5
Derivative liabilities	54.6	31.7
Forward Exchange Contracts [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	0
Derivative liabilities	0	0
Forward Exchange Contracts [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	68.0	90.5	77.9
Derivative liabilities	$ 54.6	$ 31.7	$ 21.7