Credit Facilities and Indebtedness (Details) - Convertible Debt (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Contractual interest expense	$ 123.4	$ 122.2	$ 130.8
Remaining discount amortization period (years)	7 months
Convertible Debentures [Member]
Contractual interest expense	27.5	27.5	27.5
Discount amortization	$ 36.7	$ 33.4	$ 30.6