Income Taxes, - Summary of Positions for which Significant Change in Unrecognized Tax Benefits is Reasonably Possible (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Income Taxes [Abstract]
Beginning balance	$ 111.5	$ 116.4	$ 83.8
Increases related to prior year tax positions	1.7	2.2	7.7
Decreases related to prior year tax positions	(3.3)	(8.8)	(1.9)
Increases related to current year tax positions	3.2	4.9	36.5
Decreases related to current year tax positions	(1.3)	(3.2)	(1.1)
Reductions due to lapse of statute of limitations	(2.6)	0	(8.6)
Reductions for settlements with taxing authorities	0	0	0
Ending balance	$ 109.2	$ 111.5	$ 116.4