Credit Facilities and Indebtedness (Details) - Outstanding Debt (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Credit facilities	$ 0	$ 140.0
Total principal debt obligations	2,150.0	1,790.0
Swap fair value adjustments:
Total outstanding debt, net	2,192.9	1,846.4
Convertible Notes [Member]
3.25% Convertible Notes	850.0	850.0
Discounts:
Discounts	(23.3)	(60.0)
7.5% Bonds [Member]
Bonds	500.0	500.0
Discounts:
Discounts	(1.8)	(2.1)
Swap fair value adjustments:
Swap fair value adjustments	48.4	77.0
5.5% Bonds [Member]
Bonds	300.0	300.0
Discounts:
Discounts	(0.9)	(1.0)
Swap fair value adjustments:
Swap fair value adjustments	22.6	42.5
5.35% Bonds [Member]
Bonds	500.0	0
Discounts:
Discounts	$ (2.1)	$ 0