Income Taxes - Narrative (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Income Tax Contingency [Line Items]
Effective income tax rate	25.00%	12.00%	18.00%	13.00%
Statutory income tax rate			35.00%
Unrecognized tax benefits	$ 13.9		$ 13.9
Unrecognized tax benefits that would impact the effective tax rate	13.9		13.9
Other long-term liabilities
Income Tax Contingency [Line Items]
Estimated accrued interest and penalties	$ 4.0		$ 4.0