Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Tax Contingency [Line Items]
Effective income tax rate	8.00%	9.00%	10.00%	16.00%
Statutory income tax rate			35.00%
Unrecognized tax benefits	$ 15.2		$ 15.2
Unrecognized tax benefits that would impact the effective tax rate	15.2		15.2
Other long-term liabilities
Income Tax Contingency [Line Items]
Estimated accrued interest and penalties	$ 3.5		$ 3.5