Income Taxes - Narrative (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Income Tax Contingency [Line Items]
Effective income tax rate	9.00%	25.00%	11.00%	18.00%
Statutory income tax rate			35.00%
Unrecognized tax benefits	$ 14.8us-gaap_UnrecognizedTaxBenefits		$ 14.8us-gaap_UnrecognizedTaxBenefits
Unrecognized tax benefits that would impact the effective tax rate	14.8		14.8
Other long-term liabilities
Income Tax Contingency [Line Items]
Estimated accrued interest and penalties	$ 3.5		$ 3.5

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

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-Glossary Unrecognized Tax Benefit

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Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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