Contingencies - Litigation and Other Matters (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
Mar. 31, 2015	Sep. 30, 2014
Loss Contingencies [Line Items]
Company's liability under Deferred Prosecution Agreement (percent)	4.00%
Maximum liability under the DPA and other settlement agreements	$ 48.0
Portion of liability under DPA that has been paid as of balance sheet date	24.9us-gaap_LossContingencyDamagesPaidValue
Additional liability recorded as of end of period	0.8
Accrued amounts for litigation and other contingent liabilities	8.4	13.4
Performance Bonds
Loss Contingencies [Line Items]
Letters of credit secured using cash collateral	42.6
Pledged Assets Separately Reported, Securities Pledged for Other Debt Obligations, at Fair Value	$ 217.4

Company's Liability Under Deferred Prosecution Agreement, Percentage of Company's Adjusted EBITDA

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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- Details

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- Definition

Amount of loss contingency liability.

+ References

+ Details

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- Definition

Amount of loss contingency liability expected to be resolved within one year or the normal operating cycle, if longer.

+ References

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- Definition

Amount of damages paid to the plaintiff in the legal matter.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

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-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (a)

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-Paragraph 9

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- Definition

The estimated maximum amount of possible loss from the contingency.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

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- Definition

The fair value, as of the date of each statement of financial position presented, of securities that are restricted as collateral for the payment of other debt obligations, and that are reclassified and separately reported in the statement of financial position because the transferee has the right by contract or custom to sell or re-pledge them.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6467456&loc=d3e113888-111728

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