Contingencies, Significant Estimates and Concentrations (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Loss contingencies
Approximate percentage of workforce covered under collective bargaining agreements (as a percent)	26.00%
Significant portion of revenue from DoD
DoD	$ 1,205.0	$ 922.1	$ 1,603.7
Foreign military sales	1.8	0.3	28.0
Total DoD sales	$ 1,206.8	$ 922.4	$ 1,631.7
Percentage of maximum sales not accounted for by single customer (as a percent)	10.00%	10.00%	10.00%
Personal Injury Actions and Other
Loss contingencies
Reserve for loss contingencies	$ 38.3	$ 40.4
Maximum self-insurance available per claim	5.0
Performance and specialty bonds
Loss contingencies
Commitments and contingencies	503.6
Standby letters of credit
Loss contingencies
Commitments and contingencies	$ 110.8
Defense
Loss contingencies
Former Gain Contingency, Recognized in Current Period			$ 4.6
Reduction of Revenue - Contractual Obligations			$ 8.9

Represents the maximum self-insurance for future claims per claim held by the entity.

No definition available.

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- Definition

Represents the percentage of maximum sales not accounted for by a single customer.

+ References

No definition available.

+ Details

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- Definition

Reduction of Revenue - Contractual Obligations

+ References

No definition available.

+ Details

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- Definition

Revenue from sale of goods and services rendered during the reporting period from Department of Defense, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

No definition available.

+ Details

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- Definition

-- None. No documentation exists for this element. --

+ References

No definition available.

+ Details

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- Definition

Revenue from sale of goods and services rendered during the reporting period from Department of Defense of the domestic country in which the entity operates, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

No definition available.

+ Details

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- Definition

Revenue from sale of goods and services rendered during the reporting period from Department of Defense of the foreign country, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

No definition available.

+ Details

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- Definition

The percentage of employees covered by a collective bargaining agreement as of the balance sheet date, when it serves as a benchmark in a concentration of risk calculation.

+ References

No definition available.

+ Details

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- Definition

Amount of gain recognized in the period that had been disclosed in prior periods as a contingent gain.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 30
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6397426&loc=d3e17499-108355

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Amount of loss contingency liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

+ Details

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- Definition

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

+ 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

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349

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