Business Acquisitions, Goodwill and Intangible Assets (Details 3) (USD $)	6 Months Ended
Mar. 31, 2013	Mar. 31, 2012	Sep. 30, 2012
Identifiable intangible assets with finite useful lives
Gross Amount	$ 250,400,000		$ 242,500,000
Accumulated Amortization	(156,300,000)		(145,500,000)
Intangible Assets, Net	94,112,000		96,973,000
Amortization expense	10,800,000	11,800,000
Estimated amortization expense of intangible assets for the remainder of fiscal 2013 and for the succeeding years
2013 (six months remaining)	10,400,000
2014	18,900,000
2015	15,900,000
2016	13,200,000
2017	11,900,000
Thereafter	23,800,000
Intangible Assets, Net	94,112,000		96,973,000
Backlog
Identifiable intangible assets with finite useful lives
Gross Amount	95,200,000		91,100,000
Accumulated Amortization	(86,900,000)		(83,800,000)
Intangible Assets, Net	8,300,000		7,300,000
Estimated amortization expense of intangible assets for the remainder of fiscal 2013 and for the succeeding years
Intangible Assets, Net	8,300,000		7,300,000
Backlog \| Minimum
Identifiable intangible assets with finite useful lives
Amortization Period	1 year
Backlog \| Maximum
Identifiable intangible assets with finite useful lives
Amortization Period	5 years
Customer relationships
Identifiable intangible assets with finite useful lives
Gross Amount	147,400,000		143,600,000
Accumulated Amortization	(61,700,000)		(54,100,000)
Intangible Assets, Net	85,700,000		89,500,000
Amortization Period	10 years
Estimated amortization expense of intangible assets for the remainder of fiscal 2013 and for the succeeding years
Intangible Assets, Net	85,700,000		89,500,000
Trademark / tradename
Identifiable intangible assets with finite useful lives
Gross Amount	7,800,000		7,800,000
Accumulated Amortization	(7,700,000)		(7,600,000)
Intangible Assets, Net	100,000		200,000
Amortization Period	2 years
Estimated amortization expense of intangible assets for the remainder of fiscal 2013 and for the succeeding years
Intangible Assets, Net	$ 100,000		$ 200,000

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

-Subparagraph a(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 45

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-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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

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-Name Accounting Standards Codification

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Amount of amortization expense expected to be recognized after the fifth fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of amortization expense expected to be recognized during the fourth fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of amortization expense expected to be recognized during the third fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of amortization expense expected to be recognized during the second fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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