Goodwill and Intangible Assets - Goodwill RollForward (Details) $ in Thousands	9 Months Ended
Jun. 30, 2018 USD ($)
Goodwill [Line Items]
Goodwill, Beginning Balance	$ 46,693
Acquisitions	2,561
Divestitures	0
Goodwill Purchase Accounting Adjustments	45
Goodwill, Ending Balance	49,299
Commercial & Industrial [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	7,176
Acquisitions	0
Divestitures	0
Goodwill Purchase Accounting Adjustments	0
Goodwill, Ending Balance	7,176
Communications [Member]
Goodwill [Line Items]
Acquisitions	2,561
Goodwill, Ending Balance	2,561
Infrastructure Solutions [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	30,886
Acquisitions	0
Divestitures	0
Goodwill Purchase Accounting Adjustments	45
Goodwill, Ending Balance	30,931
Residential [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	8,631
Acquisitions	0
Divestitures	0
Goodwill Purchase Accounting Adjustments	0
Goodwill, Ending Balance	$ 8,631

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=84229725&loc=d3e961-128460

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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