Goodwill and Intangible Assets - Goodwill RollForward (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2017	Sep. 30, 2016
GoodwillRollForward
Goodwill, Beginning Balance	$ 39,936	$ 17,249
Acquisitions	7,121	23,264
Divestitures	51	577
Goodwill Purchase Accounting Adjustments	(313)
Goodwill, Ending Balance	46,693	39,936
Commercial & Industrial [Member]
GoodwillRollForward
Goodwill, Beginning Balance	3,806	0
Acquisitions	3,411	3,806
Divestitures	0
Goodwill Purchase Accounting Adjustments	(41)
Goodwill, Ending Balance	7,176	3,806
Infrastructure Solutions [Member]
GoodwillRollForward
Goodwill, Beginning Balance	27,499	8,618
Acquisitions	3,710	19,458
Divestitures	51	577
Goodwill Purchase Accounting Adjustments	(272)
Goodwill, Ending Balance	30,886	27,499
Residential [Member]
GoodwillRollForward
Goodwill, Beginning Balance	8,631	8,631
Acquisitions	0	0
Divestitures	0
Goodwill Purchase Accounting Adjustments	0
Goodwill, Ending Balance	$ 8,631	$ 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=64834752&loc=SL49117168-202975

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- Definition

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.

+ References

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- Definition

Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ 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=73531572&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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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

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

+ References

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