Goodwill and Intangible Assets - Schedule of Changes in Goodwill (Details) $ in Thousands	9 Months Ended
Jun. 30, 2017 USD ($)
Goodwill [Roll Forward]
Balance as of September 30, 2016	$ 273,660
Impact of segment change	0
Goodwill acquired through acquisitions	14,936
Acquisition adjustments	(6)
Balance as of June 30, 2017	288,590
Operating Segments \| I/DD
Goodwill [Roll Forward]
Balance as of September 30, 2016	104,155
Impact of segment change	35,212
Goodwill acquired through acquisitions	626
Acquisition adjustments	0
Balance as of June 30, 2017	139,993
Operating Segments \| SRS
Goodwill [Roll Forward]
Balance as of September 30, 2016	81,909
Impact of segment change	0
Goodwill acquired through acquisitions	461
Acquisition adjustments	0
Balance as of June 30, 2017	82,370
Operating Segments \| ARY
Goodwill [Roll Forward]
Balance as of September 30, 2016	73,464
Impact of segment change	(35,212)
Goodwill acquired through acquisitions	0
Acquisition adjustments	0
Balance as of June 30, 2017	38,252
Corporate and Other
Goodwill [Roll Forward]
Balance as of September 30, 2016	14,132
Impact of segment change	0
Goodwill acquired through acquisitions	13,849
Acquisition adjustments	(6)
Balance as of June 30, 2017	$ 27,975

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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+ 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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Amount of transfers into (out 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.

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