Goodwill and Other Intangible Assets - Changes in Carrying Amount of Goodwill (Details) $ in Millions	9 Months Ended
Jun. 30, 2020 USD ($)
Goodwill
Balance at beginning of period	$ 1,071.1
Acquisition of businesses	551.9
Translation	8.0
Balance at end of period	1,631.0
Architecture & Software
Goodwill
Balance at beginning of period	432.3
Acquisition of businesses	161.3
Translation	6.9
Balance at end of period	600.5
Control Products & Solutions
Goodwill
Balance at beginning of period	638.8
Acquisition of businesses	390.6
Translation	1.1
Balance at end of period	$ 1,030.5

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://fasb.org/us-gaap/role/ref/legacyRef
-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

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-SubTopic 20
-Section 50
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Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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

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