Goodwill and Other Intangible Assets Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Jun. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Goodwill [Roll Forward]
Goodwill, Beginning Balance		$ 21,024	$ 4,460
Business Acquisitions		(256)	16,622
Business Divestitures		(1,269)	(19)
Currency Translation and Other		189	(39)
Goodwill, Ending Balance		19,688	21,024	$ 4,460
Power Solutions
Goodwill [Roll Forward]
Goodwill, Beginning Balance		1,086	1,082
Business Acquisitions		0	0
Business Divestitures		0	0
Currency Translation and Other		11	4
Goodwill, Ending Balance		1,097	1,086	1,082
Building Solutions North America
Goodwill [Roll Forward]
Business Divestitures	$ (3)
Building Solutions North America \| Building Technologies & Solutions
Goodwill [Roll Forward]
Goodwill, Beginning Balance		9,734	930
Business Acquisitions		(147)	8,829
Business Divestitures		0	(3)
Currency Translation and Other		50	(22)
Goodwill, Ending Balance		9,637	9,734	930
Building Solutions EMEA/LA \| Building Technologies & Solutions
Goodwill [Roll Forward]
Goodwill, Beginning Balance		1,981	195
Business Acquisitions		(37)	1,787
Business Divestitures		0	0
Impairments				(47)
Currency Translation and Other		68	(1)
Goodwill, Ending Balance		2,012	1,981	195
Building Solutions Asia Pacific \| Building Technologies & Solutions
Goodwill [Roll Forward]
Goodwill, Beginning Balance		1,260	310
Business Acquisitions		(14)	968
Business Divestitures		2	0
Currency Translation and Other		11	(18)
Goodwill, Ending Balance		1,255	1,260	310
Global Products \| Building Technologies & Solutions
Goodwill [Roll Forward]
Goodwill, Beginning Balance		6,963	1,943
Business Acquisitions		(58)	5,038
Business Divestitures		(1,267)	16
Currency Translation and Other		49	(2)
Goodwill, Ending Balance		$ 5,687	$ 6,963	$ 1,943

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
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