Significant Restructuring Costs Change in Restructuring Reserve - 2018 Restructuring Plan (Details) - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	$ 158	$ 78
2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	158
Restructuring Reserve, Settled without Cash	(30)
Restructuring Reserve	128
Employee Severance \| 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	125
Restructuring Reserve, Settled without Cash	0
Restructuring Reserve	125
Fixed Asset Impairment \| 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	30
Restructuring Reserve, Settled without Cash	(30)
Restructuring Reserve	0
Other Restructuring \| 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	3
Restructuring Reserve, Settled without Cash	0
Restructuring Reserve	3
Global Products \| 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	76
Building Solutions EMEA/LA \| 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	32
Corporate Segment \| 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	24
Building Solutions Asia Pacific \| 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	14
Building Solutions North America \| 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	8
Power Solutions \| 2018 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment costs	$ 4

Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 5.P.3)
-URI http://asc.fasb.org/extlink&oid=27011515&loc=d3e140864-122747

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section 50
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.P.4(b))
-URI http://asc.fasb.org/extlink&oid=27011515&loc=d3e140904-122747

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
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-Section 50
-Paragraph 1
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.P.4(b)(2))
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
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-Section 50
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