Restructuring and Related Costs - Schedule of Restructuring Reserve by Type of Cost (Details) - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2024	Dec. 31, 2023
Restructuring Reserve [Roll Forward]
Restructuring and related costs	$ 33	$ 35
Current Restructuring Plans
Restructuring Reserve [Roll Forward]
Restructuring and related costs	33
Utilized—cash	(4)
Utilized—noncash	(8)
Restructuring reserve, ending balance	21
Previous Restructuring Plans
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	75
Utilized—cash	(27)
Other	1
Restructuring reserve, ending balance	49
Employee Severance and Termination Benefits \| Current Restructuring Plans
Restructuring Reserve [Roll Forward]
Restructuring and related costs	25
Utilized—cash	(4)
Utilized—noncash	0
Restructuring reserve, ending balance	21
Employee Severance and Termination Benefits \| Previous Restructuring Plans
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	58
Utilized—cash	(27)
Other	0
Restructuring reserve, ending balance	31
Long-Lived Asset Impairments \| Current Restructuring Plans
Restructuring Reserve [Roll Forward]
Restructuring and related costs	8
Utilized—cash	0
Utilized—noncash	(8)
Restructuring reserve, ending balance	0
Other \| Previous Restructuring Plans
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	17
Utilized—cash	0
Other	1
Restructuring reserve, ending balance	$ 18

Restructuring Costs, Other

No definition available.

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Namespace Prefix:	jci_
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- Definition

Amount of cash payments made as the result of exit or disposal activities. Excludes payments associated with a discontinued operation or an asset retirement obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 420
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482017/420-10-50-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 17
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-17

+ Details

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- Definition

Amount, after cash payment, of expenses associated with exit or disposal activities pursuant to an authorized plan and expenses resulting from the write-down of assets. Excludes expenses related to a business combination, a discontinued operation or an asset retirement obligation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (b)
-SubTopic 10
-Topic 230
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-28

+ Details

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- Definition

Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 420
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 5.P.4.b.2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479823/420-10-S99-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 420
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482017/420-10-50-1

+ Details

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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.

+ Details

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- Definition

Amount of decrease in the reserve for full or partial settlement through consideration other than cash.

+ References

+ Details

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- Details

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- Details

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