Face (par) amount of debt instrument at time of issuance.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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Balance Type:
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Name:	us-gaap_DebtInstrumentAxis=jci_A2.5billionfacilityexpiringDec2024Domain
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Name:	us-gaap_DebtInstrumentAxis=jci_A2billionfacilityterminatedDec2019Domain
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Name:	us-gaap_ShortTermDebtTypeAxis=jci_EuropeanfinancingarrangementsdueSept2020Member
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Debt and Financing Arrangements - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Apr. 30, 2020
$500 million due March 2020 [Member]
Debt Instrument [Line Items]
Repayments of Debt	$ 500
Debt Instrument, Interest Rate, Stated Percentage	5.00%
$2.5 billion facility expiring Dec 2024 [Domain]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 2,500
$500 million facility expiring Dec 2020 [Domain]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 500
$2 billion facility, terminated Dec 2019 [Domain]
Debt Instrument [Line Items]
Debt Instrument, Term		5 years
Line of Credit Facility, Maximum Borrowing Capacity		$ 2,000
Combined $750 million of facilities terminated Dec 2019 [Domain]
Debt Instrument [Line Items]
Debt Instrument, Term		364 days
Line of Credit Facility, Maximum Borrowing Capacity		$ 750
Revolving Credit Facility [Member] \| Floating rate term loan [Domain]
Debt Instrument [Line Items]
Debt Instrument, Term
Subsequent Event [Member] \| Bank term loans due April 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 575
Subsequent Event [Member] \| European financing arrangements due Sept 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 675