Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

+ Details

Name:	invest_DerivativeNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Gains (losses) reclassified from CTA to income for the Company's outstanding net investment hedges

+ References

No definition available.

+ Details

Name:	jci_GainsLossesReclassifiedFromCtaToIncomeForCompanysOutstandingNetInvestmentHedges
Namespace Prefix:	jci_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

+ Details

Name:	us-gaap_DerivativeInstrumentsGainLossRecognizedInOtherComprehensiveIncomeEffectivePortionNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=jci_ForeignCurrencyDenominatedDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtSecurityAxis=jci_A58millioneuronetinvestmenthedgeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtSecurityAxis=jci_A215millionEURmaturinginMarch2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtSecurityAxis=jci_OnebillioneuronetinvestmenthedgeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtSecurityAxis=jci_A750millioneuronetinvestmenthedgeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtSecurityAxis=jci_A423millioneuronetinvestmenthedgeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_NetInvestmentHedgingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Derivative Instruments and Hedging Activities - Additional Information (Detail) € in Millions, ¥ in Billions	3 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2018 EUR (€)	Dec. 31, 2018 JPY (¥)	Sep. 30, 2018 EUR (€)	Sep. 30, 2018 JPY (¥)
Derivative [Line Items]
Gains (losses) reclassified from CTA to income for the Company's outstanding net investment hedges \| $	$ 0	$ 0
Foreign Currency Denominated Debt [Member]
Derivative [Line Items]
Notional amount \| ¥				¥ 35		¥ 35
58 million euro net investment hedge [Member] \| Foreign Currency Denominated Debt [Member]
Derivative [Line Items]
Notional amount			€ 58		€ 58
215 million EUR maturing in March 2020 [Member] \| Foreign Currency Denominated Debt [Member]
Derivative [Line Items]
Notional amount			215		215
One billion euro net investment hedge [Member] \| Foreign Currency Denominated Debt [Member]
Derivative [Line Items]
Notional amount			1,000		1,000
750 million euro net investment hedge [Member] \| Foreign Currency Denominated Debt [Member]
Derivative [Line Items]
Notional amount			750		750
423 million euro net investment hedge [Member] \| Foreign Currency Denominated Debt [Member]
Derivative [Line Items]
Notional amount			€ 423		€ 423
Net Investment Hedging [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net \| $	$ 34,000,000	$ (36,000,000)