TIFSA Condensed Statement of Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Condensed Statement of Income Captions [Line Items]
Net income (loss)	$ 483	$ (115)	$ 754	$ 263
Foreign currency translation adjustments	204	252	283	(451)
Realized and unrealized gains (losses) on derivatives	(10)	(8)	(11)	(4)
Realized and unrealized gains (losses) on marketable securities	(2)	11	(2)	9
Other comprehensive income (loss)	192	255	270	(446)
Total comprehensive income (loss)	675	140	1,024	(183)
Comprehensive income attributable to noncontrolling interests	77	42	137	51
Comprehensive income (loss) attributable to Johnson Controls	598	98	887	(234)
Consolidation, Eliminations [Member]
Condensed Statement of Income Captions [Line Items]
Net income (loss)	(59)	672	(674)	1,685
Foreign currency translation adjustments	(334)	(241)	(358)	418
Realized and unrealized gains (losses) on derivatives	6	6	5	6
Realized and unrealized gains (losses) on marketable securities	2	(11)	2	(9)
Other comprehensive income (loss)	(326)	(246)	(351)	415
Total comprehensive income (loss)	(385)	426	(1,025)	2,100
Comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Johnson Controls	(385)	426	(1,025)	2,100
Parent Company [Member]
Condensed Statement of Income Captions [Line Items]
Net income (loss)	438	(148)	668	181
Foreign currency translation adjustments	168	241		(418)
Realized and unrealized gains (losses) on derivatives	(6)	(6)		(6)
Realized and unrealized gains (losses) on marketable securities	(2)	11		9
Other comprehensive income (loss)	160	246	219	(415)
Total comprehensive income (loss)	598	98	887	(234)
Comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Johnson Controls	598	98	887	(234)
Guarantor Subsidiaries [Member]
Condensed Statement of Income Captions [Line Items]
Net income (loss)	532	(114)	806	(400)
Foreign currency translation adjustments	(16)	(7)	(23)	(7)
Realized and unrealized gains (losses) on derivatives	0	0	0	0
Realized and unrealized gains (losses) on marketable securities	0	0	0	0
Other comprehensive income (loss)	(16)	(7)	(23)	(7)
Total comprehensive income (loss)	516	(121)	783	(407)
Comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Johnson Controls	516	(121)	783	(407)
Subsidiary Issuer [Member]
Condensed Statement of Income Captions [Line Items]
Net income (loss)	(18)	(358)	93	(1,404)
Foreign currency translation adjustments	(2)	(1)	(3)	26
Realized and unrealized gains (losses) on derivatives	0	0	0	0
Realized and unrealized gains (losses) on marketable securities	0	7	(4)	7
Other comprehensive income (loss)	(2)	6	(7)	33
Total comprehensive income (loss)	(20)	(352)	86	(1,371)
Comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Johnson Controls	(20)	(352)	86	(1,371)
Non-Guarantor Subsidiaries [Member]
Condensed Statement of Income Captions [Line Items]
Net income (loss)	(410)	(167)	(139)	201
Foreign currency translation adjustments	388	260	441	(470)
Realized and unrealized gains (losses) on derivatives	(10)	(8)	(11)	(4)
Realized and unrealized gains (losses) on marketable securities	(2)	4	2	2
Other comprehensive income (loss)	376	256	432	(472)
Total comprehensive income (loss)	(34)	89	293	(271)
Comprehensive income attributable to noncontrolling interests	77	42	137	51
Comprehensive income (loss) attributable to Johnson Controls	(111)	47	156	(322)
Parent
Condensed Statement of Income Captions [Line Items]
Realized and unrealized gains (losses) on derivatives	(6)	(6)		(6)
Realized and unrealized gains (losses) on marketable securities	(2)	11		9
Comprehensive income (loss) attributable to Johnson Controls	$ 598	$ 98	887	$ (234)
Parent \| Parent Company [Member]
Condensed Statement of Income Captions [Line Items]
Foreign currency translation adjustments			226
Realized and unrealized gains (losses) on derivatives			(5)
Realized and unrealized gains (losses) on marketable securities			$ (2)

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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