TYCO INTERNATIONAL FINANCE S.A. Condensed Statement of Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Condensed Statement of Income Captions [Line Items]
Net income (loss)	$ 1,819	$ (652)	$ 1,679
Foreign currency translation adjustments	103	(94)	(825)
Realized and unrealized gains (losses) on derivatives	(14)	9	(10)
Realized and unrealized gains (losses) on marketable securities	5	(1)	0
Pension and postretirement plans	0	(1)	(10)
Other comprehensive income (loss)	94	(87)	(845)
Total comprehensive income (loss)	1,913	(739)	834
Comprehensive income attributable to noncontrolling interests	203	225	91
Comprehensive income (loss) attributable to Johnson Controls	1,710	(964)	$ 743
Consolidation, Eliminations [Member]
Condensed Statement of Income Captions [Line Items]
Net income (loss)	(1,743)	2,762
Foreign currency translation adjustments	(108)	105
Realized and unrealized gains (losses) on derivatives	14	(11)
Realized and unrealized gains (losses) on marketable securities	(5)	1
Pension and postretirement plans		1
Other comprehensive income (loss)	(99)	96
Total comprehensive income (loss)	(1,842)	2,858
Comprehensive income attributable to noncontrolling interests	0	0
Comprehensive income (loss) attributable to Johnson Controls	(1,842)	2,858
Johnson Controls International plc
Condensed Statement of Income Captions [Line Items]
Net income (loss)	1,611	(868)
Foreign currency translation adjustments	108	(105)
Realized and unrealized gains (losses) on derivatives	(14)	11
Realized and unrealized gains (losses) on marketable securities	5	(1)
Pension and postretirement plans		(1)
Other comprehensive income (loss)	99	(96)
Total comprehensive income (loss)	1,710	(964)
Comprehensive income attributable to noncontrolling interests	0	0
Comprehensive income (loss) attributable to Johnson Controls	1,710	(964)
Tyco Fire & Security Finance SCA
Condensed Statement of Income Captions [Line Items]
Net income (loss)	1,118	(1,529)
Foreign currency translation adjustments	(54)	0
Realized and unrealized gains (losses) on derivatives	0	0
Realized and unrealized gains (losses) on marketable securities	0	0
Pension and postretirement plans		0
Other comprehensive income (loss)	(54)	0
Total comprehensive income (loss)	1,064	(1,529)
Comprehensive income attributable to noncontrolling interests	0	0
Comprehensive income (loss) attributable to Johnson Controls	1,064	(1,529)
Tyco International Finance S.A.
Condensed Statement of Income Captions [Line Items]
Net income (loss)	(978)	(341)
Foreign currency translation adjustments	20	0
Realized and unrealized gains (losses) on derivatives	0	0
Realized and unrealized gains (losses) on marketable securities	(4)	0
Pension and postretirement plans		0
Other comprehensive income (loss)	16	0
Total comprehensive income (loss)	(962)	(341)
Comprehensive income attributable to noncontrolling interests	0	0
Comprehensive income (loss) attributable to Johnson Controls	(962)	(341)
Other Subsidiaries
Condensed Statement of Income Captions [Line Items]
Net income (loss)	1,811	(676)
Foreign currency translation adjustments	137	(94)
Realized and unrealized gains (losses) on derivatives	(14)	9
Realized and unrealized gains (losses) on marketable securities	9	(1)
Pension and postretirement plans		(1)
Other comprehensive income (loss)	132	(87)
Total comprehensive income (loss)	1,943	(763)
Comprehensive income attributable to noncontrolling interests	203	225
Comprehensive income (loss) attributable to Johnson Controls	$ 1,740	$ (988)