Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 558	$ 483	$ 957	$ 754
Other comprehensive income (loss), net of tax
Foreign currency translation adjustments	117	204	(1)	283
Realized and unrealized gains (losses) on derivatives	17	(10)	19	(11)
Realized and unrealized losses on marketable securities	0	(2)	0	(2)
Other comprehensive income	134	192	18	270
Total comprehensive income	692	675	975	1,024
Comprehensive income attributable to noncontrolling interests	49	77	103	137
Comprehensive income attributable to Johnson Controls	$ 643	$ 598	$ 872	$ 887