Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 2,033	$ 1,723	$ 1,870
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	(84)	(603)	376
Realized and unrealized gains (losses) on derivatives	25	7	(18)
Pension and postretirement plans	(1)	(3)	4
Other comprehensive income (loss)	(60)	(599)	362
Total comprehensive income	1,973	1,124	2,232
Comprehensive income attributable to noncontrolling interests:
Net income	184	191	233
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	(15)	(123)	19
Realized and unrealized gains on derivatives	(1)	1	1
Other comprehensive income (loss)	(16)	(122)	20
Comprehensive income attributable to noncontrolling interests	168	69	253
Comprehensive income attributable to Johnson Controls	$ 1,805	$ 1,055	$ 1,979