Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Shareholders' Equity Attributable to Johnson Controls	Ordinary Shares	Ordinary Shares Held in Treasury, at Cost	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Shareholders' Equity Attributable to Noncontrolling Interests
Beginning Balance at Sep. 30, 2022		$ 16,268	$ 7	$ (1,203)	$ 17,224	$ 1,151	$ (911)	$ 1,134
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee equity-based compensation withholding taxes				(30)
Share-based compensation expense					19
Other, including options exercised					19
Net income attributable to Johnson Controls	$ 156					118
Cash dividends declared						(241)
Repurchases and retirements of ordinary shares	(154)					(154)
Other comprehensive income	228						47	63
Ending Balance at Dec. 31, 2022	17,243	16,046	$ 7	(1,233)	17,262	874	(864)	1,197
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash Dividends Declared per Ordinary Share (in dollars per share)			$ 0.35
Beginning Balance at Sep. 30, 2023	17,694	16,545	$ 7	(1,240)	17,349	1,384	(955)	1,149
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee equity-based compensation withholding taxes				(23)
Share-based compensation expense					20
Other, including options exercised					12
Net income attributable to Johnson Controls	404
Cash dividends declared						(252)
Repurchases and retirements of ordinary shares	0					0
Other comprehensive income	423						22
Ending Balance at Dec. 31, 2023	$ 17,874	$ 16,698	$ 7	$ (1,263)	$ 17,381	$ 1,506	$ (933)	$ 1,176
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash Dividends Declared per Ordinary Share (in dollars per share)			$ 0.37