Consolidated Statements of Shareholders' Equity Attributable to Johnson Controls Ordinary Shareholders Consolidated Statements of Shareholders' Equity Attributable to Johnson Controls Ordinary Shareholders - USD ($) $ in Millions		Total	Ordinary Shares	Capital in excess of par value	Retained Earnings	Treasury Stock, at Cost	Accumulated Other Comprehensive Loss
Beginning balance at Sep. 30, 2018		$ 21,164	$ 10	$ 16,549	$ 6,604	$ (1,053)	$ (946)
Comprehensive income (loss)		229	0	0	355	0	(126)
Cash dividends - ordinary shares		(240)	0	0	(240)	0	0
Treasury Stock, Value, Acquired, Cost Method		(467)	0	0	0	(467)	0
Accounting Pronouncement | Adoption of ASC 606		(45)	0	0	(45)	0	0
Accounting Pronouncement | Adoption of ASU 2016-01		0	0	0	8	0	(8)
Accounting Pronouncement | Adoption of ASU 2016-16		(546)	0	0	(546)	0	0
Other, including options exercised		7	0	30	0	(23)	0
Ending balance at Dec. 31, 2018		20,102	10	16,579	6,136	(1,543)	(1,080)
Beginning balance at Sep. 30, 2019		19,766	8	16,812	4,827	(1,086)	(795)
Comprehensive income (loss)		414	0	0	159	0	255
Cash dividends - ordinary shares		(201)	0	0	(201)	0	0
Stock Repurchased and Retired During Period, Value		(651)	0	0	(651)	0	0
Accounting Pronouncement | Adoption of ASU 2016-01	[1]	0
Accounting Pronouncement | Adoption of ASC 842		(5)	0	0	(5)	0	0
Other, including options exercised		6	0	36	0	(30)	0
Ending balance at Dec. 31, 2019		$ 19,329	$ 8	$ 16,848	$ 4,129	$ (1,116)	$ (540)

[1] ** During the quarter ended December 31, 2018, the Company adopted ASU 2016-01, "Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities." As a result, the Company reclassified $8 million of unrealized gains on marketable securities to retained earnings as of October 1, 2018.