Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Net sales	$ 5,594	$ 5,444	$ 10,935	$ 11,020
Cost of sales	3,651	3,643	7,264	7,416
Gross profit	1,943	1,801	3,671	3,604
Selling, general and administrative expenses	(1,253)	(1,451)	(2,547)	(2,878)
Restructuring and impairment costs	(96)	(62)	(96)	(173)
Net financing charges	(44)	(59)	(103)	(111)
Equity income	56	20	114	63
Income from continuing operations before income taxes	606	249	1,039	505
Income tax provision	209	13	270	78
Income from continuing operations	397	236	769	427
Income from discontinued operations, net of tax (Note 4)	0	0	124	0
Net income	397	236	893	427
Income from continuing operations attributable to noncontrolling interests	54	23	99	55
Net income attributable to Johnson Controls	343	213	794	372
Amounts attributable to Johnson Controls ordinary shareholders
Income from continuing operations	343	213	670	372
Income from discontinued operations	$ 0	$ 0	$ 124	$ 0
Earnings per share
Basic earnings per share from continuing operations	$ 0.48	$ 0.28	$ 0.93	$ 0.49
Basic earnings per share from discontinued operations	0	0	0.17	0
Basic earnings per share	0.48	0.28	1.10	0.49
Diluted earnings per share from continuing operations	0.48	0.28	0.93	0.49
Diluted earnings per share from discontinued operations	0	0	0.17	0
Diluted earnings per share	$ 0.48	$ 0.28	$ 1.10	$ 0.49
Products and Systems [Member]
Net sales	$ 4,032	$ 3,922	$ 7,831	$ 7,958
Cost of sales	2,751	2,741	5,470	5,607
Services [Member]
Net sales	1,562	1,522	3,104	3,062
Cost of sales	$ 900	$ 902	$ 1,794	$ 1,809