Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Operating Activities of Continuing Operations
Net income from continuing operations attributable to Johnson Controls	$ 1,513	$ 631	$ 1,100
Income from continuing operations attributable to noncontrolling interests	233	164	189
Net income from continuing operations	1,746	795	1,289
Adjustments to reconcile net income from continuing operations to cash provided by operating activities:
Depreciation and amortization	845	822	825
Pension and postretirement benefit expense (income)	(551)	118	515
Pension and postretirement contributions	(68)	(61)	(53)
Equity in earnings of partially-owned affiliates, net of dividends received	(117)	(36)	(34)
Deferred income taxes	36	(537)	612
Non-cash restructuring and impairment charges	98	582	235
Equity-based compensation	76	74	95
Other - net	(85)	(90)	29
Changes in assets and liabilities, excluding acquisitions and divestitures:
Accounts receivable	(143)	534	(312)
Inventories	(219)	45	(72)
Other assets	(164)	(52)	(99)
Restructuring reserves	(44)	(29)	(121)
Accounts payable and accrued liabilities	813	(717)	56
Accrued income taxes	328	1,031	(1,222)
Cash provided by operating activities from continuing operations	2,551	2,479	1,743
Investing Activities of Continuing Operations
Capital expenditures	(552)	(443)	(586)
Sale of property, plant and equipment	124	127	27
Acquisition of businesses, net of cash acquired	(725)	(77)	(25)
Business divestitures, net of cash divested	19	135	12
Changes in long-term investments	8	0	25
Proceeds for equity swap	35	0	14
Other - net	1	0	0
Cash used by investing activities from continuing operations	(1,090)	(258)	(533)
Financing Activities of Continuing Operations
Decrease in short-term debt - net	(17)	(33)	(1,296)
Increase in long-term debt	496	1,804	0
Repayment of long-term debt	(507)	(1,386)	(2,333)
Debt financing costs	(3)	(12)	0
Stock repurchases and retirements	(1,307)	(2,204)	(5,983)
Payment of cash dividends	(762)	(790)	(920)
Proceeds from the exercise of stock options	178	75	171
Dividends paid to noncontrolling interests	(142)	(114)	(132)
Cash received related to prior acquisitions and divestitures, net	1	2	4
Employee equity-based compensation withholding	(33)	(34)	(31)
Cash paid to acquire a noncontrolling interest	(14)	(132)	0
Other - net	(21)	0	1
Cash used by financing activities from continuing operations	(2,131)	(2,824)	(10,519)
Cash Used by Operating Activities, Discontinued Operations	(64)	(260)	(541)
Cash Provided by Investing Activities, Discontinued Operations	0	0	12,611
Cash Used by Financing Activities, Discontinued Operations	0	(113)	(35)
Cash Provided (Used) by Discontinued Operations	(64)	(373)	12,035
Effect of exchange rate changes on cash, cash equivalents and restricted cash	116	115	(120)
Change in cash, cash equivalents and restricted cash held for sale	0	0	15
Increase (decrease) in cash, cash equivalents and restricted cash	(618)	(861)	2,621
Cash, cash equivalents and restricted cash at beginning of period	1,960	2,821	200
Cash, cash equivalents and restricted cash at end of period	1,342	1,960	2,821
Less: Restricted cash	6	9	16
Cash and cash equivalents at end of period	$ 1,336	$ 1,951	$ 2,805