TYCO INTERNATIONAL FINANCE S.A. Condensed Statement of Cash Flow (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Condensed Cash Flow Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	$ 12	$ 1,895	$ 1,600
Capital expenditures	(1,343)	(1,249)	(1,135)
Sale of property, plant and equipment	33	32	37
Acquisition of business, net of cash acquired	(6)	353	(22)
Business divestitures, net of cash divested	220	32	1,646
Changes in long-term investments	(41)	(48)	(44)
Net change in intercompany loans	0	0
Intercompany investment in subsidiaries	0
Other		(7)	(12)
Net cash used in investing activities	(1,137)	(887)	470
Increase (decrease) in short-term debt - net	145	556	(68)
Increase in long-term debt	1,865	1,501	299
Repayments of Long-term Debt	(1,297)	(1,299)	(191)
Debt financing costs	(18)	(45)	0
Payments for Repurchase of Common Stock	(651)	(501)	(1,362)
Payments of Dividends	(702)	(915)	(657)
Proceeds from the exercise of stock options	157	70	275
Net intercompany loan borrowings (repayments)	0	0
Equity from parent	0
Change in noncontrolling interest share	8
Change in noncontrolling Interest share		(2)	(38)
Dividends paid to noncontrolling interest	(88)	(306)	(68)
Dividend from Adient spin-off	2,050	0	0
Cash transferred to Adient related to spin-off	(665)	0	0
Payments for (Proceeds from) Previous Acquisition	(75)	0	0
Other	(12)	8	(11)
Net cash provided by financing activities	717	(933)	(1,821)
Effect of exchange rate changes on cash and cash equivalents	54	12	(81)
Cash And Cash Equivalents Held For Sale	96	(61)	(21)
Increase (decrease) in cash and cash equivalents	(258)	26	189
Cash and cash equivalents	321	579	553	$ 364
Consolidation, Eliminations [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	0	0
Capital expenditures	0	0
Sale of property, plant and equipment	0	0
Acquisition of business, net of cash acquired	0	0
Business divestitures	0	0
Changes in long-term investments	0	0
Net change in intercompany loans	940	(10)
Intercompany investment in subsidiaries	(3,814)
Other		0
Net cash used in investing activities	4,754	(10)
Increase (decrease) in short-term debt - net	(886)	0
Increase in long-term debt	0	0
Repayments of Long-term Debt	0	0
Debt financing costs	0	0
Payments for Repurchase of Common Stock	0	0
Payments of Dividends	0	0
Proceeds from the exercise of stock options	0	0
Net intercompany loan borrowings (repayments)	(940)	10
Equity from parent	(3,814)
Payments to Acquire Additional Interest in Subsidiaries		0
Change in noncontrolling interest share	0
Dividends paid to noncontrolling interest	0	0
Dividend from Adient spin-off	0
Cash transferred to Adient related to spin-off	0
Payments for (Proceeds from) Previous Acquisition	0
Other	0	0
Net cash provided by financing activities	(5,640)	10
Effect of exchange rate changes on cash and cash equivalents	0	0
Cash And Cash Equivalents Held For Sale	0	0
Increase (decrease) in cash and cash equivalents	(886)	0
Cash and cash equivalents	(886)	0	0
Other Subsidiaries
Condensed Cash Flow Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	(183)	1,245
Capital expenditures	(1,343)	(1,249)
Sale of property, plant and equipment	33	32
Acquisition of business, net of cash acquired	0	353
Business divestitures	220	32
Changes in long-term investments	(30)	(105)
Net change in intercompany loans	(640)	0
Intercompany investment in subsidiaries	0
Other		(7)
Net cash used in investing activities	(1,760)	(944)
Increase (decrease) in short-term debt - net	(445)	1,018
Increase in long-term debt	9	1,501
Repayments of Long-term Debt	(1,094)	(1,299)
Debt financing costs	(1)	(45)
Payments for Repurchase of Common Stock	0	(501)
Payments of Dividends	0	(915)
Proceeds from the exercise of stock options	0	67
Net intercompany loan borrowings (repayments)	300	(10)
Equity from parent	2,097
Payments to Acquire Additional Interest in Subsidiaries		(2)
Change in noncontrolling interest share	8
Dividends paid to noncontrolling interest	(88)	(306)
Dividend from Adient spin-off	2,050
Cash transferred to Adient related to spin-off	(578)
Payments for (Proceeds from) Previous Acquisition	(75)
Other	4	11
Net cash provided by financing activities	2,187	(481)
Effect of exchange rate changes on cash and cash equivalents	54	12
Cash And Cash Equivalents Held For Sale	96	(61)
Increase (decrease) in cash and cash equivalents	394	(229)
Cash and cash equivalents	718	324	553
Johnson Controls International plc
Condensed Cash Flow Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	(129)	11
Capital expenditures	0	0
Sale of property, plant and equipment	0	0
Acquisition of business, net of cash acquired	0	0
Business divestitures	0	0
Changes in long-term investments	0	0
Net change in intercompany loans	(300)	0
Intercompany investment in subsidiaries	1,998
Other		0
Net cash used in investing activities	(2,298)	0
Increase (decrease) in short-term debt - net	1,476	0
Increase in long-term debt	1,856	0
Repayments of Long-term Debt	(183)	0
Debt financing costs	(17)	0
Payments for Repurchase of Common Stock	(651)	0
Payments of Dividends	(702)	0
Proceeds from the exercise of stock options	157	3
Net intercompany loan borrowings (repayments)	583	0
Equity from parent	0
Payments to Acquire Additional Interest in Subsidiaries		0
Change in noncontrolling interest share	0
Dividends paid to noncontrolling interest	0	0
Dividend from Adient spin-off	0
Cash transferred to Adient related to spin-off	(87)
Payments for (Proceeds from) Previous Acquisition	0
Other	(16)	(3)
Net cash provided by financing activities	2,416	0
Effect of exchange rate changes on cash and cash equivalents	0	0
Cash And Cash Equivalents Held For Sale	0	0
Increase (decrease) in cash and cash equivalents	(11)	11
Cash and cash equivalents	0	11	0
Tyco Fire & Security Finance SCA
Condensed Cash Flow Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	182	0
Capital expenditures	0	0
Sale of property, plant and equipment	0	0
Acquisition of business, net of cash acquired	0	0
Business divestitures	0	0
Changes in long-term investments	0	0
Net change in intercompany loans	0	0
Intercompany investment in subsidiaries	1,716
Other		0
Net cash used in investing activities	(1,716)	0
Increase (decrease) in short-term debt - net	0	0
Increase in long-term debt	0	0
Repayments of Long-term Debt	0	0
Debt financing costs	0	0
Payments for Repurchase of Common Stock	0	0
Payments of Dividends	0	0
Proceeds from the exercise of stock options	0	0
Net intercompany loan borrowings (repayments)	0	0
Equity from parent	1,641
Payments to Acquire Additional Interest in Subsidiaries		0
Change in noncontrolling interest share	0
Dividends paid to noncontrolling interest	0	0
Dividend from Adient spin-off	0
Cash transferred to Adient related to spin-off	0
Payments for (Proceeds from) Previous Acquisition	0
Other	0	0
Net cash provided by financing activities	1,641	0
Effect of exchange rate changes on cash and cash equivalents	0	0
Cash And Cash Equivalents Held For Sale	0	0
Increase (decrease) in cash and cash equivalents	107	0
Cash and cash equivalents	107	0	0
Tyco International Finance S.A.
Condensed Cash Flow Statements, Captions [Line Items]
Net Cash Provided by Operating Activities	142	639
Capital expenditures	0	0
Sale of property, plant and equipment	0	0
Acquisition of business, net of cash acquired	(6)	0
Business divestitures	0	0
Changes in long-term investments	(11)	57
Net change in intercompany loans	0	10
Intercompany investment in subsidiaries	(100)
Other		0
Net cash used in investing activities	(117)	67
Increase (decrease) in short-term debt - net	0	(462)
Increase in long-term debt	0	0
Repayments of Long-term Debt	(20)	0
Debt financing costs	0	0
Payments for Repurchase of Common Stock	0	0
Payments of Dividends	0	0
Proceeds from the exercise of stock options	0	0
Net intercompany loan borrowings (repayments)	57	0
Equity from parent	76
Payments to Acquire Additional Interest in Subsidiaries		0
Change in noncontrolling interest share	0
Dividends paid to noncontrolling interest	0	0
Dividend from Adient spin-off	0
Cash transferred to Adient related to spin-off	0
Payments for (Proceeds from) Previous Acquisition	0
Other	0	0
Net cash provided by financing activities	113	(462)
Effect of exchange rate changes on cash and cash equivalents	0	0
Cash And Cash Equivalents Held For Sale	0	0
Increase (decrease) in cash and cash equivalents	138	244
Cash and cash equivalents	$ 382	$ 244	$ 0