TIFSA Condensed Statement of Cash Flows (Details) - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Sep. 30, 2017	Sep. 30, 2016
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided (used) by operating activities	$ 533	$ (1,519)
Capital expenditures	(497)	(634)
Sale of property, plant and equipment	10	18
Acquisition of businesses, net of cash acquired	(15)	(6)
Business divestitures	2,114	180
Changes in long-term investments	(14)	(30)
Net change in intercompany loans	0	0
Intercompany investment in subsidiaries		0
Net cash used by investing activities	1,598	(472)
Increase (decrease) in short-term debt - net	(100)	55
Increase in long-term debt	886	1,552
Repayment of long-term debt	(2,328)	(831)
Debt financing costs	(4)	(17)
Stock repurchases	(199)	(119)
Payment of cash dividends	(473)	(235)
Proceeds from the exercise of stock options	36	88
Employee equity-based compensation withholding taxes	(37)	(33)
Net change in intercompany loans payable	0	0
Increase in equity from parent		0
Dividends paid to noncontrolling interests	(46)	(78)
Dividend from Adient spin-off	0	2,050
Cash transferred to Adient related to spin-off	0	(665)
Cash paid related to prior acquistions	0	(37)
Other	11	14
Net cash provided by financing activities	(2,254)	1,744
Effect of exchange rate changes on cash and cash equivalents	61	(25)
Changes in cash held for sale	9	105
Increase (decrease) in cash and cash equivalents	(53)	(167)
Cash and cash equivalents, at carrying value	268	412	$ 321	$ 579
Consolidation, Eliminations [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided (used) by operating activities	0	0
Capital expenditures	0	0
Sale of property, plant and equipment	0	0
Acquisition of businesses, net of cash acquired	0	0
Business divestitures	0	0
Changes in long-term investments	0	0
Net change in intercompany loans	(598)	(175)
Intercompany investment in subsidiaries		(3,716)
Net cash used by investing activities	(598)	3,541
Increase (decrease) in short-term debt - net	(604)	(361)
Increase in long-term debt	0	0
Repayment of long-term debt	0	0
Debt financing costs	0	0
Stock repurchases	0	0
Payment of cash dividends	0	0
Proceeds from the exercise of stock options	0	0
Employee equity-based compensation withholding taxes	0	0
Net change in intercompany loans payable	598	175
Increase in equity from parent		(3,716)
Dividends paid to noncontrolling interests	0	0
Dividend from Adient spin-off		0
Cash transferred to Adient related to spin-off		0
Cash paid related to prior acquistions		0
Other	0	0
Net cash provided by financing activities	(6)	(3,902)
Effect of exchange rate changes on cash and cash equivalents	0	0
Changes in cash held for sale	0	0
Increase (decrease) in cash and cash equivalents	(604)	(361)
Cash and cash equivalents, at carrying value	(1,490)	(361)	(886)	0
Parent Company [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided (used) by operating activities	(342)	62
Capital expenditures	0	0
Sale of property, plant and equipment	0	0
Acquisition of businesses, 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		(1,924)
Net cash used by investing activities	300	(1,924)
Increase (decrease) in short-term debt - net	687	885
Increase in long-term debt	885	1,544
Repayment of long-term debt	(307)	(46)
Debt financing costs	(4)	(17)
Stock repurchases	(199)	(119)
Payment of cash dividends	(473)	(235)
Proceeds from the exercise of stock options	36	88
Employee equity-based compensation withholding taxes	0	0
Net change in intercompany loans payable	(583)	(165)
Increase in equity from parent		0
Dividends paid to noncontrolling interests	0	0
Dividend from Adient spin-off		0
Cash transferred to Adient related to spin-off		(87)
Cash paid related to prior acquistions		0
Other	0	6
Net cash provided by financing activities	42	1,854
Effect of exchange rate changes on cash and cash equivalents	0	0
Changes in cash held for sale	0	0
Increase (decrease) in cash and cash equivalents	0	(8)
Cash and cash equivalents, at carrying value	0	3	0	11
Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided (used) by operating activities	188	0
Capital expenditures	0	0
Sale of property, plant and equipment	0	0
Acquisition of businesses, 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)
Net cash used by investing activities	0	(1,716)
Increase (decrease) in short-term debt - net	9	76
Increase in long-term debt	0	0
Repayment of long-term debt	0	0
Debt financing costs	0	0
Stock repurchases	0	0
Payment of cash dividends	0	0
Proceeds from the exercise of stock options	0	0
Employee equity-based compensation withholding taxes	0	0
Net change in intercompany loans payable	0	0
Increase in equity from parent		1,640
Dividends paid to noncontrolling interests	0	0
Dividend from Adient spin-off		0
Cash transferred to Adient related to spin-off		0
Cash paid related to prior acquistions		0
Other	0	0
Net cash provided by financing activities	9	1,716
Effect of exchange rate changes on cash and cash equivalents	0	0
Changes in cash held for sale	0	0
Increase (decrease) in cash and cash equivalents	197	0
Cash and cash equivalents, at carrying value	304	0	107	0
Subsidiary Issuer [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided (used) by operating activities	82	67
Capital expenditures	0	0
Sale of property, plant and equipment	0	0
Acquisition of businesses, net of cash acquired	0	(6)
Business divestitures	0	0
Changes in long-term investments	0	(11)
Net change in intercompany loans	(285)	10
Intercompany investment in subsidiaries		(76)
Net cash used by investing activities	(285)	(83)
Increase (decrease) in short-term debt - net	0	0
Increase in long-term debt	0	0
Repayment of long-term debt	(18)	(16)
Debt financing costs	0	0
Stock repurchases	0	0
Payment of cash dividends	0	0
Proceeds from the exercise of stock options	0	0
Employee equity-based compensation withholding taxes	0	0
Net change in intercompany loans payable	0	0
Increase in equity from parent		76
Dividends paid to noncontrolling interests	0	0
Dividend from Adient spin-off		0
Cash transferred to Adient related to spin-off		0
Cash paid related to prior acquistions		0
Other	0	0
Net cash provided by financing activities	(18)	60
Effect of exchange rate changes on cash and cash equivalents	0	0
Changes in cash held for sale	0	0
Increase (decrease) in cash and cash equivalents	(221)	44
Cash and cash equivalents, at carrying value	161	288	382	244
Non-Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided (used) by operating activities	605	(1,648)
Capital expenditures	(497)	(634)
Sale of property, plant and equipment	10	18
Acquisition of businesses, net of cash acquired	(15)	0
Business divestitures	2,114	180
Changes in long-term investments	(14)	(19)
Net change in intercompany loans	583	165
Intercompany investment in subsidiaries		0
Net cash used by investing activities	2,181	(290)
Increase (decrease) in short-term debt - net	(192)	(545)
Increase in long-term debt	1	8
Repayment of long-term debt	(2,003)	(769)
Debt financing costs	0	0
Stock repurchases	0	0
Payment of cash dividends	0	0
Proceeds from the exercise of stock options	0	0
Employee equity-based compensation withholding taxes	(37)	(33)
Net change in intercompany loans payable	(15)	(10)
Increase in equity from parent		2,000
Dividends paid to noncontrolling interests	(46)	(78)
Dividend from Adient spin-off		2,050
Cash transferred to Adient related to spin-off		(578)
Cash paid related to prior acquistions		(37)
Other	11	8
Net cash provided by financing activities	(2,281)	2,016
Effect of exchange rate changes on cash and cash equivalents	61	(25)
Changes in cash held for sale	9	105
Increase (decrease) in cash and cash equivalents	575	158
Cash and cash equivalents, at carrying value	$ 1,293	$ 482	$ 718	$ 324