Equity and Noncontrolling Interests - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Mar. 31, 2018		Mar. 31, 2017		Mar. 31, 2018		Mar. 31, 2017		Sep. 30, 2017
Realized and unrealized gains (losses) on derivatives
Current period changes in fair value	$ (10)		$ (8)		$ (11)		$ (4)
Pension and postretirement plans
Other changes	0		0
Accumulated other comprehensive loss	(254)		(987)		(254)		(987)		$ (473)
Treasury Stock, Value, Acquired, Cost Method	49		119		199		119
Foreign currency translation adjustments
Foreign currency translation adjustments
Balance at beginning of period	(423)		(1,248)		(481)		(1,152)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent	168		241		226		(418)
Adient spin-off impact					0		563
Balance at end of period	(255)		(1,007)		(255)		(1,007)
Aggregate adjustment for period, tax effect	0	[1]	0	[1]	1		5
Adient spin-off impact, tax effect					0		0
Realized and unrealized gains (losses) on derivatives
Realized and unrealized gains (losses) on derivatives
Balance at beginning of period	7		20		6		4
Current period changes in fair value	(4)		1		2		7
Reclassification to income	(2)		(7)		(7)		(13)
Adient spin-off impact					0		16
Balance at end of period	1		14		1		14
Current period changes in fair value, tax effect	(2)		0		1		4
Reclassifcation to income, tax effect	0	[2]	(4)	[2]	(2)	[1]	(7)	[1]
Adient spin-off, tax effect					0		6
Realized and unrealized gains (losses) on marketable securities
Realized and unrealized gains (losses) on marketable securities
Balance at beginning of period	4		(3)		4		(1)
Current period changes in fair value	(2)		11		(2)		9
Balance at end of period	2		8		2		8
Current period changes in fair value, tax effect	0		0		0		0
Pension and postretirement plans
Pension and postretirement plans
Balance at beginning of period	(2)		(2)		(2)		(4)
Adient spin-off impact					0		2
Balance at end of period	$ (2)		$ (2)		(2)		(2)
Adient spin-off, tax effect					0		$ 0
Scott Safety business [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax					$ 12

[1] * During the six months ended March 31, 2018, $12 million of cumulative CTA was recognized as part of the divestiture-related gain recognized as a result of the divestiture of Scott Safety.

[2] ** Refer to Note 15, "Derivative Instruments and Hedging Activities," of the notes to consolidated financial statements for disclosure of the line items in the consolidated statements of income affected by reclassifications from AOCI into income related to derivatives.