SUPPLEMENTAL PARENT AND GUARANTOR CONDENSED CONSOLIDATING FINANCIAL STATEMENTS SUPPLEMENTAL PARENT AND GUARANTOR CONDENSED CONSOLIDATING FINANCIAL STATEMENTS (Details 1) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	$ (22)	$ 14	$ 43	$ 30	$ 4	$ 234	$ 3	$ 13	$ 65	$ 254	$ (20)
Other comprehensive income (loss)									(19)	(15)	181
Total comprehensive income									46	239	161
Less: Comprehensive income (loss) attributable to noncontrolling interest									1	(5)	(2)
Comprehensive income attributable to Meritor, Inc.									47	234	159
Parent
Condensed Financial Statements, Captions [Line Items]
Net income (loss)									64	249	(22)
Other comprehensive income (loss)									(19)	(15)	181
Total comprehensive income									45	234	159
Less: Comprehensive income (loss) attributable to noncontrolling interest									2	0	0
Comprehensive income attributable to Meritor, Inc.									47	234	159
Guarantors
Condensed Financial Statements, Captions [Line Items]
Net income (loss)									262	479	281
Other comprehensive income (loss)									(61)	(54)	13
Total comprehensive income									201	425	294
Less: Comprehensive income (loss) attributable to noncontrolling interest									0	0	0
Comprehensive income attributable to Meritor, Inc.									201	425	294
Non- Guarantors
Condensed Financial Statements, Captions [Line Items]
Net income (loss)									50	79	(162)
Other comprehensive income (loss)									(16)	25	(12)
Total comprehensive income									34	104	(174)
Less: Comprehensive income (loss) attributable to noncontrolling interest									(1)	(5)	(2)
Comprehensive income attributable to Meritor, Inc.									33	99	(176)
Elims
Condensed Financial Statements, Captions [Line Items]
Net income (loss)									(311)	(553)	(117)
Other comprehensive income (loss)									77	29	(1)
Total comprehensive income									(234)	(524)	(118)
Less: Comprehensive income (loss) attributable to noncontrolling interest									0	0	0
Comprehensive income attributable to Meritor, Inc.									$ (234)	$ (524)	$ (118)