BUSINESS SEGMENT INFORMATION (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
Segment Reporting Information [Line Items]
Interest expense, net									$ (105)	$ (130)	$ (126)
Provision for income taxes	$ 18	$ (6)	$ (6)	$ (7)	$ 0	$ (12)	$ (8)	$ (11)	(1)	(31)	(64)
Depreciation and amortization									(65)	(67)	(67)
Restructuring costs	(1)	(9)	(3)	(3)	(7)		(2)	(1)	(16)	(10)	(23)
Pension settlement losses									(59)	0	(109)
Gain on sale of equity investment									0	0	125
Noncontrolling interests									(1)	(5)	(2)
Income (loss) from continuing operations attributable to Meritor, Inc.	$ (21)	$ 15	$ 39	$ 32	$ 29	$ 237	$ 1	$ 12	65	279	(15)
Commercial Truck & Industrial
Segment Reporting Information [Line Items]
Restructuring costs									(14)	(8)	(17)
Aftermarket & Trailer
Segment Reporting Information [Line Items]
Restructuring costs									0	(1)	(3)
Operating Segments
Segment Reporting Information [Line Items]
Segment EBITDA									339	324	279
Depreciation and amortization									(65)	(67)	(67)
Operating Segments | Commercial Truck & Industrial
Segment Reporting Information [Line Items]
Segment EBITDA									216	218	192
Depreciation and amortization									(59)	(61)	(60)
Operating Segments | Aftermarket & Trailer
Segment Reporting Information [Line Items]
Segment EBITDA									123	106	87
Depreciation and amortization									(6)	(6)	(7)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Unallocated legacy and corporate expense, net									(5)	(10)	(15)
Interest expense, net									(105)	(130)	(126)
Provision for income taxes									(1)	(31)	(64)
Depreciation and amortization									(65)	(67)	(67)
Loss on sale of receivables									(5)	(8)	(6)
Restructuring costs									(16)	(10)	(23)
Litigation Settlement, Amount, After Taxes And Fees Incurred In Current Fiscal Year									0	208	0
Specific warranty contingency, net of supplier recovery									0	8	(7)
Pension settlement losses									(59)	0	(109)
Gain on sale of equity investment									0	0	125
Gain on sale of property									(17)	0	0
Noncontrolling interests									$ (1)	$ (5)	$ (2)