DOCUMENT AND ENTITY INFORMATION - USD ($)	12 Months Ended
	Sep. 30, 2017	Nov. 14, 2017	Mar. 31, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	MERITOR INC
Entity Central Index Key	0001113256
Current Fiscal Year End Date	--10-01
Entity Filer Category	Large Accelerated Filer
Trading Symbol	MTOR
Entity Common Stock, Shares Outstanding		88,583,473
Document Period End Date	Oct. 01, 2017
Document Type	10-K
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2017
Amendment Flag	false
Entity Well-Known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 1,487,830,039