DOCUMENT AND ENTITY INFORMATION - shares	3 Months Ended
	Dec. 31, 2017	Jan. 30, 2018
Document and Entity Information [Abstract]
Entity registrant name	MERITOR INC
Entity central index key	0001113256
Current fiscal year end date	--09-30
Entity filer category	Large Accelerated Filer
Trading symbol	MTOR
Entity common stock, shares outstanding		89,184,543
Document period end date	Dec. 31, 2017
Document fiscal year focus	2018
Document type	10-Q
Document fiscal period focus	Q1
Amendment flag	false