CONSOLIDATED STATEMENT OF OPERATIONS - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Sales	$ 3,347	$ 3,199	$ 3,505
Cost of sales	(2,863)	(2,763)	(3,043)
GROSS MARGIN	484	436	462
Selling, general and administrative	(264)	(213)	(243)
Pension settlement losses	0	0	(59)
Restructuring costs	(6)	(16)	(16)
Goodwill impairment	0	0	(15)
Other operating expense, net	(7)	(3)	(1)
OPERATING INCOME (LOSS)	207	204	128
Other income (expense), net	2	(1)	5
Gain on sale of equity investment	243	0	0
Equity in earnings of affiliates	48	36	39
Interest expense, net	(119)	(84)	(105)
INCOME (LOSS) BEFORE INCOME TAXES	381	155	67
Benefit (provision) for income taxes	(52)	424	(1)
INCOME FROM CONTINUING OPERATIONS	329	579	66
LOSS FROM DISCONTINUED OPERATIONS, net of tax	(1)	(4)	(1)
NET INCOME	328	575	65
Less: Net income attributable to noncontrolling interests	(4)	(2)	(1)
NET INCOME ATTRIBUTABLE TO MERITOR, INC.	324	573	64
NET INCOME ATTRIBUTABLE TO MERITOR, INC.
Net income from continuing operations	325	577	65
Loss from discontinued operations	(1)	(4)	(1)
Net income	$ 324	$ 573	$ 64
BASIC EARNINGS (LOSS) PER SHARE
Basic earnings (loss) per share from continuing operations (in dollars per share)	$ 3.69	$ 6.40	$ 0.67
Basic earnings (loss) per share from discontinued operations (in dollars per share)	(0.01)	(0.04)	(0.01)
Basic earnings (loss) per share (in dollars per share)	3.68	6.36	0.66
DILUTED EARNINGS (LOSS) PER SHARE
Diluted earnings (loss) per share from continuing operations (in dollars per share)	3.60	6.27	0.65
Diluted earnings (loss) per share from discontinued operations (in dollars per share)	(0.01)	(0.04)	(0.01)
Diluted earnings (loss) per share (in dollars per share)	$ 3.59	$ 6.23	$ 0.64
Basic average common shares outstanding (in shares)	88.0	90.1	96.9
Diluted average common shares outstanding (in shares)	90.2	92.0	100.1