CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Sales	$ 1,166	$ 1,129	$ 3,360	$ 3,098
Cost of sales	(987)	(959)	(2,866)	(2,625)
GROSS MARGIN	179	170	494	473
Selling, general and administrative	(73)	(76)	(180)	(218)
Restructuring	1	(3)	2	(6)
Other operating expense, net	(3)	0	(3)	(12)
OPERATING INCOME (LOSS)	104	91	313	237
Other income, net	10	9	30	24
Equity in earnings of affiliates	9	9	24	20
Interest income (expense), net	(14)	(14)	(43)	(54)
INCOME (LOSS) BEFORE INCOME TAXES	109	95	324	227
Benefit (provision) for income taxes	(21)	(26)	(69)	(131)
INCOME FROM CONTINUING OPERATIONS	88	69	255	96
LOSS FROM DISCONTINUED OPERATIONS, net of tax	1	(2)	0	(3)
NET INCOME	89	67	255	93
Less: Net income attributable to noncontrolling interests	(3)	(3)	(7)	(8)
NET INCOME ATTRIBUTABLE TO MERITOR, INC.	86	64	248	85
NET INCOME (LOSS) ATTRIBUTABLE TO MERITOR, INC.
Net income from continuing operations	85	66	248	88
Income (Loss) from discontinued operations	1	(2)	0	(3)
NET INCOME ATTRIBUTABLE TO MERITOR, INC.	$ 86	$ 64	$ 248	$ 85
BASIC EARNINGS (LOSS) PER SHARE
Continuing operations (in usd per share)	$ 1.02	$ 0.76	$ 2.96	$ 1.00
Discontinued operations (in usd per share)	0.01	(0.02)	0	(0.03)
Basic earnings per share (in usd per share)	1.03	0.74	2.96	0.97
DILUTED EARNINGS (LOSS) PER SHARE
Continuing operations (in usd per share)	0.99	0.73	2.86	0.96
Discontinued operations (in usd per share)	0.01	(0.02)	0	(0.03)
Diluted earnings per share (in usd per share)	$ 1.00	$ 0.71	$ 2.86	$ 0.93
Basic average common shares outstanding (in shares)	83.0	87.2	83.7	88.1
Diluted average common shares outstanding (in shares)	85.6	89.8	86.6	91.2