CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Sales	$ 983	$ 871	$ 1,872	$ 1,772
Cost of sales	(835)	(757)	(1,609)	(1,531)
GROSS PROFIT	148	114	263	241
Selling, general and administrative	(69)	(59)	(134)	(129)
Income from WABCO distribution termination	0	265	0	265
Other operating expense, net	(2)	(10)	(9)	(15)
OPERATING INCOME	77	310	120	362
Other income, net	23	14	37	24
Equity in earnings of affiliates	5	6	16	12
Interest expense, net	(17)	(16)	(45)	(30)
INCOME BEFORE INCOME TAXES	88	314	128	368
Provision for income taxes	(22)	(73)	(29)	(86)
INCOME FROM CONTINUING OPERATIONS	66	241	99	282
INCOME FROM DISCONTINUED OPERATIONS, net of tax	0	1	0	1
NET INCOME	66	242	99	283
Less: Net income attributable to noncontrolling interests	(3)	(1)	(4)	(3)
NET INCOME ATTRIBUTABLE TO MERITOR, INC.	63	241	95	280
NET INCOME ATTRIBUTABLE TO MERITOR, INC.
Net income from continuing operations	63	240	95	279
Income from discontinued operations	0	1	0	1
Net income	$ 63	$ 241	$ 95	$ 280
BASIC EARNINGS PER SHARE
Continuing operations (in usd per share)	$ 0.87	$ 3.27	$ 1.31	$ 3.68
Discontinued operations (in usd per share)	0	0.01	0	0.01
Basic earnings per share (in usd per share)	0.87	3.28	1.31	3.69
DILUTED EARNINGS PER SHARE
Continuing operations (in usd per share)	0.86	3.19	1.30	3.58
Discontinued operations (in usd per share)	0	0.01	0	0.01
Diluted earnings per share (in usd per share)	$ 0.86	$ 3.20	$ 1.30	$ 3.59
Basic average common shares outstanding (in shares)	72.4	73.4	72.3	75.8
Diluted average common shares outstanding (in shares)	73.4	75.3	73.3	78.0