QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Quarterly Financial Information Disclosure [Abstract]
Sales	$ 933	$ 979	$ 954	$ 900	$ 902	$ 986	$ 900	$ 884	$ 3,766	$ 3,672	$ 4,384
Cost of sales	(793)	(855)	(836)	(795)	(793)	(877)	(805)	(802)	(3,279)	(3,277)	(3,902)
Gross margin	140	124	118	105	109	109	95	82	487	395	482
Provision for income taxes	0	(12)	(8)	(11)	(45)	(1)	(7)	(11)	(31)	(64)	(57)
Net income (loss)	4	234	3	13	43	(39)	(4)	(20)	254	(20)	63
Income (loss) from continuing operations attributable to Meritor, Inc.	29	237	1	12	40	(37)	(3)	(15)	279	(15)	69
NET INCOME (LOSS) ATTRIBUTABLE TO MERITOR, INC.	$ 3	$ 234	$ 1	$ 11	$ 41	$ (39)	$ (3)	$ (21)	$ 249	$ (22)	$ 52
Basic income (loss) per share from continuing operations	$ 0.30	$ 2.43	$ 0.01	$ 0.12	$ 0.41	$ (0.38)	$ (0.03)	$ (0.16)	$ 2.86	$ (0.15)	$ 0.72
Diluted income (loss) per share from continuing operations	$ 0.29	$ 2.34	$ 0.01	$ 0.12	$ 0.41	$ (0.38)	$ (0.03)	$ (0.16)	$ 2.81	$ (0.15)	$ 0.71