Supplemental Guarantor Condensed Consolidating Financial Statements (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Mar. 31, 2015	Mar. 31, 2014		Mar. 31, 2015	Mar. 31, 2014
Amount of restricted net assets for consolidated and unconsolidated subsidiaries	$ 31			$ 31
Sales
Total Sales	864	954		1,743	1,854
Cost of sales	(749)	(836)		(1,513)	(1,631)
GROSS MARGIN	115	118		230	223
Selling, general and administrative	(57)	(66)		(122)	(125)
Restructuring costs	(3)	(2)	[1]	(6)	(3)
Other operating expense	0	0		1	(1)
OPERATING INCOME (LOSS)	55	50		103	94
Other income, net	2	0		4	0
Equity in earnings of affiliates	9	9		18	17
Interest expense, net	(21)	(48)	[1]	(40)	(75)
INCOME BEFORE INCOME TAXES	45	11		85	36
Provision for income taxes	(6)	(8)	[1]	(13)	(19)
Equity income from continuing operations of subsidiaries	0	0		0	0
INCOME FROM CONTINUING OPERATIONS	39	3		72	17
INCOME (LOSS) FROM DISCONTINUED OPERATIONS, net of tax	4	0		1	(1)
NET INCOME	43	3		73	16
Less: Net income attributable to noncontrolling interests	0	(2)	[1]	(1)	(4)
NET INCOME ATTRIBUTABLE TO MERITOR, INC.	43	1		72	12
External Sales
Sales
Total Sales	864	954		1,743	1,854
Subsidiaries Sales
Sales
Total Sales	0	0		0	0
Parent
Sales
Total Sales	0	0		0	0
Cost of sales	(10)	(13)		(24)	(26)
GROSS MARGIN	(10)	(13)		(24)	(26)
Selling, general and administrative	(16)	(23)		(34)	(40)
Restructuring costs	(1)	(1)		(1)	(1)
Other operating expense	0				0
OPERATING INCOME (LOSS)	(27)	(37)		(59)	(67)
Other income, net	37	39		37	39
Equity in earnings of affiliates	0	0		0	0
Interest expense, net	(29)	(54)		(58)	(88)
INCOME BEFORE INCOME TAXES	(19)	(52)		(80)	(116)
Provision for income taxes	(1)	0		(1)	0
Equity income from continuing operations of subsidiaries	59	53		152	129
INCOME FROM CONTINUING OPERATIONS	39	1		71	13
INCOME (LOSS) FROM DISCONTINUED OPERATIONS, net of tax	4	0		1	(1)
NET INCOME	43	1		72	12
Less: Net income attributable to noncontrolling interests	0	0		0	0
NET INCOME ATTRIBUTABLE TO MERITOR, INC.	43	1		72	12
Parent | External Sales
Sales
Total Sales	0	0		0	0
Parent | Subsidiaries Sales
Sales
Total Sales	0	0		0	0
Guarantors
Sales
Total Sales	449	381		882	723
Cost of sales	(380)	(326)		(751)	(623)
GROSS MARGIN	69	55		131	100
Selling, general and administrative	(26)	(22)		(54)	(45)
Restructuring costs	0	0		(3)	0
Other operating expense	0				(1)
OPERATING INCOME (LOSS)	43	33		74	54
Other income, net	(9)	(8)		(9)	(8)
Equity in earnings of affiliates	8	6		15	12
Interest expense, net	6	8		13	17
INCOME BEFORE INCOME TAXES	48	39		93	75
Provision for income taxes	0	1		0	(1)
Equity income from continuing operations of subsidiaries	8	10		53	48
INCOME FROM CONTINUING OPERATIONS	56	50		146	122
INCOME (LOSS) FROM DISCONTINUED OPERATIONS, net of tax	5	0		2	(1)
NET INCOME	61	50		148	121
Less: Net income attributable to noncontrolling interests	0	0		0	0
NET INCOME ATTRIBUTABLE TO MERITOR, INC.	61	50		148	121
Guarantors | External Sales
Sales
Total Sales	418	348		821	657
Guarantors | Subsidiaries Sales
Sales
Total Sales	31	33		61	66
Non-Guarantors
Sales
Total Sales	463	621		955	1,226
Cost of sales	(407)	(545)		(832)	(1,077)
GROSS MARGIN	56	76		123	149
Selling, general and administrative	(15)	(21)		(34)	(40)
Restructuring costs	(2)	(1)		(2)	(2)
Other operating expense	0			1	0
OPERATING INCOME (LOSS)	39	54		88	107
Other income, net	(26)	(31)		(24)	(31)
Equity in earnings of affiliates	1	3		3	5
Interest expense, net	2	(2)		5	(4)
INCOME BEFORE INCOME TAXES	16	24		72	77
Provision for income taxes	(5)	(9)		(12)	(18)
Equity income from continuing operations of subsidiaries	0	0		0	0
INCOME FROM CONTINUING OPERATIONS	11	15		60	59
INCOME (LOSS) FROM DISCONTINUED OPERATIONS, net of tax	3	0		0	(1)
NET INCOME	14	15		60	58
Less: Net income attributable to noncontrolling interests	0	(2)		(1)	(4)
NET INCOME ATTRIBUTABLE TO MERITOR, INC.	14	13		59	54
Non-Guarantors | External Sales
Sales
Total Sales	446	606		922	1,197
Non-Guarantors | Subsidiaries Sales
Sales
Total Sales	17	15		33	29
Elims
Sales
Total Sales	(48)	(48)		(94)	(95)
Cost of sales	48	48		94	95
GROSS MARGIN	0	0		0	0
Selling, general and administrative	0	0		0	0
Restructuring costs	0	0		0	0
Other operating expense	0				0
OPERATING INCOME (LOSS)	0	0		0	0
Other income, net	0	0		0	0
Equity in earnings of affiliates	0	0		0	0
Interest expense, net	0	0		0	0
INCOME BEFORE INCOME TAXES	0	0		0	0
Provision for income taxes	0	0		0	0
Equity income from continuing operations of subsidiaries	(67)	(63)		(205)	(177)
INCOME FROM CONTINUING OPERATIONS	(67)	(63)		(205)	(177)
INCOME (LOSS) FROM DISCONTINUED OPERATIONS, net of tax	(8)	0		(2)	2
NET INCOME	(75)	(63)		(207)	(175)
Less: Net income attributable to noncontrolling interests	0	0		0	0
NET INCOME ATTRIBUTABLE TO MERITOR, INC.	(75)	(63)		(207)	(175)
Elims | External Sales
Sales
Total Sales	0	0		0	0
Elims | Subsidiaries Sales
Sales
Total Sales	$ (48)	$ (48)		$ (94)	$ (95)

[1] Amounts for prior periods have been recast for discontinued operations.