Supplemental Guarantor Condensed Consolidating Financial Statements (Details 1) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Sep. 30, 2011	Mar. 31, 2011	Sep. 30, 2010
CURRENT ASSETS
Cash and cash equivalents	$ 109	$ 217	$ 195	$ 343
Receivables, net	703	712
Inventories	489	460
Other current assets	65	70
TOTAL CURRENT ASSETS	1,366	1,459
NET PROPERTY	404	421
GOODWILL	433	431
OTHER ASSETS	362	352
TOTAL ASSETS	2,565	2,663
CURRENT LIABILITIES
Short-term debt	21	84
Accounts payable	809	841
Other current liabilities	343	328
TOTAL CURRENT LIABILITIES	1,173	1,253
LONG-TERM DEBT	954	950
RETIREMENT BENEFITS	1,064	1,096
OTHER LIABILITIES	319	325
EQUITY (DEFICIT) ATTRIBUTABLE TO MERITOR, INC.	(985)	(995)
NONCONTROLLING INTERESTS	40	34
TOTAL LIABILITIES AND EQUITY (DEFICIT)	2,565	2,663
Parent Company [Member]
CURRENT ASSETS
Cash and cash equivalents	10	92	62	47
Receivables, net	1	1
Inventories	0	0
Other current assets	5	6
TOTAL CURRENT ASSETS	16	99
NET PROPERTY	12	9
GOODWILL	0	0
OTHER ASSETS	43	44
INVESTMENTS IN SUBSIDIARIES	1,371	1,265
TOTAL ASSETS	1,442	1,417
CURRENT LIABILITIES
Short-term debt	2	84
Accounts payable	57	52
Other current liabilities	108	92
TOTAL CURRENT LIABILITIES	167	228
LONG-TERM DEBT	944	942
RETIREMENT BENEFITS	943	953
INTERCOMPANY PAYABLE (RECEIVABLE)	302	202
OTHER LIABILITIES	71	87
EQUITY (DEFICIT) ATTRIBUTABLE TO MERITOR, INC.	(985)	(995)
NONCONTROLLING INTERESTS	0	0
TOTAL LIABILITIES AND EQUITY (DEFICIT)	1,442	1,417
Guarantor Subsidiaries [Member]
CURRENT ASSETS
Cash and cash equivalents	8	4	4	6
Receivables, net	26	24
Inventories	200	181
Other current assets	19	17
TOTAL CURRENT ASSETS	253	226
NET PROPERTY	141	138
GOODWILL	276	275
OTHER ASSETS	185	179
INVESTMENTS IN SUBSIDIARIES	231	154
TOTAL ASSETS	1,086	972
CURRENT LIABILITIES
Short-term debt	0	0
Accounts payable	219	225
Other current liabilities	58	67
TOTAL CURRENT LIABILITIES	277	292
LONG-TERM DEBT	2	0
RETIREMENT BENEFITS	0	0
INTERCOMPANY PAYABLE (RECEIVABLE)	(797)	(820)
OTHER LIABILITIES	170	165
EQUITY (DEFICIT) ATTRIBUTABLE TO MERITOR, INC.	1,434	1,335
NONCONTROLLING INTERESTS	0	0
TOTAL LIABILITIES AND EQUITY (DEFICIT)	1,086	972
Non-Guarantor Subsidiaries [Member]
CURRENT ASSETS
Cash and cash equivalents	91	121	129	290
Receivables, net	676	687
Inventories	289	279
Other current assets	41	47
TOTAL CURRENT ASSETS	1,097	1,134
NET PROPERTY	251	274
GOODWILL	157	156
OTHER ASSETS	134	129
INVESTMENTS IN SUBSIDIARIES	0	0
TOTAL ASSETS	1,639	1,693
CURRENT LIABILITIES
Short-term debt	19	0
Accounts payable	533	564
Other current liabilities	177	169
TOTAL CURRENT LIABILITIES	729	733
LONG-TERM DEBT	8	8
RETIREMENT BENEFITS	121	143
INTERCOMPANY PAYABLE (RECEIVABLE)	495	618
OTHER LIABILITIES	78	73
EQUITY (DEFICIT) ATTRIBUTABLE TO MERITOR, INC.	168	84
NONCONTROLLING INTERESTS	40	34
TOTAL LIABILITIES AND EQUITY (DEFICIT)	1,639	1,693
Elims [Member]
CURRENT ASSETS
Cash and cash equivalents	0	0	0	0
Receivables, net	0	0
Inventories	0	0
Other current assets	0	0
TOTAL CURRENT ASSETS	0	0
NET PROPERTY	0	0
GOODWILL	0	0
OTHER ASSETS	0	0
INVESTMENTS IN SUBSIDIARIES	(1,602)	(1,419)
TOTAL ASSETS	(1,602)	(1,419)
CURRENT LIABILITIES
Short-term debt	0	0
Accounts payable	0	0
Other current liabilities	0	0
TOTAL CURRENT LIABILITIES	0	0
LONG-TERM DEBT	0	0
RETIREMENT BENEFITS	0	0
INTERCOMPANY PAYABLE (RECEIVABLE)	0	0
OTHER LIABILITIES	0	0
EQUITY (DEFICIT) ATTRIBUTABLE TO MERITOR, INC.	(1,602)	(1,419)
NONCONTROLLING INTERESTS	0	0
TOTAL LIABILITIES AND EQUITY (DEFICIT)	(1,602)	(1,419)
Consolidated [Member]
CURRENT ASSETS
Cash and cash equivalents	109	217	195	343
Receivables, net	703	712
Inventories	489	460
Other current assets	65	70
TOTAL CURRENT ASSETS	1,366	1,459
NET PROPERTY	404	421
GOODWILL	433	431
OTHER ASSETS	362	352
INVESTMENTS IN SUBSIDIARIES	0	0
TOTAL ASSETS	2,565	2,663
CURRENT LIABILITIES
Short-term debt	21	84
Accounts payable	809	841
Other current liabilities	343	328
TOTAL CURRENT LIABILITIES	1,173	1,253
LONG-TERM DEBT	954	950
RETIREMENT BENEFITS	1,064	1,096
INTERCOMPANY PAYABLE (RECEIVABLE)	0	0
OTHER LIABILITIES	319	325
EQUITY (DEFICIT) ATTRIBUTABLE TO MERITOR, INC.	(985)	(995)
NONCONTROLLING INTERESTS	40	34
TOTAL LIABILITIES AND EQUITY (DEFICIT)	$ 2,565	$ 2,663