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.