Supplemental Guarantor Condensed Consolidating Financial Statements (Details 1) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 6 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Mar. 31, 2015
Mar. 31, 2014
Condensed Statement Of Income Captions [Line Items]        
Net income $ 43 $ 3 $ 73 $ 16
Other comprehensive income (loss) (22) 22 (45) 22
Total comprehensive income 21 25 28 38
Less: Comprehensive income attributable to noncontrolling interests 0 (2) 0 (4)
Comprehensive income attributable to Meritor, Inc. 21 23 28 34
Parent        
Condensed Statement Of Income Captions [Line Items]        
Net income 43 1 72 12
Other comprehensive income (loss) (22) 22 (44) 22
Total comprehensive income 21 23 28 34
Less: Comprehensive income attributable to noncontrolling interests 0 0 0 0
Comprehensive income attributable to Meritor, Inc. 21 23 28 34
Guarantors        
Condensed Statement Of Income Captions [Line Items]        
Net income 61 50 148 121
Other comprehensive income (loss) (65) 5 (92) 10
Total comprehensive income (4) 55 56 131
Less: Comprehensive income attributable to noncontrolling interests 0 0 0 0
Comprehensive income attributable to Meritor, Inc. (4) 55 56 131
Non-Guarantors        
Condensed Statement Of Income Captions [Line Items]        
Net income 14 15 60 58
Other comprehensive income (loss) 27 11 18 0
Total comprehensive income 41 26 78 58
Less: Comprehensive income attributable to noncontrolling interests 0 (2) 0 (4)
Comprehensive income attributable to Meritor, Inc. 41 24 78 54
Elims        
Condensed Statement Of Income Captions [Line Items]        
Net income (75) (63) (207) (175)
Other comprehensive income (loss) 38 (16) 73 (10)
Total comprehensive income (37) (79) (134) (185)
Less: Comprehensive income attributable to noncontrolling interests 0 0 0 0
Comprehensive income attributable to Meritor, Inc. $ (37) $ (79) $ (134) $ (185)