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)