CONDENSED CONSOLIDATED STATEMENT OF EQUITY (DEFICIT) (Unaudited) (USD $) In Millions, unless otherwise specified	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Treasury Stock	Accumulated Other Comprehensive Loss	Total Deficit Attributable to Meritor, Inc.	Noncontrolling Interests
Beginning balance at Sep. 30, 2013	$ (822)	$ 97	$ 914	$ (1,127)	$ 0	$ (734)	$ (850)	$ 28
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	38			12		22	34	4
Equity based compensation expense	3		3				3
Noncontrolling interest dividends	(1)							(1)
Ending Balance at Mar. 31, 2014	(782)	97	917	(1,115)	0	(712)	(813)	31
Beginning balance at Sep. 30, 2014	(585)	97	918	(878)	0	(749)	(612)	27
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	28			72		(44)	28	0
Equity based compensation expense	5		5				5
Vesting of restricted stock	0	2	(2)
Repurchase of convertible notes	(2)		(2)				(2)
Repurchase of common stock	(16)				(16)		(16)
Noncontrolling interest dividends	(1)							(1)
Other equity adjustments	1		1				1
Ending Balance at Mar. 31, 2015	$ (570)	$ 99	$ 920	$ (806)	$ (16)	$ (793)	$ (596)	$ 26