CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 92	$ (34)
Foreign currency translation adjustments:
Attributable to Meritor, Inc.	(4)	(8)
Attributable to noncontrolling interest	1	1
Pension and other postretirement benefit related adjustments	0	3
Unrealized gain on investments and foreign exchange contracts	1	0
Other comprehensive loss, net of tax	(2)	(4)
Total comprehensive income (loss)	90	(38)
Less: Comprehensive income attributable to noncontrolling interest	(3)	(3)
Comprehensive income (loss) attributable to Meritor, Inc.	$ 87	$ (41)