Long-Term Debt (Details Textuals) (USD $) In Millions, unless otherwise specified		6 Months Ended					6 Months Ended		3 Months Ended	6 Months Ended								3 Months Ended	6 Months Ended
	Mar. 31, 2012	Mar. 31, 2012 Financing Arrangements For Capital Leases [Member]	Mar. 31, 2012 Capital Lease Arrangements [Member]	Mar. 31, 2012 Subsequent Event Revolving Credit Facility [Member]	Jan. 31, 2014 Subsequent Event Revolving Credit Facility [Member]	Dec. 31, 2012 Subsequent Event Revolving Credit Facility [Member]	Mar. 31, 2012 4.625 percent convertible notes due 2026 [Member]	Mar. 31, 2012 4.0 percent convertible notes due 2027 [Member]	Mar. 31, 2012 Revolving Credit Facility [Member]	Mar. 31, 2012 Revolving Credit Facility [Member]	Jan. 31, 2014 Revolving Credit Facility [Member]	Dec. 31, 2011 Revolving Credit Facility [Member]	Sep. 30, 2011 Revolving Credit Facility [Member]	Mar. 31, 2012 Standby Letters Of Credit [Member]	Sep. 30, 2011 Standby Letters Of Credit [Member]	Mar. 31, 2012 Revolving Credit Facility Matures In January 2014 [Member]	Mar. 31, 2012 Revolving Credit Facility Matures In April 2017 [Member]	Mar. 31, 2012 Term Loan [Member]	Mar. 31, 2012 Retirement Of Notes [Member]
Repayments Of Long-Term Debt																			$ 84
Debt Instrument, Convertible, Earliest Date							2016	2019
Line Of Credit Facility, Maximum Borrowing Capacity				429					441	441						14	415	100
Line Of Credit Facility, Expiration Date										January 2014								April 23, 2017
Maximum Limit On The Issuance Of Letters Of Credit									100	100
Letters Of Credit Outstanding, Amount									0	0			0	29	30
Maximum Collateral Test Value									1.0x	1.0x
Required Ratio Of Total Priority Debt To Ebitda Through The Period Ended				2.50 to 1.00	2.00 to 1.00	2.25 to 1.00			2.25 to 1	2.25 to 1	2.00 to 1	2.25 to 1
Actual Ratio Of Total Priority Debt To Ebitda At Period End										0.26x
Value Of Company Assets Collateralized									653	653
Debt Instrument, Description Of Variable Rate Basis		30-day LIBOR plus 575 basis points	564 basis points	425 basis points						LIBOR								425 basis points
Debt Instrument, Basis Spread On Variable Rate									4.25%	4.25%
Line Of Credit Facility, Commitment Fee Description				50 basis points					50	50 basis points
Additional Other Letter Of Credit Outstanding														6	2
Debt Instrument, Interest Rate, Stated Percentage	8.75%						4.625%	4.00%
Description Of Maturity Date Of Debt				The April 2017 maturity date is also subject to the following: if on June 1, 2015, the outstanding principal amount of the company's $250 million bonds due 2015 is greater than $100 million, the maturity date becomes June 10, 2015 and if on November 1, 2015, the outstanding principal amount of the company's $300 million 4.625 percent convertibles notes due 2026 is greater than $100 million and the conversion price of $20.98 is greater than the then current Meritor common stock price, the maturity date becomes November 15, 2015.
Line of Credit Facility, Frequency of Payment and Payment Terms																		5 years
Line Of Credit Facility Periodic Payment Principal During Year One																		5
Line Of Credit Facility Periodic Payment Principal During Remaining Year																		10
Maximum Amount Of Progress Payments For Equipment Under Construction		10
Capital Leases Term			60 months
Capital Lease Obligations, Noncurrent			$ 4
Maximum Collateral Test Values				1.0x