Pension, Postretirement and Other Benefits - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009
Defined Benefit Plan Disclosure [Line Items]
Cash balance formula contributions, rate of eligible compensation	6.00%
Decrease in net periodic pension cost due to amendment to the U.S. pension plan	$ 19
Assumed annual rate of future increases in health benefits for the other postretirement benefits plan for fiscal 2012	8.00%
Assumed annual rate of future decreases in health benefits for the other postretirement benefits plan by 2019	5.00%
Increasing or decreasing the healthcare cost trend by one percent would increase decrease the postretirement accumulated plan benefit obligation by less than	1
Target allocation for plan assets, equity securities, minimum	50.00%
Target allocation for plan assets, equity securities, maximum	80.00%
Target allocation for plan assets, fixed income securities, minimum	25.00%
Target allocation for plan assets, fixed income securities, maximum	35.00%
Target allocation for plan assets, other	7.00%
Plan asset allocation, equity securities	60.00%
Plan asset allocation, fixed income securities	33.00%
Plan asset allocation, other	7.00%
Defined contribution plan, personnel costs	$ 34	$ 29	$ 28