Leases (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Leases [Abstract]
Leased capital assets included in net property, plant and equipment, primarily buildings and improvements	$ 79	$ 96
Total rental expense	$ 470	$ 454	$ 424