Leases (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Leases [Abstract]
Leased capital assets included in net property, plant and equipment, primarily buildings and improvements	$ 55	$ 79
Total rental expense	$ 459	$ 470	$ 454