Debt and Financing Arrangements Net Financing Charges (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Debt Disclosure [Abstract]
Interest expense, net of capitalized interest costs	$ 309	$ 288	$ 254
Bank fees and bond cost amortization	34	23	18
Interest income	(14)	(9)	(10)
Net foreign exchange results for financing activities	(15)	(14)	(18)
Net financing charges	$ 314	$ 288	$ 244