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	$ 295	$ 288	$ 254
Bank fees and bond cost amortization	32	23	18
Interest income	(12)	(9)	(10)
Net foreign exchange results for financing activities	(15)	(14)	(18)
Net financing charges	300	288	244
Interest expense due to affiliate	$ 27	$ 0	$ 0