Debt and Financing Arrangements - Components of Net Financing Charges (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Debt Disclosure [Abstract]
Interest expense, net of capitalized interest costs	$ 69	$ 72	$ 142	$ 143
Banking fees and bond cost amortization	5	6	13	12
Interest income	(3)	(1)	(5)	(4)
Net foreign exchange results for financing activities	3	(8)	(8)	(11)
Net financing charges	$ 74	$ 69	$ 142	$ 140