Other Financial Data (Other Operating Cash Flow) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Disclosure Text Block [Abstract]
Pension expense	$ 127	$ 95	$ 153
Stock compensation expense	110	145	24
Deferred income taxes and other	27	45	19
Total	$ 264	$ 285	$ 196