Weighted Average Common Shares (Details) - shares shares in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Antidilutive shares excluded from computation of diluted earnings per share	13.3	5.9	4.6
Basic shares outstanding	644.0	673.3	700.2
Dilutive shares	2.8	3.2	3.9
Diluted shares outstanding	646.8	676.5	704.1