Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2015	Sep. 30, 2014
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable	$ 103	$ 114
Common stock, par value per share	$ 0.50	$ 0.50
Common stock, shares authorized	1,200,000,000	1,200,000,000
Common stock, shares issued	953,354,012	953,354,012
Common stock, shares outstanding	663,311,878	696,605,222
Treasury stock, shares	290,042,134	256,748,790