Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2016	Sep. 30, 2016
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable	$ 94	$ 92
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	644,694,794	642,796,490
Treasury stock, shares	308,659,218	310,557,522