Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2017	Sep. 30, 2016
Allowance for doubtful accounts receivables	$ 91	$ 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	641,691,971	642,796,490
Treasury stock, shares	311,662,041	310,557,522