Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Allowance for doubtful accounts receivables	$ 138	$ 112
Common stock, par value per share	$ 0.50	$ 0.50
Common stock, shares authorized	1,200,000	1,200,000
Common stock, shares issued	953,400	953,400
Common stock, shares outstanding	598,000	611,000
Treasury stock, shares	355,400	342,400