Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018
Statement Of Financial Position [Abstract]
Accounts and notes receivable, reserve for doubtful accounts	$ 3	$ 7
Preferred stock, authorized shares	2,000,000	2,000,000
Preferred stock, par value	$ 1	$ 1
Preferred stock, Issued shares	0	0
Preferred stock, Outstanding shares	0	0
Common stock, authorized shares	200,000,000	200,000,000
Common stock, par value	$ 1	$ 1
Common stock, issued shares	57,250,454	60,566,375
Common stock, outstanding shares	57,080,589	60,366,569
Common treasury stock, shares	169,865	199,806