Shareowners' Equity - Common Stock (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Shareowners' Equity (Textuals) [Abstract]
Common stock, authorized (in shares)	1,000,000,000,000,000,000
Common stock, par value (in dollars per share)	$ 1.00	$ 1
Preferred stock, authorized (in shares)	25,000,000
Common stock reserved for various incentive plans (in shares)	8,700,000
Outstanding purchase of common stock recorded in accounts payable	$ 9.3	$ 18.3
Changes in outstanding common shares
Beginning balance (in shares)	121,000,000.0	128,400,000	128,500,000
Treasury stock purchases (in shares)	(6,100,000)	(8,300,000)	(2,300,000)
Shares delivered under incentive plans (in shares)	800,000	900,000	2,200,000
Ending balance (in shares)	115,700,000	121,000,000.0	128,400,000