Shareowners' Equity - Common Stock (Details) - USD ($)	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Shareowners' Equity (Textuals) [Abstract]
Common stock, authorized (in shares)	1,000,000,000
Common stock, par value (in dollars per share)	$ 1	$ 1.00
Preferred stock, authorized (in shares)	25,000,000
Common stock reserved for various incentive plans	9,600,000.0
Outstanding purchase of common stock recorded in accounts payable	$ 18,300,000	$ 0
Changes in outstanding common shares
Beginning balance (in shares)	128,400,000	128,500,000	132,400,000
Treasury stock purchases (in shares)	(8,300,000)	(2,300,000)	(4,600,000)
Shares delivered under incentive plans (in shares)	900,000	2,200,000	700,000
Ending balance (in shares)	121,000,000	128,400,000	128,500,000