Capital Stock (Common Stock Narrative) (Details) - USD ($)	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015	Sep. 15, 2011
Equity [Abstract]
Common stock, authorized shares	300,000,000
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares issued	249,455,584	249,455,584
Common stock, shares outstanding	219,515,245	218,346,074	217,350,825	215,359,113
Share repurchase program authorized amount					$ 1,000,000,000.0
Shares repurchased during period (shares)	0
Share repurchase authorization remaining amount	$ 485,300,000