Stock-Based Compensation (Supplemental Stock Option Information) (Details) - Stock Options [Member] - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of options granted at the closing market price of common stock on the grant date	100.00%
Amount of stock option vesting per year	one-third
Stock option expiration years from date of grant years	10 years
Cash received for stock options exercises	$ 114	$ 126	$ 40
Intrinsic value of options exercised	53	47	16
Tax benefit from exercise of stock options	$ 6	$ 8	$ 8