Stock-Based Compensation - Schedule of Cash Proceeds Received and Tax Benefit from Share-based Payment Awards, Options (Details) - Employee Stock Option - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash received for option exercises	$ 49	$ 15	$ 114
Intrinsic value of options exercised	27	11	53
Tax benefits related to option exercises	$ 4	$ 7	$ 6