Summary of Significant Accounting Policies - Schedule of Cash and Restricted Cash (Details) - USD ($) $ in Millions	Mar. 31, 2023	Sep. 30, 2022	Mar. 31, 2022	Sep. 30, 2021
Accounting Policies [Abstract]
Cash and cash equivalents	$ 321	$ 405	$ 718
Restricted cash	82	64	55
Cash, cash equivalents and restricted cash	$ 403	$ 469	$ 773	$ 877