Summary of Significant Accounting Policies - Schedule of Cash and Restricted Cash (Details) - USD ($) $ in Millions	Jun. 30, 2024	Sep. 30, 2023	Jun. 30, 2023	Sep. 30, 2022
Accounting Policies [Abstract]
Cash and cash equivalents	$ 183	$ 241	$ 260
Restricted cash	28	99	78
Cash, cash equivalents and restricted cash	$ 211	$ 340	$ 338	$ 469