Fair Value Measurements - Summary of Net Gains and Losses on Total Return Derivatives (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Total Return Derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total return swap gain (loss)	$ 0	$ 0	$ 0	$ 0