Income Taxes - Summary of Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowance, beginning of year	$ 52,085	$ 205,423	$ 177,663
Net release of valuation allowance	0	(134,235)	0
Net increase (decrease) in deferred tax assets with a full valuation allowance	(29,802)	(19,103)	27,760
Valuation allowance, end of year	$ 22,283	$ 52,085	$ 205,423