Stock-Based Compensation - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Mar. 18, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized (in shares)	6,186,644		6,186,644
Granted (in shares)			32,151
Stock-based compensation expense	$ 19,947	$ 33,390	$ 59,949	$ 91,697
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Intrinsic value of options exercised	6,500	1,600	10,100	24,900
Stock-based compensation expense	2,100	2,600	6,700	8,300
Unrecognized pre-tax compensation expense	5,300		$ 5,300
Weighted average period to recognize pre-tax compensation expense			12 months
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	17,800	$ 33,700	$ 53,200	$ 83,400
Weighted average period to recognize pre-tax compensation expense			2 years 3 months 18 days
Unrecognized pre-tax compensation expense	$ 131,600		$ 131,600
2004 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserve for issuance (in shares)	68,555		68,555
2013 Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserve for issuance (in shares)	3,440,076		3,440,076
Number of shares forfeited (in shares)			197,596
2021 Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized (in shares)					8,000,000
Granted (in shares)			1,977,114
Inducement Awards | Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserve for issuance (in shares)	712,454		712,454
Inducement Awards | Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserve for issuance (in shares)	746,175		746,175