Stock-Based Compensation - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Oct. 01, 2023	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023	Mar. 18, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, share reserve for issuance (in shares)		4,553,827		4,553,827
Granted (in shares)				0	0
Stock-based compensation expense		$ 16,588	$ 20,613	$ 34,273	$ 40,002
Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Intrinsic value of options exercised		2,500	1,400	3,100	3,600
Stock-based compensation expense		600	2,200	2,100	4,600
Unrecognized pre-tax compensation expense		800		$ 800
Weighted average period to recognize pre-tax compensation expense				4 months
Restricted stock units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense		16,000	$ 18,400	$ 32,200	$ 35,400
Weighted average period to recognize pre-tax compensation expense				1 year 8 months 12 days
Unrecognized pre-tax compensation expense		$ 112,000		$ 112,000
2004 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserve for issuance (in shares)		0		0
2013 Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserve for issuance (in shares)		2,967,887		2,967,887
Number of shares forfeited (in shares)				158,678
2021 Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized (in shares)						8,000,000
Number of shares forfeited (in shares)				134,389
Granted (in shares)				3,689,089
Inducement Awards | Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserve for issuance (in shares)		688,165		688,165
Inducement Awards | Restricted stock units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserve for issuance (in shares)		637,563		637,563
Visirna ESOP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized (in shares)	20,000,000
Granted (in shares)	7,500,000
Stock-based compensation expense		$ 1,200		$ 3,200