Stock-Based Compensation - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Oct. 01, 2023	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Sep. 30, 2024	Sep. 30, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Granted (in shares)				0
Common stock, share reserve for issuance (in shares)		2,308,495		2,308,495
Number of options outstanding (in shares)		1,484,623		1,484,623		1,978,516
Stock-based compensation expense		$ 11,993	$ 14,711	$ 41,250	$ 48,984
Restricted stock units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award (in shares)		5,980,922		5,980,922		4,913,312
Stock-based compensation expense		$ 11,900	14,300	$ 41,100	46,500
Unrecognized pre-tax compensation expense		85,800		$ 85,800
Weighted average period to recognize pre-tax compensation expense				1 year 8 months 12 days
Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Intrinsic value of options exercised		300	700	$ 4,900	3,800
Stock-based compensation expense		$ 0	400	$ 100	2,500
2013 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserve for issuance (in shares)		2,350,117		2,350,117
Number of shares forfeited (in shares)				170,898
Number of options outstanding (in shares)		850,117		850,117
2013 Plan | Restricted stock units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award (in shares)		1,500,000		1,500,000
2021 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized (in shares)							8,000,000
Granted (in shares)				6,215,559
Number of shares forfeited (in shares)				353,156
Number of options outstanding (in shares)		32,151		32,151
2021 Plan | Restricted stock units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award (in shares)		3,888,660		3,888,660
Inducement Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized (in shares)		832,950		832,950
Granted (in shares)				607,340
Common stock, share reserve for issuance (in shares)		307,924		307,924
Number of options outstanding (in shares)		602,355		602,355
Inducement Awards | Restricted stock units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award (in shares)		138,775		138,775
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		$ 1,100	$ 2,300	$ 3,000	$ 5,500