Stock-Based Compensation - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended			24 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2025	Sep. 30, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards granted and outstanding (in shares)	7,217,386			7,217,386
Granted (in shares)	0	0	0
Common stock reserved for issuance (in shares)	2,378,770			2,378,770
Number of options outstanding (in shares)	1,407,035	1,978,516		1,407,035
Stock compensation	$ 54,848	$ 67,097	$ 78,130
Restricted stock units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award (in shares)	5,810,351	4,913,312		5,810,351
Stock compensation	$ 54,900	$ 64,300	69,700
Unrecognized pre-tax compensation expense	$ 73,300			$ 73,300
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	$ 6,400	4,200	12,200
Stock compensation	$ 100	2,800	$ 8,400
2013 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards granted and outstanding (in shares)	2,276,279			2,276,279
Number of shares forfeited (in shares)	170,898
Number of options outstanding (in shares)	776,279			776,279
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]
Awards granted and outstanding (in shares)	3,782,222			3,782,222
Number of shares authorized (in shares)					8,000,000
Granted (in shares)	6,231,559
Number of shares forfeited (in shares)	439,431
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)	3,750,071			3,750,071
Inducement Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized (in shares)	832,950			832,950
Granted (in shares)	660,020
Common stock reserved for issuance (in shares)	255,244			255,244
Number of options outstanding (in shares)	598,605			598,605
Inducement Plan | Restricted stock units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based payment award (in shares)	53,713			53,713
Visirna ESOP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized (in shares)	20,000,000			20,000,000
Granted (in shares)				14,612,000
Stock compensation	$ 8,500	$ 6,900