v3.26.1
Fair Value of Financial Assets and Liabilities - Financial Assets and Liabilities that were Subject to Fair Value Measurement on Recurring Basis (Detail) - USD ($)
$ in Thousands
Jun. 30, 2026
Sep. 30, 2025
Assets:    
Marketable securities $ 178,074 $ 156,566
Assets, Fair Value Disclosure, Total 203,606 168,146
Liabilities:    
Liabilities, Fair Value Disclosure, Total 1,311 1,311
Series 1 Nonconvertible Preferred Stock [Member]    
Liabilities:    
Liabilities 1,311 1,311
Level 1 [Member]    
Assets:    
Assets, Fair Value Disclosure, Total 203,606 168,146
Liabilities:    
Liabilities, Fair Value Disclosure, Total 0 0
Level 1 [Member] | Series 1 Nonconvertible Preferred Stock [Member]    
Liabilities:    
Liabilities 0 0
Level 2 [Member]    
Assets:    
Assets, Fair Value Disclosure, Total 0 0
Liabilities:    
Liabilities, Fair Value Disclosure, Total 0 0
Level 2 [Member] | Series 1 Nonconvertible Preferred Stock [Member]    
Liabilities:    
Liabilities 0 0
Level 3 [Member]    
Assets:    
Assets, Fair Value Disclosure, Total 0 0
Liabilities:    
Liabilities, Fair Value Disclosure, Total 1,311 1,311
Level 3 [Member] | Series 1 Nonconvertible Preferred Stock [Member]    
Liabilities:    
Liabilities 1,311 1,311
Money Market Funds [Member]    
Assets:    
Cash equivalents 25,532 11,580
Money Market Funds [Member] | Level 1 [Member]    
Assets:    
Cash equivalents 25,532 11,580
Money Market Funds [Member] | Level 2 [Member]    
Assets:    
Cash equivalents 0 0
Money Market Funds [Member] | Level 3 [Member]    
Assets:    
Cash equivalents 0 0
U.S. Treasury Notes [Member]    
Assets:    
Marketable securities 178,074 156,566
U.S. Treasury Notes [Member] | Level 1 [Member]    
Assets:    
Marketable securities 178,074 156,566
U.S. Treasury Notes [Member] | Level 2 [Member]    
Assets:    
Marketable securities 0 0
U.S. Treasury Notes [Member] | Level 3 [Member]    
Assets:    
Marketable securities $ 0 $ 0