v3.25.2
Marketable Securities and Fair Value Measurements - Company's Assets Measured at Fair Value (Detail) - USD ($)
Mar. 31, 2025
Sep. 30, 2024
Summary of Investment Holdings [Line Items]    
Total $ 91,405,000 $ 89,927,000
Level 1 [Member]    
Summary of Investment Holdings [Line Items]    
Total 59,643,000 55,633,000
Level 2 [Member]    
Summary of Investment Holdings [Line Items]    
Total 31,762,000 34,294,000
Exchange Traded Funds [Member]    
Summary of Investment Holdings [Line Items]    
Total 5,591,000 3,686,000
Exchange Traded Funds [Member] | Level 1 [Member]    
Summary of Investment Holdings [Line Items]    
Total 5,591,000 3,686,000
Mutual Funds [Member]    
Summary of Investment Holdings [Line Items]    
Total 1,015,000  
Mutual Funds [Member] | Level 1 [Member]    
Summary of Investment Holdings [Line Items]    
Total 1,015,000  
Corporate Bonds [Member]    
Summary of Investment Holdings [Line Items]    
Total 31,762,000 34,294,000
Corporate Bonds [Member] | Level 2 [Member]    
Summary of Investment Holdings [Line Items]    
Total 31,762,000 34,294,000
Government Securities [Member]    
Summary of Investment Holdings [Line Items]    
Total 52,821,000 50,111,000
Government Securities [Member] | Level 1 [Member]    
Summary of Investment Holdings [Line Items]    
Total 52,821,000 50,111,000
Cash and Money Funds [Member]    
Summary of Investment Holdings [Line Items]    
Total 216,000 1,836,000
Cash and Money Funds [Member] | Level 1 [Member]    
Summary of Investment Holdings [Line Items]    
Total $ 216,000 $ 1,836,000