v3.26.1
Marketable Securities - Reconciliation of Marketable Securities (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Sep. 30, 2025
Amortized Cost $ 324,991 $ 262,578
Gross Unrealized Losses (745) (94)
Gross Unrealized Gains 69 238
Fair Value 324,315 262,722
U.S. Treasury securities and obligations of U.S. government agencies    
Amortized Cost 240,421 245,691
Gross Unrealized Losses (420) (94)
Gross Unrealized Gains 22 168
Fair Value 240,023 245,765
Bank certificates of deposit    
Amortized Cost 1,285 1,640
Gross Unrealized Losses 0 0
Gross Unrealized Gains 0 1
Fair Value 1,285 1,641
Corporate securities    
Amortized Cost 68,610 4,199
Gross Unrealized Losses (325) 0
Gross Unrealized Gains 3 0
Fair Value 68,288 4,199
Municipal securities    
Amortized Cost 14,675 11,048
Gross Unrealized Losses 0 0
Gross Unrealized Gains 44 69
Fair Value $ 14,719 $ 11,117