Marketable Securities - Reconciliation of Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Sep. 30, 2025
Amortized Cost	$ 333,570	$ 262,578
Gross Unrealized Losses	(1,350)	(94)
Gross Unrealized Gains	10	238
Fair Value	332,230	262,722
U.S. Treasury securities and obligations of U.S. government agencies
Amortized Cost	244,688	245,691
Gross Unrealized Losses	(853)	(94)
Gross Unrealized Gains	2	168
Fair Value	243,837	245,765
Bank certificates of deposit
Amortized Cost	1,253	1,640
Gross Unrealized Losses	(1)	0
Gross Unrealized Gains	0	1
Fair Value	1,252	1,641
Corporate securities
Amortized Cost	72,907	4,199
Gross Unrealized Losses	(468)	0
Gross Unrealized Gains	0	0
Fair Value	72,439	4,199
Municipal securities
Amortized Cost	14,722	11,048
Gross Unrealized Losses	(28)	0
Gross Unrealized Gains	8	69
Fair Value	$ 14,702	$ 11,117

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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+ Details