Marketable Securities (Tables)

3 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Summary of amortized cost and fair value

			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Losses		Gains		Fair Value
December 31, 2023:
U.S. Treasury securities and obligations of U.S. government agencies	$	148,119	$	(1,200)	$	—	$	146,919
Bank certificates of deposit		7,842		(94)		—		7,748
Corporate securities		190,696		(2,189)		—		188,507
	$	346,657	$	(3,483)	$	—	$	343,174
September 30, 2023:
U.S. Treasury securities and obligations of U.S. government agencies	$	227,804	$	(2,573)	$	—	$	225,231
Bank certificates of deposit		8,122		(170)		—		7,952
Corporate securities		221,155		(4,127)		—		217,028
	$	457,081	$	(6,870)	$	—	$	450,211

Schedule of fair values of marketable securities by contractual maturities

	Amortized
	Cost			Fair Value
Due in one year or less	$	283,849	$	281,212
Due after one year through five years		59,486		58,640
Due after five years through ten years		—		—
Due after ten years		3,322		3,322
Total marketable securities	$	346,657	$	343,174