Marketable Securities (Tables)

12 Months Ended

Sep. 30, 2022

Investments, Debt and Equity Securities [Abstract]

Fair Value of Available-for-Sale Marketable Securities by Type of Security

As of September 30, 2022 and 2021, the fair value of available-for-sale marketable securities, by type of security, was as follows:

	September 30, 2022
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Credit Losses		Fair Value
	(in thousands)
Corporate bonds	$	78,663	$	—	$	(2,252	)	$	—	$	76,411
Commercial paper		66,784		—		—			—		66,784
U.S. Treasury notes		92,416		—		(1,088	)		—		91,328
	$	237,863	$	—	$	(3,340	)	$	—	$	234,523

	September 30, 2021
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Credit Losses		Fair Value
	(in thousands)
Corporate bonds	$	124,678	$	93	$	(68	)	$	—	$	124,703
Commercial paper		87,471		—		—			—		87,471
U.S. Treasury notes		83,061		3		(26	)		—		83,038
	$	295,210	$	96	$	(94	)	$	—	$	295,212