Investments (Tables)

6 Months Ended

Mar. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Summary of Short-term and Long-term Investments and Marketable Securities

The Company’s investments consisted of the following:

	As of March 31, 2023
	(In thousands)
	Adjusted Basis		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Short-term investments (due within one year)
Held to maturity debt securities	$	346,046	$	—	$	(3,755)	$	342,291
Held to maturity certificate of deposit	—		—		—		—
Total short-term investments	$	346,046	$	—	$	(3,755)	$	342,291
Long-term investments (due within one through three years)
Held to maturity debt securities	$	78,834	$	—	$	(1,709)	$	77,125
Total long-term investments	$	78,834	$	—	$	(1,709)	$	77,125

	As of September 30, 2022
	(In thousands)
	Adjusted Basis		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Short-term investments (due within one year)
Held to maturity debt securities	$	218,391	$	—	$	(3,661)	$	214,730
Held to maturity certificate of deposit	50,000		—		—		50,000
Total short-term investments	$	268,391	$	—	$	(3,661)	$	264,730
Long-term investments (due within one through three years)
Held to maturity debt securities	$	105,872	$	—	$	(5,569)	$	100,303
Total long-term investments	$	105,872	$	—	$	(5,569)	$	100,303