Investments - Summary of Short-term, Long-term Investments and Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021
Schedule Of Held To Maturity Securities And Marketable Securities [Line Items]
Short-term investments, Held to maturity, Adjusted Bases	$ 268,391	$ 56,627
Short-term investments, Held to maturity, Gross Unrealized Gains	0	803
Short-term investments, Held to maturity, Gross Unrealized Losses	(3,661)	0
Short-term investments, Held to maturity, Fair Value	264,730	57,430
Long-term investments, Held to maturity, Adjusted Basis	105,872	245,595
Long-term investments, Held to maturity, Gross Unrealized Gains	0	1,151
Long-term investments, Held to maturity, Gross Unrealized Losses	(5,569)	(103)
Long-term investments, Held to maturity, Fair Value	100,303	246,643
Marketable debt securities, Adjusted Basis	0	127,481
Marketable debt securities, Gross Unrealized Gains	0	0
Marketable debt securities, Gross Unrealized Losses	0	(753)
Marketable debt securities, Fair Value	0	126,728
Debt securities
Schedule Of Held To Maturity Securities And Marketable Securities [Line Items]
Short-term investments, Held to maturity, Adjusted Bases	218,391	56,627
Short-term investments, Held to maturity, Gross Unrealized Gains	0	803
Short-term investments, Held to maturity, Gross Unrealized Losses	(3,661)	0
Short-term investments, Held to maturity, Fair Value	214,730	57,430
Long-term investments, Held to maturity, Adjusted Basis	105,872	195,595
Long-term investments, Held to maturity, Gross Unrealized Gains	0	1,151
Long-term investments, Held to maturity, Gross Unrealized Losses	(5,569)	(103)
Long-term investments, Held to maturity, Fair Value	100,303	196,643
Certificate of deposits
Schedule Of Held To Maturity Securities And Marketable Securities [Line Items]
Short-term investments, Held to maturity, Adjusted Bases	50,000
Short-term investments, Held to maturity, Gross Unrealized Gains	0
Short-term investments, Held to maturity, Gross Unrealized Losses	0
Short-term investments, Held to maturity, Fair Value	$ 50,000
Long-term investments, Held to maturity, Adjusted Basis		50,000
Long-term investments, Held to maturity, Gross Unrealized Gains		0
Long-term investments, Held to maturity, Gross Unrealized Losses		0
Long-term investments, Held to maturity, Fair Value		$ 50,000

Debt Securities, Held-to-Maturity, Accumulated Unrecognized Gain, Current

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