Investments - Summary of Short-term, Long-term Investments and Marketable Securities (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2023	Sep. 30, 2024
Schedule Of Held To Maturity Securities And Marketable Securities [Line Items]
Current investments, Available-for-sale, Adjusted Basis	$ 295,699	$ 577,465
Current investments, Available-for-sale, Gross Unrealized Gains	3	837
Current investments, Available-for-sale, Gross Unrealized Losses	(2,967)	(26)
Current investments, Available-for-sale, Fair Value	292,735	578,276
Marketable debt securities, Adjusted Basis	295,700
Net unrealized loss on held-to-maturity securities	3,000
Debt securities
Schedule Of Held To Maturity Securities And Marketable Securities [Line Items]
Current investments, Available-for-sale, Adjusted Basis	295,699	577,465
Current investments, Available-for-sale, Gross Unrealized Gains	3	837
Current investments, Available-for-sale, Gross Unrealized Losses	(2,967)	(26)
Current investments, Available-for-sale, Fair Value	$ 292,735	$ 578,276

Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, Current

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Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, Current

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Schedule of held to maturity securities and marketable securities.

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481830/320-10-45-2

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

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Amount, before tax and adjustment, of unrealized gain (loss) on investment in debt security measured at amortized cost (held-to-maturity) from transfer to investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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