Fair Value Assets - Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents, fair value	$ 287,932	$ 21,547
Debt Securities, Available-for-sale, Amortized Cost	422,699	483,931
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax	0	145
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax	(1,787)	(121)
Debt Securities, Available-for-Sale	420,912	483,955
Debt Securities, Available-for-sale, Current	126,554	329,630
Debt Securities, Available-for-sale, Noncurrent	6,426	132,778
Equity Securities, FV-NI	3,118
Equity Securities, FV-NI, Current	0
Equity Securities, FV-NI, Noncurrent	3,118
Investments, Fair Value Disclosure	424,030
Short-term investments	126,554	329,630
Long-term investments	9,544	132,778
Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents, fair value	276,294	17,150
Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Amortized Cost		255
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax		0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax		0
Corporate Bonds And Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	50,828	243,568
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax	0	129
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax	(950)	(86)
Municipal Bonds And Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	5,018	24,684
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax	0	2
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax	(102)	(9)
US Government Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	84,734	162,221
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax	0	14
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax	(660)	(12)
US Government Agencies Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	5,825	36,053
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax	(75)	(14)
Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities, FV-NI	3,118
Equity Securities, FV-NI, Current	0
Equity Securities, FV-NI, Noncurrent	3,118
Fair Value, Recurring [Member] \| Level 1 \| Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents, fair value	276,294	17,150
Fair Value, Recurring [Member] \| Level 2 \| Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale		255
Debt Securities, Available-for-sale, Current		255
Debt Securities, Available-for-sale, Noncurrent		0
Fair Value, Recurring [Member] \| Level 2 \| Corporate Bonds And Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents, fair value	912	4,397
Debt Securities, Available-for-Sale	49,878	243,611
Debt Securities, Available-for-sale, Current	44,356	186,107
Debt Securities, Available-for-sale, Noncurrent	4,610	53,107
Fair Value, Recurring [Member] \| Level 2 \| Municipal Bonds And Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-Sale	4,916	24,677
Debt Securities, Available-for-sale, Current	3,812	13,566
Debt Securities, Available-for-sale, Noncurrent	1,104	11,111
Fair Value, Recurring [Member] \| Level 2 \| US Government Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents, fair value	10,120
Debt Securities, Available-for-Sale	84,074	162,223
Debt Securities, Available-for-sale, Current	73,954	102,615
Debt Securities, Available-for-sale, Noncurrent	0	59,608
Fair Value, Recurring [Member] \| Level 2 \| US Government Agencies Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents, fair value	606
Debt Securities, Available-for-Sale	5,750	36,039
Debt Securities, Available-for-sale, Current	4,432	27,087
Debt Securities, Available-for-sale, Noncurrent	$ 712	$ 8,952

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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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).

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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).

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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.

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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 noncurrent.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as noncurrent.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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The total amount of investments that are intended to be held for an extended period of time (longer than one operating cycle).

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Amount of investments including trading securities, available-for-sale securities, held-to-maturity securities, and short-term investments classified as other and current.

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