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Fair Value Assets - Measured on a Recurring Basis (Details) - USD ($) $ in Thousands | Sep. 30, 2022 | Sep. 30, 2021
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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

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- Definition 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. + References No definition available. + Details
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