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v3.23.2

Marketable Securities (Tables) | 9 Months Ended
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Jun. 30, 2023
Investments, Debt and Equity Securities [Abstract] |
Summary of Amortized Cost and Fair Value, Including Accrued Interest Receivable and Unrealized Holding Gains (Losses) on Short-term and Long-term Marketable Securities | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ |  | ​ |  | Gross |  | Gross |  | ​
​ | ​ | Amortized | ​ | Unrealized | ​ | Unrealized | ​ | ​
​ | ​ | Cost | ​ | Losses | ​ | Gains | ​ | Fair Value
June 30, 2023: |  | ​ |  |  | ​ |  |  | ​ |  |  | ​ |
U.S. Treasury securities and obligations of U.S. government agencies |  | $ | 311,618 | ​ | $ | (3,731) | ​ | $ | 1 |  | $ | 307,888
Bank certificates of deposits | ​ | ​ | 9,078 | ​ | ​ | (194) | ​ | ​ | — | ​ | ​ | 8,884
Corporate securities | ​ | ​ | 248,309 | ​ | ​ | (5,186) | ​ | ​ | — | ​ | ​ | 243,123
Municipal securities |  | ​ | 20 | ​ | ​ | (1) | ​ | ​ | — |  | ​ | 19
​ | ​ | $ | 569,025 | ​ | $ | (9,112) | ​ | $ | 1 | ​ | $ | 559,914
September 30, 2022: | ​ | ​ |  | ​ |  |  | ​ |  |  | ​ |  |
U.S. Treasury securities and obligations of U.S. government agencies | ​ | $ | 804,774 |  | $ | (6,163) |  | $ | 21 | ​ | $ | 798,632
Bank certificates of deposits | ​ | ​ | 8,335 | ​ | ​ | (158) | ​ | ​ | 1 | ​ | ​ | 8,178
Corporate securities | ​ | ​ | 406,270 | ​ | ​ | (8,113) | ​ | ​ | — | ​ | ​ | 398,157
Municipal securities | ​ |  | 59,043 | ​ | ​ | (226) | ​ | ​ | — |  | ​ | 58,817
​ | ​ | $ | 1,278,422 | ​ | $ | (14,660) | ​ | $ | 22 | ​ | $ | 1,263,784
Fair Value of Marketable Securities by Contractual Maturity | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Amortized | ​ | ​ | ​
​ | ​ | Cost | ​ | ​ | Fair Value
Due in one year or less | ​ | $ | 394,811 | ​ | $ | 390,492
Due after one year through five years | ​ |  | 171,049 | ​ |  | 166,257
Due after five years through ten years | ​ | ​ | — | ​ | ​ | —
Due after ten years | ​ |  | 3,165 | ​ |  | 3,165
Total marketable securities | ​ | $ | 569,025 | ​ | $ | 559,914

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- Definition Tabular disclosure of maturities of an entity's investments as well as any other information pertinent to the investments. + References No definition available. + Details
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- Definition Tabular disclosure of the reconciliation of available-for-sale securities from cost basis to fair value. + References No definition available. + Details
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