XML 30 R15.htm IDEA: XBRL DOCUMENT
v3.23.3

Marketable Securities | 12 Months Ended
--- | ---
Sep. 30, 2023
Investments, Debt and Equity Securities [Abstract] |
Marketable Securities | 5. Marketable Securities During fiscal years 2023 and 2022, the Company had sales and maturities of marketable securities of $1.1 billion and $705.4 million, respectively. Realized losses on the sale of marketable securities were $0.8 million for the fiscal year ended September 30, 2023, and realized gains on the sale of marketable securities were $0.2 million for the fiscal year ended September 30, 2022. The following is a summary of the amortized cost and the fair value, including accrued interest receivable, as well as unrealized gains (losses) on the short-term and long-term marketable securities as of September 30, 2023 and 2022 (in thousands):
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ |  | ​ |  | Gross |  | Gross |  | ​
​ | ​ | Amortized | ​ | Unrealized | ​ | Unrealized | ​ | ​
​ | ​ | Cost | ​ | Losses | ​ | Gains | ​ | Fair Value
September 30, 2023: |  | ​ |  |  | ​ |  |  | ​ |  |  | ​ |
U.S. Treasury securities and obligations of U.S. government agencies |  | $ | 227,804 | ​ | $ | (2,573) | ​ | $ | — |  | $ | 225,231
Bank certificates of deposits | ​ | ​ | 8,122 | ​ | ​ | (170) | ​ | ​ | — | ​ | ​ | 7,952
Corporate securities | ​ | ​ | 221,155 | ​ | ​ | (4,127) | ​ | ​ | — | ​ | ​ | 217,028
Municipal securities |  | ​ | — | ​ | ​ | — | ​ | ​ | — |  | ​ | —
​ | ​ | $ | 457,081 | ​ | $ | (6,870) | ​ | $ | — | ​ | $ | 450,211
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
​ ​ The fair values of the marketable securities by contractual maturities at September 30, 2023 are presented below (in thousands). ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Amortized | ​ | ​ | ​
​ | ​ | Cost | ​ | ​ | Fair Value
Due in one year or less | ​ | $ | 342,901 | ​ | $ | 338,873
Due after one year through five years | ​ |  | 111,121 | ​ |  | 108,279
Due after five years through ten years | ​ | ​ | — | ​ | ​ | —
Due after ten years | ​ |  | 3,059 | ​ |  | 3,059
Total marketable securities | ​ | $ | 457,081 | ​ | $ | 450,211
​ Expected maturities could differ from contractual maturities because the security issuers may have the right to prepay obligations without prepayment penalties. Unrealized losses from fixed-income securities are primarily attributable to changes in interest rates. Management does not believe any unrealized losses represent impairments based on our evaluation of the available evidence.

X
- References No definition available. + Details
Name: | us-gaap_InvestmentsDebtAndEquitySecuritiesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The entire disclosure for investments in certain debt and equity securities. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -Name Accounting Standards Codification -Publisher FASB -URI https://asc.fasb.org//320/tableOfContent Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 10 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-10 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6B -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-6B Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6B -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-6B Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Name Regulation S-K (SK) -Number 229 -Section 1403 -Paragraph (b) -Publisher SEC Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 946 -SubTopic 320 -Name Accounting Standards Codification -Publisher FASB -URI https://asc.fasb.org//946-320/tableOfContent Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 940 -SubTopic 320 -Name Accounting Standards Codification -Publisher FASB -URI https://asc.fasb.org//940-320/tableOfContent Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 320 -Name Accounting Standards Codification -Publisher FASB -URI https://asc.fasb.org//942-320/tableOfContent + Details
Name: | us-gaap_InvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration