| Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis |
The following tables summarize our financial assets and liabilities measured at fair value and indicate the level in the fair value hierarchy in which we classify the fair value measurement as of the dates indicated below: | | | | | | | | | | | | | | | | | | | | | | | | | December 31, 2024 | | (in thousands) | Fair Value | | Level 1 | | Level 2 | | Level 3 | | Assets | | | | | | | | | Short-term investments: | | | | | | | | | Money market mutual funds | $ | 72,305 | | | $ | 72,305 | | | $ | — | | | $ | — | | | Corporate and municipal debt securities | 26,234 | | | — | | | 26,234 | | | — | | | U.S. government and federal agency securities | 36,778 | | | 36,778 | | | — | | | — | | | Total | 135,317 | | | 109,083 | | | 26,234 | | | — | | | | | | | | | | | Long-term Investments: | | | | | | | | | Recurring fair value measurements: | | | | | | | | | Equity securities: | | | | | | | | | Non-qualified supplemental savings plan | 16,275 | | | 16,275 | | | — | | | — | | | Investment in Tamboran | 19,810 | | | 19,810 | | | — | | | — | | | Debt securities: | | | | | | | | | Investment in Galileo, net | 27,499 | | | — | | | — | | | 27,499 | | | Geothermal debt securities, net | 2,000 | | | — | | | — | | | 2,000 | | | Other debt securities | 4,988 | | | 4,738 | | | — | | | 250 | | | Total | 70,572 | | | 40,823 | | | — | | | 29,749 | |
| | | | | | | | | | | | | | | | | | | | | | | | | September 30, 2024 | | (in thousands) | Fair Value | | Level 1 | | Level 2 | | Level 3 | | Assets | | | | | | | | | Short-term investments: | | | | | | | | | Corporate debt securities | $ | 33,813 | | | $ | — | | | $ | 33,813 | | | $ | — | | | U.S. government and federal agency securities | 53,490 | | | 53,490 | | | — | | | — | | | Investment in ADNOC Drilling | 205,616 | | | 205,616 | | | — | | | — | | | Total | 292,919 | | | 259,106 | | | 33,813 | | | — | | | | | | | | | | | Long-term investments: | | | | | | | | | Recurring fair value measurements: | | | | | | | | | Equity securities: | | | | | | | | | Non-qualified supplemental savings plan | 15,633 | | | 15,633 | | | — | | | — | | | Investment in Tamboran | 20,958 | | | 20,958 | | | — | | | — | | | Debt securities: | | | | | | | | | Investment in Galileo, net | 27,044 | | | — | | | — | | | 27,044 | | | Geothermal debt securities, net | 2,000 | | | — | | | — | | | 2,000 | | | Other debt securities | 4,588 | | | 4,338 | | | — | | | 250 | | | Total | 70,223 | | | 40,929 | | | — | | | 29,294 | |
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| Schedule of Reconciliation of Long Term Debt Securities Available For Sale, Classified as Level 3 |
The following table reconciles changes in the fair value of our Level 3 assets for the periods presented below: | | | | | | | | | | | | | Three Months Ended
December 31, | | (in thousands) | 2024 | | 2023 | | Assets at beginning of period | $ | 29,294 | | | $ | 37,440 | | | | | | | Accrued interest | 455 | | | 433 | | Total losses: | | | | | Included in earnings | — | | | (5) | | | Assets at end of period | $ | 29,749 | | | $ | 37,868 | |
The following table reconciles changes in the balance of our equity securities, without readily determinable fair values, including investments that have been marked to fair value on a nonrecurring basis, for the periods presented below: | | | | | | | | | | | | | Three Months Ended
December 31, | | (in millions) | 2024 | | 2023 | | Assets at beginning of period | $ | 30,090 | | | $ | 28,232 | | | Purchases | 646 | | | 291 | | Total gains: | | | | | Included in earnings | 109 | | | — | | | Assets at end of period | $ | 30,845 | | | $ | 28,523 | |
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| Schedule of Supplemental Fair Value Information about Long-Term Fixed-Rate Debt |
The following information presents the supplemental fair value information for our long-term fixed-rate debt at December 31, 2024 and September 30, 2024: | | | | | | | | | | | | | December 31, | | September 30, | | (in millions) | 2024 | | 2024 | | Long-term debt, net | | | | | Carrying value | 1,781.7 | | | 1,782.2 | | | Fair value | 1,666.5 | | | 1,702.9 | |
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