Fair Value Measurement | Note 2 - Fair Value Measurement The following table summarizes the Company’s investments at March 31, 2024 and December 31, 2023 measured at fair value on a recurring basis (in thousands): March 31, 2024 December 31, 2023 Gross Gross Unrealized Recorded Unrealized Recorded (Losses) (Losses) Cost Gains Basis Cost Gains Basis Current: Cash equivalents: Money market funds $ 18,549 $ — $ 18,549 $ 19,539 $ — $ 19,539 Total cash equivalents 18,549 — 18,549 19,539 — 19,539 Investments: Corporate bonds 32,319 ( 3,123 ) 29,196 34,472 ( 3,159 ) 31,313 U.S. government agency securities 12,806 ( 395 ) 12,411 12,830 ( 408 ) 12,422 U.S. treasuries 12,451 ( 1,369 ) 11,082 12,448 ( 1,253 ) 11,195 Mortgage backed securities 12,908 ( 2,677 ) 10,231 13,084 ( 2,454 ) 10,630 Asset backed securities 9,647 ( 157 ) 9,490 13,659 ( 187 ) 13,472 Emerging markets — — — 2,003 ( 8 ) 1,995 Total current investments 80,131 ( 7,721 ) 72,410 88,496 ( 7,469 ) 81,027 Restricted cash and investments (1) : U.S. treasuries 125,052 ( 7,032 ) 118,020 109,020 ( 6,415 ) 102,605 Corporate bonds 82,816 ( 9,022 ) 73,794 82,481 ( 8,454 ) 74,027 Mortgage backed securities 42,418 ( 5,874 ) 36,544 42,077 ( 5,216 ) 36,861 U.S. government agency securities 16,854 ( 1,170 ) 15,684 16,863 ( 1,199 ) 15,664 Mutual funds 9,641 — 9,641 8,941 — 8,941 Asset backed securities 799 ( 2 ) 797 799 — 799 Emerging markets 200 3 203 200 2 202 Money market funds 107 — 107 337 — 337 Total restricted cash and 277,887 ( 23,097 ) 254,790 260,718 ( 21,282 ) 239,436 Total investments $ 376,567 $ ( 30,818 ) $ 345,749 $ 368,753 $ ( 28,751 ) $ 340,002 (1) Included in restricted cash and investments within the condensed consolidated balance sheets as of March 31, 2024 and December 31, 2023 is restricted cash of $ 11.8 million and $ 3.6 million, respectively, which is excluded from the table above. Restricted cash and investments are classified as current and noncurrent on the balance sheet based on the nature of the restriction. The following table summarizes the Company’s investments at March 31, 2024 and December 31, 2023 measured at fair value on a recurring basis by fair value hierarchy level (in thousands): March 31, 2024 December 31, 2023 Total Total Recorded Recorded Basis Level 1 Level 2 Other (1) Basis Level 1 Level 2 Other (1) Cash equivalents: Money market funds $ 18,549 $ — $ — $ 18,549 $ 19,539 $ — $ — $ 19,539 Investments: Corporate bonds 29,196 — 29,196 — 31,313 — 31,313 — U.S. government 12,411 — 12,411 — 12,422 — 12,422 — U.S. treasuries 11,082 — 11,082 — 11,195 — 11,195 — Mortgage backed 10,231 — 10,231 — 10,630 — 10,630 — Asset backed securities 9,490 — 9,490 — 13,472 — 13,472 — Emerging markets — — — — 1,995 — 1,995 — Restricted cash and U.S. treasuries 118,020 — 118,020 — 102,605 — 102,605 — Corporate bonds 73,794 — 73,794 — 74,027 — 74,027 — Mortgage backed 36,544 — 36,544 — 36,861 — 36,861 — U.S. government 15,684 — 15,684 — 15,664 — 15,664 — Mutual funds 9,641 9,641 — — 8,941 8,941 — — Asset backed securities 797 — 797 — 799 — 799 — Emerging markets 203 — 203 — 202 — 202 — Money market funds 107 — — 107 337 — — 337 Total investments $ 345,749 $ 9,641 $ 317,452 $ 18,656 $ 340,002 $ 8,941 $ 311,185 $ 19,876 (1) Investments in money market funds measured at fair value using the net asset value per share practical expedient are not subject to hierarchy level classification disclosure. The Company invests in money market funds that seek to maintain a stable net asset value. These investments include commingled funds that comprise high-quality short-term securities representing liquid debt and monetary instruments where the redemption value is likely to be the fair value. Redemption is permitted daily without written notice. The following table summarizes the contractual maturities of the Company’s available-for-sale securities at March 31, 2024 and December 31, 2023. Actual maturities may differ from contractual maturities because borrowers may have the right to prepay obligations with or without prepayment penalties. The table also includes money market funds, which are classified as cash and cash equivalents on the Company’s consolidated balance sheets. March 31, 2024 (In thousands) Less than Between 1 to Between 5 to After 10 Years Total U.S. treasuries $ 71,700 $ 32,671 $ 24,731 — $ 129,102 Corporate bonds 4,920 67,561 30,339 170 102,990 U.S. government agency securities 39 27,018 1,038 — 28,095 Money market funds 18,656 — — — 18,656 Asset backed securities — 797 8,199 1,291 10,287 Emerging markets — — 203 — 203 Total $ 95,315 $ 128,047 $ 64,510 $ 1,461 $ 289,333 December 31, 2023 (In thousands) Less than Between 1 to Between 5 to After 10 Years Total U.S. treasuries $ 55,955 $ 32,706 $ 25,139 $ — $ 113,800 Corporate bonds 6,859 67,731 30,574 176 105,340 U.S. government agency securities 39 27,018 1,029 — 28,086 Money market funds 19,876 — — — 19,876 Asset backed securities — 799 12,182 1,290 14,271 Emerging markets 1,995 — 202 — 2,197 Total $ 84,724 $ 128,254 $ 69,126 $ 1,466 $ 283,570 The average contractual maturity of mortgage backed securities, which are excluded from the table above, was 21 and 23 years as of March 31, 2024 and December 31, 2023 , respectively. |