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Investments, Summary of Investments (Details) $ in Thousands | 6 Months Ended |
--- | --- | ---
Jun. 30, 2024 USD ($) Company | Dec. 31, 2023 USD ($)
Ownership Interests in Private and Public Companies [Abstract] |  |  |
Number of private companies in which there is an equity ownership interest of less than 20% | Company |  | 7 |
Number of public companies in which there is an equity ownership interest of less than 20% | Company |  | 3 |
Available-for-sale Debt Securities with Maturity of One Year or Less [Abstract] |  |  |
Amortized cost |  | $ 1,343,698 | $ 1,316,219
Gross unrealized gains |  | 67 | 415
Gross unrealized losses |  | (3,026) | (5,238)
Estimated fair value |  | 1,340,739 | 1,311,396
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract] |  |  |
Amortized cost |  | 462,896 | 651,628
Gross unrealized gains |  | 275 | 3,063
Gross unrealized losses |  | (2,334) | (1,197)
Estimated fair value |  | 460,837 | 653,494
Available-for-sale Debt Securities [Abstract] |  |  |
Amortized cost |  | 1,806,594 | 1,967,847
Gross unrealized gains |  | 342 | 3,478
Gross unrealized losses |  | (5,360) | (6,435)
Estimated fair value |  | 1,801,576 | 1,964,890
Equity Securities [Abstract] |  |  |
Amortized cost |  | 35,012 | 35,012
Gross unrealized gains |  | 25,335 | 25,237
Gross unrealized losses |  | (12,470) | (10,957)
Estimated fair value |  | 47,877 | 49,292
Available-for-sale Debt and Equity Securities [Abstract] |  |  |
Amortized cost |  | 1,841,606 | 2,002,859
Gross unrealized gains |  | 25,677 | 28,715
Gross unrealized losses |  | (17,830) | (17,392)
Estimated fair value |  | 1,849,453 | 2,014,182
Corporate Debt Securities [Member] |  |  |
Available-for-sale Debt Securities with Maturity of One Year or Less [Abstract] |  |  |
Amortized cost | [1] | 552,837 | 559,967
Gross unrealized gains |  | 36 | 157
Gross unrealized losses |  | (1,569) | (2,625)
Estimated fair value |  | 551,304 | 557,499
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract] |  |  |
Amortized cost |  | 218,639 | 243,151
Gross unrealized gains |  | 191 | 1,270
Gross unrealized losses |  | (874) | (692)
Estimated fair value |  | 217,956 | 243,729
Debt Securities Issued by U.S. Government Agencies [Member] |  |  |
Available-for-sale Debt Securities with Maturity of One Year or Less [Abstract] |  |  |
Amortized cost |  | 121,781 | 224,711
Gross unrealized gains |  | 5 | 64
Gross unrealized losses |  | (310) | (611)
Estimated fair value |  | 121,476 | 224,164
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract] |  |  |
Amortized cost |  | 115,349 | 110,138
Gross unrealized gains |  | 72 | 547
Gross unrealized losses |  | (317) | (21)
Estimated fair value |  | 115,104 | 110,664
Debt Securities Issued by the U.S. Treasury [Member] |  |  |
Available-for-sale Debt Securities with Maturity of One Year or Less [Abstract] |  |  |
Amortized cost | [1] | 650,997 | 513,784
Gross unrealized gains |  | 12 | 152
Gross unrealized losses |  | (1,105) | (1,889)
Estimated fair value |  | 649,904 | 512,047
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract] |  |  |
Amortized cost |  | 127,240 | 294,873
Gross unrealized gains |  | 12 | 1,239
Gross unrealized losses |  | (1,135) | (480)
Estimated fair value |  | 126,117 | 295,632
Debt Securities Issued by States of the U.S. and Political Subdivisions of the States [Member] |  |  |
Available-for-sale Debt Securities with Maturity of One Year or Less [Abstract] |  |  |
Amortized cost |  | 18,083 | 17,757
Gross unrealized gains |  | 14 | 42
Gross unrealized losses |  | (42) | (113)
Estimated fair value |  | 18,055 | 17,686
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract] |  |  |
Amortized cost |  | 1,668 | 3,466
Gross unrealized gains |  | 0 | 7
Gross unrealized losses |  | (8) | (4)
Estimated fair value |  | 1,660 | 3,469
Publicly Traded Equity Securities [Member] |  |  |
Equity Securities [Abstract] |  |  |
Amortized cost | [2] | 11,897 | 11,897
Gross unrealized gains |  | 334 | 236
Gross unrealized losses |  | (5,377) | (5,832)
Estimated fair value |  | 6,854 | 6,301
Available-for-sale Debt and Equity Securities [Abstract] |  |  |
Unrealized gain on equity securities |  | 600 |
Privately Held Equity Securities [Member] |  |  |
Equity Securities [Abstract] |  |  |
Amortized cost | [3] | 23,115 | 23,115
Gross unrealized gains |  | 25,001 | 25,001
Gross unrealized losses |  | (7,093) | (5,125)
Estimated fair value |  | 41,023 | $ 42,991
Available-for-sale Debt and Equity Securities [Abstract] |  |  |
Unrealized loss on equity securities |  | $ (2,000) |
[1] | Includes investments classified as cash equivalents in our condensed consolidated balance sheets.
[2] | Our publicly traded equity securities are included in other current assets. We recognize publicly traded equity securities at fair value. In the six months ended June 30, 2024, we recorded a $0.6 million net unrealized gain in our condensed consolidated statements of operations related to changes in the fair value of our investments in publicly traded companies.
[3] | Our privately held equity securities are included in deposits and other assets. We recognize our privately held equity securities at cost minus impairments, plus or minus changes resulting from observable price changes in orderly transactions for the identical or similar investment of the same issuer, which are Level 3 inputs. In the six months ended June 30, 2024, we recorded a loss of $2.0 million in our condensed consolidated statements of operations related to changes in the fair value of our investments in privately held companies.

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