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Investments, Summary of Investments (Details) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2022 USD ($) Company | Dec. 31, 2021 USD ($)
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 |
Summary of Investments [Abstract] |  |  |
Amortized cost |  | $ 1,602,517 | $ 1,278,684
Gross unrealized gains |  | 20,880 | 25,115
Gross unrealized losses |  | (23,308) | (5,148)
Estimated fair value |  | $ 1,600,089 | 1,298,651
Number of publicly traded companies in which there is an investment included in other current assets | Company |  | 2 |
Bicycle [Member] |  |  |
Summary of Investments [Abstract] |  |  |
Gross unrealized losses |  | $ (3,200) |
ProQR [Member] |  |  |
Summary of Investments [Abstract] |  |  |
Gross unrealized losses |  | (3,400) |
Available-for-sale Securities [Member] |  |  |
Summary of Investments [Abstract] |  |  |
Amortized cost |  | 1,567,505 | 1,251,172
Gross unrealized gains |  | 227 | 1,263
Gross unrealized losses |  | (19,034) | (4,311)
Estimated fair value |  | 1,548,698 | 1,248,124
Available-for-sale Securities [Member] | Securities with Maturity of One Year or Less [Member] |  |  |
Summary of Investments [Abstract] |  |  |
Amortized cost |  | 949,813 | 612,557
Gross unrealized gains |  | 133 | 792
Gross unrealized losses |  | (3,423) | (345)
Estimated fair value |  | 946,523 | 613,004
Available-for-sale Securities [Member] | Securities with Maturity of More than One Year [Member] |  |  |
Summary of Investments [Abstract] |  |  |
Amortized cost |  | 617,692 | 638,615
Gross unrealized gains |  | 94 | 471
Gross unrealized losses |  | (15,611) | (3,966)
Estimated fair value |  | 602,175 | 635,120
Corporate Debt Securities [Member] | Securities with Maturity of One Year or Less [Member] |  |  |
Summary of Investments [Abstract] |  |  |
Amortized cost | [1] | 420,081 | 383,870
Gross unrealized gains |  | 131 | 728
Gross unrealized losses |  | (1,766) | (226)
Estimated fair value |  | 418,446 | 384,372
Corporate Debt Securities [Member] | Securities with Maturity of More than One Year [Member] |  |  |
Summary of Investments [Abstract] |  |  |
Amortized cost |  | 345,813 | 382,000
Gross unrealized gains |  | 24 | 331
Gross unrealized losses |  | (10,275) | (2,644)
Estimated fair value |  | 335,562 | 379,687
Debt Securities Issued by U.S. Government Agencies [Member] | Securities with Maturity of One Year or Less [Member] |  |  |
Summary of Investments [Abstract] |  |  |
Amortized cost |  | 34,407 | 48,493
Gross unrealized gains |  | 0 | 19
Gross unrealized losses |  | (49) | (18)
Estimated fair value |  | 34,358 | 48,494
Debt Securities Issued by U.S. Government Agencies [Member] | Securities with Maturity of More than One Year [Member] |  |  |
Summary of Investments [Abstract] |  |  |
Amortized cost |  | 72,844 | 72,935
Gross unrealized gains |  | 0 | 0
Gross unrealized losses |  | (1,974) | (561)
Estimated fair value |  | 70,870 | 72,374
Debt Securities Issued by the U.S. Treasury [Member] | Securities with Maturity of One Year or Less [Member] |  |  |
Summary of Investments [Abstract] |  |  |
Amortized cost | [1] | 330,358 | 45,424
Gross unrealized gains |  | 1 | 0
Gross unrealized losses |  | (1,133) | (64)
Estimated fair value |  | 329,226 | 45,360
Debt Securities Issued by the U.S. Treasury [Member] | Securities with Maturity of More than One Year [Member] |  |  |
Summary of Investments [Abstract] |  |  |
Amortized cost |  | 164,040 | 137,635
Gross unrealized gains |  | 70 | 139
Gross unrealized losses |  | (2,544) | (500)
Estimated fair value |  | 161,566 | 137,274
Debt Securities Issued by States of the U.S. and Political Subdivisions of the States [Member] | Securities with Maturity of One Year or Less [Member] |  |  |
Summary of Investments [Abstract] |  |  |
Amortized cost |  | 158,548 | 134,770
Gross unrealized gains |  | 1 | 45
Gross unrealized losses |  | (376) | (37)
Estimated fair value |  | 158,173 | 134,778
Debt Securities Issued by States of the U.S. and Political Subdivisions of the States [Member] | Securities with Maturity of More than One Year [Member] |  |  |
Summary of Investments [Abstract] |  |  |
Amortized cost |  | 34,995 | 39,909
Gross unrealized gains |  | 0 | 1
Gross unrealized losses |  | (818) | (224)
Estimated fair value |  | 34,177 | 39,686
Other Municipal Debt Securities [Member] | Securities with Maturity of One Year or Less [Member] |  |  |
Summary of Investments [Abstract] |  |  |
Amortized cost |  | 6,419 |
Gross unrealized gains |  | 0 |
Gross unrealized losses |  | (99) |
Estimated fair value |  | 6,320 |
Other Municipal Debt Securities [Member] | Securities with Maturity of More than One Year [Member] |  |  |
Summary of Investments [Abstract] |  |  |
Amortized cost |  |  | 6,136
Gross unrealized gains |  |  | 0
Gross unrealized losses |  |  | (37)
Estimated fair value |  |  | 6,099
Equity Securities [Member] |  |  |
Summary of Investments [Abstract] |  |  |
Amortized cost |  | 35,012 | 27,512
Gross unrealized gains |  | 20,653 | 23,852
Gross unrealized losses |  | (4,274) | (837)
Estimated fair value |  | 51,391 | 50,527
Equity Securities in Publicly Traded Company [Member] |  |  |
Summary of Investments [Abstract] |  |  |
Amortized cost | [2] | 11,897 | 11,897
Gross unrealized gains |  | 3,946 | 7,145
Gross unrealized losses |  | (4,274) | (837)
Estimated fair value |  | 11,569 | 18,205
Equity Securities in Private Companies [Member] |  |  |
Summary of Investments [Abstract] |  |  |
Amortized cost | [3] | 23,115 | 15,615
Gross unrealized gains |  | 16,707 | 16,707
Gross unrealized losses |  | 0 | 0
Estimated fair value |  | $ 39,822 | $ 32,322
[1] | Includes investments classified as cash equivalents on our condensed consolidated balance sheet.
[2] | Our equity securities included in other current assets consisted of our investments in two publicly traded companies, ProQR and Bicycle, which we classify as Level 1 and Level 3 investments, respectively. We recognize publicly traded equity securities at fair value. In the three months ended March 31, 2022, we recognized a $3.4 million and a $3.2 million unrealized loss on our condensed consolidated statement of operations related to our investments in ProQR and Bicycle, respectively. In the three months ended March 31, 2021, our equity securities included in other current assets only consisted of ProQR.
[3] | Our equity securities included in deposits and other assets consisted of our investments in privately held companies. We recognize our private company 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.

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