| Schedule of Investments by Security Type |
Cash, cash equivalents and investments consisted of the following (in thousands): | | | | | | | | | | | | | | | | | | | | | | | | | March 31, 2024 | | Amortized Cost | | Gross Unrealized Gains | | Gross Unrealized Losses | | Fair Value | | Debt securities available-for-sale: | | | | | | | | | Commercial paper | $ | 203,117 | | | $ | — | | | $ | — | | | $ | 203,117 | | | Corporate bonds | 808,010 | | | 670 | | | (4,712) | | | 803,968 | | | U.S. Treasury and government-sponsored enterprises | 384,773 | | | 63 | | | (2,376) | | | 382,460 | | | Municipal bonds | 7,880 | | | — | | | (32) | | | 7,848 | | | Total debt securities available-for-sale | 1,403,780 | | | 733 | | | (7,120) | | | 1,397,393 | | | Cash | 19 | | | — | | | — | | | 19 | | | Money market funds | 133,132 | | | — | | | — | | | 133,132 | | | Certificates of deposit | 62,273 | | | — | | | — | | | 62,273 | | | Total cash, cash equivalents and investments | $ | 1,599,204 | | | $ | 733 | | | $ | (7,120) | | | $ | 1,592,817 | |
| | | | | | | | | | | | | | | | | | | | | | | | | December 31, 2023 | | Amortized Cost | | Gross Unrealized Gains | | Gross Unrealized Losses | | Fair Value | | Debt securities available-for-sale: | | | | | | | | | Commercial paper | $ | 214,016 | | | $ | — | | | $ | — | | | $ | 214,016 | | | Corporate bonds | 870,870 | | | 1,652 | | | (4,277) | | | 868,245 | | | U.S. Treasury and government-sponsored enterprises | 409,157 | | | 414 | | | (2,250) | | | 407,321 | | | Municipal bonds | 7,880 | | | 10 | | | (49) | | | 7,841 | | | Total debt securities available-for-sale | 1,501,923 | | | 2,076 | | | (6,576) | | | 1,497,423 | | | | | | | | | | | Money market funds | 154,287 | | | — | | | — | | | 154,287 | | | Certificates of deposit | 72,309 | | | — | | | — | | | 72,309 | | Total cash, cash equivalents and investments | $ | 1,728,519 | | | $ | 2,076 | | | $ | (6,576) | | | $ | 1,724,019 | |
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| Schedule of Fair Value and Gross Unrealized Losses of Investments Available-for-Sale in an Unrealized Loss Position |
The fair value and gross unrealized losses on debt securities available-for-sale in an unrealized loss position were as follows (in thousands): | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | March 31, 2024 | | In an Unrealized Loss Position Less than 12 Months | | In an Unrealized Loss Position 12 Months or Greater | | Total | | Fair Value | | Gross Unrealized Losses | | Fair Value | | Gross Unrealized Losses | | Fair Value | | Gross Unrealized Losses | | | | | | | | | | | | | | Corporate bonds | $ | 358,757 | | | $ | (1,814) | | | $ | 215,894 | | | $ | (2,898) | | | $ | 574,651 | | | $ | (4,712) | | | U.S. Treasury and government-sponsored enterprises | 217,026 | | | (951) | | | 109,223 | | | (1,425) | | | 326,249 | | | (2,376) | | | Municipal bonds | 1,879 | | | (1) | | | 5,969 | | | (31) | | | 7,848 | | | (32) | | Total | $ | 577,662 | | | $ | (2,766) | | | $ | 331,086 | | | $ | (4,354) | | | $ | 908,748 | | | $ | (7,120) | |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | December 31, 2023 | | In an Unrealized Loss Position Less than 12 Months | | In an Unrealized Loss Position 12 Months or Greater | | Total | | Fair Value | | Gross Unrealized Losses | | Fair Value | | Gross Unrealized Losses | | Fair Value | | Gross Unrealized Losses | | Corporate bonds | $ | 255,958 | | | $ | (847) | | | $ | 281,837 | | | $ | (3,430) | | | $ | 537,795 | | | $ | (4,277) | | | U.S. Treasury and government-sponsored enterprises | 163,339 | | | (406) | | | 155,452 | | | (1,844) | | | 318,791 | | | (2,250) | | Municipal bonds | — | | | — | | | 5,951 | | | (49) | | | 5,951 | | | (49) | | Total | $ | 419,297 | | | $ | (1,253) | | | $ | 443,240 | | | $ | (5,323) | | | $ | 862,537 | | | $ | (6,576) | |
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| Schedule of Fair Value of Cash Equivalents and Investments by Contractual Maturity |
The fair values of debt securities available-for-sale by contractual maturity were as follows (in thousands): | | | | | | | | | | | | | March 31, 2024 | | December 31, 2023 | | Maturing in one year or less | $ | 767,832 | | | $ | 768,706 | | | Maturing after one year through five years | 629,561 | | | 728,717 | | | Total debt securities available-for-sale | $ | 1,397,393 | | | $ | 1,497,423 | | | | | |
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