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Fair Value Measurements - Assets Measured at Fair Value On a Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | ---
Debt Securities, Available-for-Sale | $ 798,655 | $ 935,844
Cash equivalents |  |
Cash Equivalents | 71,237 | 147,463
Short-term |  |
Debt Securities, Available-for-Sale | 671,414 | 725,063
Long-term |  |
Debt Securities, Available-for-Sale | 56,004 | 63,318
Level 1 |  |
Debt Securities, Available-for-Sale | 33,613 | 88,073
Level 1 | Cash equivalents |  |
Cash Equivalents | 33,613 | 88,073
Level 1 | Short-term |  |
Debt Securities, Available-for-Sale | 0 | 0
Level 1 | Long-term |  |
Debt Securities, Available-for-Sale | 0 | 0
Level 2 |  |
Debt Securities, Available-for-Sale | 765,042 | 847,771
Level 2 | Cash equivalents |  |
Cash Equivalents | 37,624 | 59,390
Level 2 | Short-term |  |
Debt Securities, Available-for-Sale | 671,414 | 725,063
Level 2 | Long-term |  |
Debt Securities, Available-for-Sale | 56,004 | 63,318
Money market funds | Cash equivalents |  |
Cash Equivalents | 33,613 | 88,073
Money market funds | Level 1 | Cash equivalents |  |
Cash Equivalents | 33,613 | 88,073
Money market funds | Level 2 | Cash equivalents |  |
Cash Equivalents | 0 | 0
Commercial paper | Cash equivalents |  |
Cash Equivalents | 19,575 | 50,791
Commercial paper | Short-term |  |
Debt Securities, Available-for-Sale | 237,870 | 421,279
Commercial paper | Level 1 | Cash equivalents |  |
Cash Equivalents | 0 | 0
Commercial paper | Level 1 | Short-term |  |
Debt Securities, Available-for-Sale | 0 | 0
Commercial paper | Level 2 | Cash equivalents |  |
Cash Equivalents | 19,575 | 50,791
Commercial paper | Level 2 | Short-term |  |
Debt Securities, Available-for-Sale | 237,870 | 421,279
Federal agency debt securities | Cash equivalents |  |
Cash Equivalents | 8,201 | 0
Federal agency debt securities | Short-term |  |
Debt Securities, Available-for-Sale | 194,522 | 107,222
Federal agency debt securities | Long-term |  |
Debt Securities, Available-for-Sale | 12,135 | 20,050
Federal agency debt securities | Level 1 | Cash equivalents |  |
Cash Equivalents | 0 | 0
Federal agency debt securities | Level 1 | Short-term |  |
Debt Securities, Available-for-Sale | 0 | 0
Federal agency debt securities | Level 1 | Long-term |  |
Debt Securities, Available-for-Sale | 0 | 0
Federal agency debt securities | Level 2 | Cash equivalents |  |
Cash Equivalents | 8,201 | 0
Federal agency debt securities | Level 2 | Short-term |  |
Debt Securities, Available-for-Sale | 194,522 | 107,222
Federal agency debt securities | Level 2 | Long-term |  |
Debt Securities, Available-for-Sale | 12,135 | 20,050
US Treasury bonds | Cash equivalents |  |
Cash Equivalents | 2,000 | 0
US Treasury bonds | Short-term |  |
Debt Securities, Available-for-Sale | 14,126 | 0
US Treasury bonds | Level 1 | Cash equivalents |  |
Cash Equivalents | 0 | 0
US Treasury bonds | Level 1 | Short-term |  |
Debt Securities, Available-for-Sale | 0 | 0
US Treasury bonds | Level 2 | Cash equivalents |  |
Cash Equivalents | 2,000 | 0
US Treasury bonds | Level 2 | Short-term |  |
Debt Securities, Available-for-Sale | 14,126 | 0
Municipal debt securities | Cash equivalents |  |
Cash Equivalents | 7,848 | 8,599
Municipal debt securities | Short-term |  |
Debt Securities, Available-for-Sale | 13,914 | 30,426
Municipal debt securities | Long-term |  |
Debt Securities, Available-for-Sale | 0 | 7,580
Municipal debt securities | Level 1 | Cash equivalents |  |
Cash Equivalents | 0 | 0
Municipal debt securities | Level 1 | Short-term |  |
Debt Securities, Available-for-Sale | 0 | 0
Municipal debt securities | Level 1 | Long-term |  |
Debt Securities, Available-for-Sale | 0 | 0
Municipal debt securities | Level 2 | Cash equivalents |  |
Cash Equivalents | 7,848 | 8,599
Municipal debt securities | Level 2 | Short-term |  |
Debt Securities, Available-for-Sale | 13,914 | 30,426
Municipal debt securities | Level 2 | Long-term |  |
Debt Securities, Available-for-Sale | 0 | 7,580
Corporate debt securities | Short-term |  |
Debt Securities, Available-for-Sale | 210,982 | 166,136
Corporate debt securities | Long-term |  |
Debt Securities, Available-for-Sale | 43,869 | 35,688
Corporate debt securities | Level 1 | Short-term |  |
Debt Securities, Available-for-Sale | 0 | 0
Corporate debt securities | Level 1 | Long-term |  |
Debt Securities, Available-for-Sale | 0 | 0
Corporate debt securities | Level 2 | Short-term |  |
Debt Securities, Available-for-Sale | 210,982 | 166,136
Corporate debt securities | Level 2 | Long-term |  |
Debt Securities, Available-for-Sale | $ 43,869 | $ 35,688

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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (aa) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481830/320-10-45-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479130/326-30-45-1 + Details
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