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SIGNIFICANT ACCOUNTING POLICIES - Marketable Securities (Details) - USD ($) $ in Thousands | Dec. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Marketable Securities [Line Items] |  |
Total marketable securities | $ 81,724 | $ 51,857
U.S. Treasury securities |  |
Marketable Securities [Line Items] |  |
Total marketable securities | 901 | 28,901
Municipal bonds |  |
Marketable Securities [Line Items] |  |
Total marketable securities | 1,978 | 0
Corporate notes and bonds |  |
Marketable Securities [Line Items] |  |
Total marketable securities | 57,685 | 22,956
Commercial paper |  |
Marketable Securities [Line Items] |  |
Total marketable securities | $ 21,160 | $ 0

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- Definition Amount of investment in marketable security. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.4) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details
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