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FAIR VALUE MEASUREMENTS - SECURITY TYPE (Details) - USD ($) $ in Thousands | Dec. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Included in cash and cash equivalents: |  |
Amortized Cost | $ 31,706 |
Estimated Fair Value | 31,706 |
Restricted cash: |  |
Amortized Cost | 364 | $ 363
Estimated Fair Value | 364 | 363
Marketable securities: |  |
Amortized Cost | 177,675 | 249,659
Gross Unrealized Gains | 4 | 111
Gross Unrealized Losses | (177) | (33)
Estimated Fair Value | 177,502 | 249,737
Money market funds |  |
Included in cash and cash equivalents: |  |
Amortized Cost | 24,207 | 4,356
Estimated Fair Value | 24,207 | 4,356
Restricted cash: |  |
Amortized Cost | 93 | 92
Estimated Fair Value | 93 | 92
Commercial paper |  |
Included in cash and cash equivalents: |  |
Amortized Cost | 7,499 |
Estimated Fair Value | 7,499 |
Certificate of deposit |  |
Restricted cash: |  |
Amortized Cost | 271 | 271
Estimated Fair Value | 271 | 271
U.S. Treasury securities (due in less than one year) |  |
Marketable securities: |  |
Amortized Cost | 15,585 | 5,608
Gross Unrealized Gains |  | 2
Gross Unrealized Losses | (18) |
Estimated Fair Value | 15,567 | 5,610
U.S. Treasury securities (due in one to two years) |  |
Marketable securities: |  |
Amortized Cost | 1,524 | 5,093
Gross Unrealized Gains |  | 2
Gross Unrealized Losses | (3) |
Estimated Fair Value | 1,521 | 5,095
Municipal securities (due in one to two years) |  |
Marketable securities: |  |
Amortized Cost | 3,000 |
Gross Unrealized Losses | (15) |
Estimated Fair Value | 2,985 |
Government-sponsored enterprise securities (due in less than one year) |  |
Marketable securities: |  |
Amortized Cost | 12,500 | 5,249
Gross Unrealized Gains |  | 3
Gross Unrealized Losses | (7) |
Estimated Fair Value | 12,493 | 5,252
Government-sponsored enterprise securities (due in one to two years) |  |
Marketable securities: |  |
Amortized Cost |  | 23,499
Gross Unrealized Gains |  | 7
Gross Unrealized Losses |  | (1)
Estimated Fair Value |  | 23,505
Commercial paper (due in less than one year) |  |
Marketable securities: |  |
Amortized Cost | 84,398 | 112,388
Gross Unrealized Gains | 2 | 29
Gross Unrealized Losses | (38) | (8)
Estimated Fair Value | 84,362 | 112,409
Corporate notes (due in less than one year) |  |
Marketable securities: |  |
Amortized Cost | 36,444 | 63,051
Gross Unrealized Gains | 2 | 35
Gross Unrealized Losses | (17) | (7)
Estimated Fair Value | 36,429 | 63,079
Corporate notes (due in one to two years) |  |
Marketable securities: |  |
Amortized Cost | 24,224 | 34,771
Gross Unrealized Gains |  | 33
Gross Unrealized Losses | (79) | (17)
Estimated Fair Value | $ 24,145 | $ 34,787

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