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Fair Value Measurements (Tables) | 12 Months Ended
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Dec. 31, 2020
Fair Value Measurements |
Schedule of assets measured on a recurring basis at fair value | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ |  | Level 1 |  | Level 2 |  | Level 3 |  | Total
​ | ​ | (in thousands)
December 31, 2020 | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Cash equivalents | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Certificate of deposits and time deposits | ​ | $ | 59,168 | ​ | $ | — | ​ | $ | — | ​ | $ | 59,168
Commercial paper | ​ | ​ | — | ​ | ​ | 2,000 | ​ | ​ | — | ​ | ​ | 2,000
U.S. treasuries | ​ | ​ | 24,997 | ​ | ​ | — | ​ | ​ | — | ​ | ​ | 24,997
Total | ​ | $ | 84,165 | ​ | $ | 2,000 | ​ | $ | — | ​ | $ | 86,165
Short-term investments | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
U.S. treasuries | ​ | $ | 149,219 | ​ | $ | — | ​ | $ | — | ​ | $ | 149,219
Corporate debt | ​ | ​ | — | ​ | ​ | 32,554 | ​ | ​ | — | ​ | ​ | 32,554
Commercial paper | ​ | ​ | — | ​ | ​ | 7,998 | ​ | ​ | — | ​ | ​ | 7,998
Total | ​ | $ | 149,219 | ​ | $ | 40,552 | ​ | $ | — | ​ | $ | 189,771
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
December 31, 2019 | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Cash equivalents | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Certificate of deposits and time deposits | ​ | $ | 67,009 | ​ | $ | — | ​ | $ | — | ​ | $ | 67,009
Commercial paper | ​ | ​ | — | ​ | ​ | 10,484 | ​ | ​ | — | ​ | ​ | 10,484
Corporate debt | ​ | ​ | — | ​ | ​ | 1,000 | ​ | ​ | — | ​ | ​ | 1,000
Total | ​ | $ | 67,009 | ​ | $ | 11,484 | ​ | $ | — | ​ | $ | 78,493
Short-term investments | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
U.S. treasuries | ​ | $ | 105,130 | ​ | $ | — | ​ | $ | — | ​ | $ | 105,130
Government agency securities | ​ | ​ | — | ​ | ​ | 1,139 | ​ | ​ | — | ​ | ​ | 1,139
Corporate debt | ​ | ​ | — | ​ | ​ | 6,002 | ​ | ​ | — | ​ | ​ | 6,002
Commercial paper | ​ | ​ | — | ​ | ​ | 2,981 | ​ | ​ | — | ​ | ​ | 2,981
Total | ​ | $ | 105,130 | ​ | $ | 10,122 | ​ | $ | — | ​ | $ | 115,252

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- Definition Tabular disclosure of assets, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, by class that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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