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Marketable Securities and Fair Value Measurements (Tables) | 6 Months Ended
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Jun. 30, 2021
Marketable Securities and Fair Value Measurements [Abstract] |
Summary of marketable securities | The following tables present our marketable securities by security type: ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | As of June 30, 2021
​ |  | ​ | ​ |  | Gross |  | Gross |  | Estimated
​ | ​ | Amortized | ​ | Unrealized | ​ | Unrealized | ​ | Fair
(in thousands) | ​ | Cost | ​ | Gains | ​ | Losses | ​ | Value
U.S. treasury securities | ​ | $ | 33,117 | ​ | $ | 4 | ​ | $ | — | ​ | $ | 33,121
​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | As of December 31, 2020
​ |  | ​ | ​ |  | Gross |  | Gross |  | ​
​ | ​ | Amortized | ​ | Unrealized | ​ | Unrealized | ​ | Fair
(in thousands) | ​ | Cost | ​ | Gains | ​ | Losses | ​ | Value
U.S. treasury securities | ​ | $ | 129,446 | ​ | $ | 9 | ​ | $ | (4) | ​ | $ | 129,451
Commercial paper | ​ |  | 52,441 | ​ |  | — | ​ |  | — | ​ |  | 52,441
Corporate debt securities | ​ |  | 17,542 | ​ |  | 4 | ​ |  | — | ​ |  | 17,546
Total | ​ | $ | 199,429 | ​ | $ | 13 | ​ | $ | (4) | ​ | $ | 199,438
Summary of assets measured at fair value on a recurring basis | The following tables present our assets that are measured at fair value on a recurring basis and indicate the level within the fair value hierarchy of the valuation techniques that we utilized to determine such fair value: ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ |  | Fair Value Measurements at June 30, 2021 Using:
(in thousands) | ​ | Level 1 | ​ | Level 2 | ​ | Level 3 | ​ | Total
Cash equivalents: |  | ​ |  |  | ​ |  |  | ​ |  |  | ​ |
Money market funds | ​ | $ | 226,378 | ​ | $ | — | ​ | $ | — | ​ | $ | 226,378
Marketable securities: | ​ |  |  | ​ |  |  | ​ |  |  | ​ |  |
U.S. treasury securities | ​ |  | — | ​ |  | 33,121 | ​ |  | — | ​ |  | 33,121
​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ |  | Fair Value Measurements at December 31, 2020 Using:
(in thousands) |  | Level 1 |  | Level 2 |  | Level 3 |  | Total
Cash equivalents: | ​ | ​ |  |  | ​ |  |  | ​ |  |  | ​ |
Money market funds | ​ | $ | 63,827 | ​ | $ | — | ​ | $ | — | ​ | $ | 63,827
Marketable securities: | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
U.S. treasury securities | ​ | ​ | — | ​ | ​ | 129,451 | ​ | ​ | — | ​ | ​ | 129,451
Commercial paper | ​ | ​ | — | ​ | ​ | 52,441 | ​ | ​ | — | ​ | ​ | 52,441
Corporate debt securities | ​ | ​ | — | ​ | ​ | 17,546 | ​ | ​ | — | ​ | ​ | 17,546
Total | ​ | $ | 63,827 | ​ | $ | 199,438 | ​ | $ | — | ​ | $ | 263,265

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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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- Definition Tabular disclosure of marketable securities. This may consist of investments in certain debt and equity securities, short-term investments and other assets. + References No definition available. + Details
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