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Fair Value Measurements (Tables) | 9 Months Ended
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Sep. 30, 2020
Fair Value Measurements |
Schedule of assets measured at fair value on a recurring basis | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Fair Value Measurements as of September 30, 2020
​ |  | Total |  | Level 1 |  | Level 2 |  | Level 3
Cash and cash equivalents | ​ | $ | 418,228 | ​ | $ | 418,228 | ​ | $ | — | ​ | $ | —
Marketable securities | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Bonds and bond funds | ​ | $ | 95,183 | ​ | $ | — | ​ | $ | 95,183 | ​ | $ | —
Commercial paper | ​ |  | 308,610 | ​ |  | — | ​ |  | 308,610 | ​ |  | —
​ | ​ | ​ | 403,793 | ​ |  | — | ​ |  | 403,793 | ​ |  | —
Total assets measured at fair value | ​ | $ | 822,021 | ​ | $ | 418,228 | ​ | $ | 403,793 | ​ | $ | —
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​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Fair Value Measurements as of December 31, 2019
​ |  | Total |  | Level 1 |  | Level 2 |  | Level 3
Cash and cash equivalents | ​ | $ | 87,206 | ​ | $ | 87,206 | ​ | $ | — | ​ | $ | —
Marketable securities | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Bonds and bond funds | ​ | $ | 267,243 | ​ | $ | — | ​ | $ | 267,243 | ​ | $ | —
Commercial paper | ​ |  | 165,723 | ​ |  | — | ​ |  | 165,723 | ​ |  | —
​ | ​ | ​ | 432,966 | ​ |  | — | ​ |  | 432,966 | ​ |  | —
Total assets measured at fair value | ​ | $ | 520,172 | ​ | $ | 87,206 | ​ | $ | 432,966 | ​ | $ | —
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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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