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Fair Value of Financial Assets (Details) - USD ($) $ in Thousands | Mar. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Fair Value of Financial Assets and Liabilities |  |
Carrying amount of cash and cash equivalents and short term investments | $ 404,750 | $ 172,792
Fair value of financial assets and liabilities |  |
Marketable Securities | 317,479 | 71,938
Corporate Debt Securities and Commercial Paper |  |
Fair value of financial assets and liabilities |  |
Marketable Securities | 317,479 | 71,938
Recurring | Estimated fair value |  |
Fair value of financial assets and liabilities |  |
Fair value of assets | 403,594 | 171,362
Recurring | Commercial Paper | Estimated fair value |  |
Fair value of financial assets and liabilities |  |
Cash Equivalents | 4,750 |
Recurring | Corporate Debt Securities and Commercial Paper | Estimated fair value |  |
Fair value of financial assets and liabilities |  |
Cash Equivalents |  | 36,242
Marketable Securities | 317,479 | 71,938
Recurring | Money Market Funds | Estimated fair value |  |
Fair value of financial assets and liabilities |  |
Cash Equivalents | 81,365 | 63,182
Recurring | Level 1 | Estimated fair value |  |
Fair value of financial assets and liabilities |  |
Fair value of assets | 81,365 | 63,182
Recurring | Level 1 | Money Market Funds | Estimated fair value |  |
Fair value of financial assets and liabilities |  |
Cash Equivalents | 81,365 | 63,182
Recurring | Level 2 | Estimated fair value |  |
Fair value of financial assets and liabilities |  |
Fair value of assets | 322,229 | 108,180
Recurring | Level 2 | Commercial Paper | Estimated fair value |  |
Fair value of financial assets and liabilities |  |
Cash Equivalents | 4,750 |
Recurring | Level 2 | Corporate Debt Securities and Commercial Paper | Estimated fair value |  |
Fair value of financial assets and liabilities |  |
Cash Equivalents |  | 36,242
Marketable Securities | $ 317,479 | $ 71,938

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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121558606&loc=SL82898722-210454 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121553693&loc=d3e26610-111562 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563 + Details
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- Definition Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References No definition available. + Details
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- Definition Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid Investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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