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Cash Equivalents and Marketable Securities - Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019
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Cash Equivalents and Marketable Securities |  |
Total cash equivalents and marketable securities, Amortized Cost | $ 304,142 | $ 131,699
Total cash equivalents and marketable securities, Gross Unrealized Gains | 12 | 27
Total cash equivalents and marketable securities, Gross Unrealized Losses | (10) | (8)
Total cash equivalents and marketable securities, Fair Value | 304,144 | 131,718
Corporate debt securities |  |
Cash Equivalents and Marketable Securities |  |
Total cash equivalents and marketable securities, Amortized Cost | 27,592 | 33,653
Total cash equivalents and marketable securities, Gross Unrealized Gains | 2 | 11
Total cash equivalents and marketable securities, Gross Unrealized Losses | (4) | (2)
Total cash equivalents and marketable securities, Fair Value | 27,590 | 33,662
U.S. Treasury and agency securities |  |
Cash Equivalents and Marketable Securities |  |
Total cash equivalents and marketable securities, Amortized Cost | 183,203 | 40,798
Total cash equivalents and marketable securities, Gross Unrealized Gains | 10 | 14
Total cash equivalents and marketable securities, Gross Unrealized Losses | (3) | (2)
Total cash equivalents and marketable securities, Fair Value | 183,210 | 40,810
Money Market Funds |  |
Cash Equivalents and Marketable Securities |  |
Total cash equivalents and marketable securities, Amortized Cost | 27,481 | 12,964
Total cash equivalents and marketable securities, Fair Value | 27,481 | 12,964
Commercial Paper |  |
Cash Equivalents and Marketable Securities |  |
Total cash equivalents and marketable securities, Amortized Cost | 65,866 | 44,284
Total cash equivalents and marketable securities, Gross Unrealized Gains |  | 2
Total cash equivalents and marketable securities, Gross Unrealized Losses | (3) | (4)
Total cash equivalents and marketable securities, Fair Value | $ 65,863 | $ 44,282

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- Definition This item represents the cost of debt and equity securities, including cash equivalents which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References No definition available. + Details
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- Definition Amount of unrealized gain before deducting unrealized loss on investments in debt and equity securities classified as cash equivalents and marketable securities. + References No definition available. + Details
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