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Cash Equivalents and Marketable Securities - Schedule of Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Thousands | Jun. 30, 2020 | Dec. 31, 2019 | Jun. 30, 2019
--- | --- | --- | ---
Cash And Cash Equivalents [Line Items] |  |  |
Amortized Cost Basis | $ 204,493 | $ 131,499 |
Unrealized Gains | 402 | 168 |
Unrealized (Losses) | (4) | (3) |
Fair Value | 204,891 | 131,664 |
Less amounts classified as cash equivalents, Amortized Cost Basis | (65,348) | (4,960) | $ (19,390)
Marketable Securities |  |  |
Cash And Cash Equivalents [Line Items] |  |  |
Amortized Cost Basis | 141,264 | 128,348 |
Unrealized Gains | 402 | 168 |
Unrealized (Losses) | (4) | (3) |
Fair Value | 141,662 | 128,513 |
Cash Equivalents |  |  |
Cash And Cash Equivalents [Line Items] |  |  |
Less amounts classified as cash equivalents, Amortized Cost Basis | (63,229) | (3,151) |
Less amounts classified as cash equivalents, Fair Value | (63,229) | (3,151) |
Money Market Funds |  |  |
Cash And Cash Equivalents [Line Items] |  |  |
Amortized Cost Basis | 63,229 | 3,151 |
Unrealized Gains | 0 | 0 |
Unrealized (Losses) | 0 | 0 |
Fair Value | 63,229 | 3,151 |
Commercial Paper |  |  |
Cash And Cash Equivalents [Line Items] |  |  |
Amortized Cost Basis | 34,901 | 4,952 |
Unrealized Gains | 0 | 0 |
Unrealized (Losses) | 0 | 0 |
Fair Value | 34,901 | 4,952 |
Corporate Debt Securities |  |  |
Cash And Cash Equivalents [Line Items] |  |  |
Amortized Cost Basis | 61,118 | 69,423 |
Unrealized Gains | 170 | 79 |
Unrealized (Losses) | (4) | (3) |
Fair Value | 61,284 | 69,499 |
Asset-backed Securities |  |  |
Cash And Cash Equivalents [Line Items] |  |  |
Amortized Cost Basis | 16,096 | 27,005 |
Unrealized Gains | 121 | 50 |
Unrealized (Losses) | 0 | 0 |
Fair Value | 16,217 | 27,055 |
U.S. Government Agencies |  |  |
Cash And Cash Equivalents [Line Items] |  |  |
Amortized Cost Basis | 29,149 | 26,968 |
Unrealized Gains | 111 | 39 |
Unrealized (Losses) | 0 | 0 |
Fair Value | $ 29,260 | $ 27,007 |

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