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Fair Value Measurements and Available for Sale Investments - Additional Information (Details) - USD ($) | Sep. 30, 2020 | Dec. 31, 2019
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Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Fair value hierarchy level 1 to level 2 | $ 0 | $ 0
Fair value hierarchy level 2 to level 1 | 0 | 0
2027 Notes | Level 2 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Fair value of convertible senior notes | 202,000,000.0 |
Prepaid Expenses and Other Current Assets |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Interest and securities receivable | $ 500,000 | $ 1,500,000

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