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Financial Instruments - Summary of Fair Value and Amortized Cost of Cash Equivalents and Available-for-sale Investments by Major Security Type (Details) - USD ($)
$ in Thousands
Sep. 30, 2020
Dec. 31, 2019
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Cash equivalents and investments, Amortized cost $ 131,019 $ 138,447
Cash equivalents and investments, Unrealized gain 195 157
Cash equivalents and investments, Unrealized loss   (1)
Cash equivalents and investments, Estimated Fair Value 131,214 138,603
Cash equivalents, Estimated Fair Value 46,243 10,621
Investments, Estimated Fair Value 84,971  
Short-term investments 84,971 104,690
Long-term investments   23,292
Money Market Fund    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Cash equivalents, Amortized Cost 46,243 10,621
Cash equivalents, Estimated Fair Value 46,243 10,621
U.S. treasury bills    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Investments, Amortized Cost 29,988  
Investments, Unrealized Gain 1  
Investments, Unrealized Loss 0  
Investments, Estimated Fair Value 29,989  
Corporate Debt Securities    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Investments, Amortized Cost 29,168 41,556
Investments, Unrealized Gain 177 113
Investments, Unrealized Loss 0 (1)
Investments, Estimated Fair Value 29,345 41,668
Asset Backed Securities    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Investments, Amortized Cost 5,157 28,762
Investments, Unrealized Gain 17 25
Investments, Unrealized Loss 0 0
Investments, Estimated Fair Value 5,174 28,787
Commercial Paper    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Investments, Amortized Cost 20,463 35,016
Investments, Unrealized Gain 0 0
Investments, Unrealized Loss 0 0
Investments, Estimated Fair Value $ 20,463 35,016
U.S. Government Bonds    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Investments, Amortized Cost   22,492
Investments, Unrealized Gain   19
Investments, Unrealized Loss   0
Investments, Estimated Fair Value   $ 22,511