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Cash and Cash Equivalents - Schedule of Cash and Cash Equivalents by Significant Investment Category (Details) - USD ($)
$ in Thousands
Jun. 30, 2021
Dec. 31, 2020
Jun. 30, 2020
Cash And Cash Equivalents And Short Term Investments [Line Items]      
Cash $ 3,570 $ 2,779  
Cash and cash equivalents and Short term investments, Amortized cost 20,240 38,173  
Cash and cash equivalents and Short term investments, Estimated fair value 20,240 38,173  
Cash and cash equivalents 20,240 38,173 $ 28,593
Money Market Funds | Level 1      
Cash And Cash Equivalents And Short Term Investments [Line Items]      
Cash equivalents $ 16,670 $ 35,394