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Cash and Cash Equivalents - Schedule of Cash and Cash Equivalents by Significant Investment Category (Details) - USD ($)
$ in Thousands
Mar. 31, 2021
Dec. 31, 2020
Mar. 31, 2020
Cash And Cash Equivalents And Short Term Investments [Line Items]      
Cash $ 5,411 $ 2,779  
Cash and cash equivalents and Short term investments, Amortized cost 21,458 38,173  
Cash and cash equivalents and Short term investments, Estimated fair value 21,458 38,173  
Cash and cash equivalents 21,458 38,173 $ 22,533
Money Market Funds | Level 1      
Cash And Cash Equivalents And Short Term Investments [Line Items]      
Cash equivalents $ 16,047 $ 35,394