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Marketable Securities - Schedule of the Cost Basis and Fair Value of Available-for-sale Securities by Contractual Maturity Date (Details) - USD ($)
$ in Thousands
Mar. 31, 2021
Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]    
Amortized Cost $ 122,706 $ 205,382
Estimated Fair Market Value $ 122,729 $ 205,402