Investments - Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Amortized Cost
Due in one year or less	$ 144,465	$ 201,881
Due after one year through five years	154,981	35,970
Amortized Cost	299,446	237,851
Fair Value
Due in one year or less	144,461	201,864
Due after one year through five years	154,733	35,908
Debt Securities, Held-to-maturity, Fair Value, Total	$ 299,194	$ 237,772

Amount, after allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity).

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