Marketable Securities - AFS Debt Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Marketable securities available for sale, consisting of debt securities:
Amortized Cost	$ 148,539
Gross Unrealized Losses	(212)
Estimated Market Value	148,327
Marketable securities		$ 0
Commercial paper
Marketable securities available for sale, consisting of debt securities:
Amortized Cost	57,369
Estimated Market Value	57,369
Corporate debt securities
Marketable securities available for sale, consisting of debt securities:
Amortized Cost	39,825
Gross Unrealized Losses	(77)
Estimated Market Value	39,748
Asset backed Securities
Marketable securities available for sale, consisting of debt securities:
Amortized Cost	26,736
Gross Unrealized Losses	(29)
Estimated Market Value	26,707
Government and agency securities
Marketable securities available for sale, consisting of debt securities:
Amortized Cost	24,609
Gross Unrealized Losses	(106)
Estimated Market Value	$ 24,503

Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

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Amount of investment in marketable security.

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