Cash and Cash Equivalents and Investments (Details 1) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Cash and Cash Equivalents
Fair Value
Amortized Cost	$ 97,652	$ 126,263
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	97,652	126,263
U.S. Treasury Securities
Fair Value
Amortized Cost	15,243
Gross Unrealized Gains	2
Gross Unrealized Losses	0
Estimated Fair Value	15,245
Total Short-term Investments
Fair Value
Amortized Cost	43,704	26,018
Gross Unrealized Gains	12	5
Gross Unrealized Losses	(7)	(11)
Estimated Fair Value	43,709	26,012
Total Cash and Cash Equivalents and Investments
Fair Value
Amortized Cost	141,356	152,281
Gross Unrealized Gains	12	5
Gross Unrealized Losses	(7)	(11)
Estimated Fair Value	141,361	152,275
Corporate Debt Securities
Fair Value
Amortized Cost	28,461	26,018
Gross Unrealized Gains	10	5
Gross Unrealized Losses	7	(11)
Estimated Fair Value	$ 28,464	$ 26,012

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount of investment in debt and equity securities categorized neither as trading securities nor held-to-maturity securities and intended be sold or mature one year or operating cycle, if longer.

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