Cash and Cash Equivalents and Investments (Details 1) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Cash and Cash Equivalents
Fair Value
Amortized Cost	$ 52,251	$ 36,112
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	52,251	36,112
U.S. Treasury Securities
Fair Value
Amortized Cost	38,796	235,463
Gross Unrealized Gains	40	94
Gross Unrealized Losses	0	(10)
Estimated Fair Value	38,836	235,547
Total Short-term Investments
Fair Value
Amortized Cost	59,160	235,463
Gross Unrealized Gains	41	94
Gross Unrealized Losses	(6)	(10)
Estimated Fair Value	59,195	235,547
Total Cash and Cash Equivalents and Investments
Fair Value
Amortized Cost	111,411	271,575
Gross Unrealized Gains	41	94
Gross Unrealized Losses	(6)	(10)
Estimated Fair Value	111,446	$ 271,659
Corporate Debt Securities
Fair Value
Amortized Cost	20,364
Gross Unrealized Gains			$ 1
Gross Unrealized Losses	6
Estimated Fair Value	$ 20,359

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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