Investments Available-for-sale Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Costs	$ 62,421	$ 64,851
Gross Unrealized Holding Gains	202	2
Gross Unrealized Holding Losses	(2)	(29)
Fair Value	62,621	64,824
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Costs	14,932	13,932
Gross Unrealized Holding Gains	11	1
Gross Unrealized Holding Losses	0	(2)
Fair Value	14,943	13,931
Corporate notes/bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Costs	43,965	36,620
Gross Unrealized Holding Gains	163	1
Gross Unrealized Holding Losses	(2)	(24)
Fair Value	44,126	36,597
U.S. Treasuries
Debt Securities, Available-for-sale [Line Items]
Amortized Costs	2,254	4,513
Gross Unrealized Holding Gains	11	0
Gross Unrealized Holding Losses	0	(1)
Fair Value	2,265	4,512
U.S. Government agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Costs	1,270	9,786
Gross Unrealized Holding Gains	17	0
Gross Unrealized Holding Losses	0	(2)
Fair Value	$ 1,287	$ 9,784

Amount, before tax, of unrealized gain 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).

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