Investments (Details 2) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Short-term Investments [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 121,616	$ 10,495
Unrealized Losses	(28)	(2)
Unrealized Gains	25
Estimated Fair Value	121,613	$ 10,493
Long-term Investments [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	39,413
Unrealized Losses	(1)
Unrealized Gains	28
Estimated Fair Value	$ 39,440
U.S. Treasury debt securities \| Current Assets [Member]
Schedule Of Available For Sale Securities [Line Items]
Maturity (in years)	1 or less	1 or less
Amortized Cost	$ 50,445	$ 10,495
Unrealized Losses	(4)	(2)
Unrealized Gains	16
Estimated Fair Value	$ 50,457	$ 10,493
U.S. Treasury debt securities \| Non-current Assets [Member]
Schedule Of Available For Sale Securities [Line Items]
Maturity (in years)	Greater than 1
Amortized Cost	$ 9,841
Unrealized Gains	5
Estimated Fair Value	$ 9,846
Corporate debt securities \| Current Assets [Member]
Schedule Of Available For Sale Securities [Line Items]
Maturity (in years)	1 or less
Amortized Cost	$ 71,171
Unrealized Losses	(24)
Unrealized Gains	9
Estimated Fair Value	$ 71,156
Corporate debt securities \| Non-current Assets [Member]
Schedule Of Available For Sale Securities [Line Items]
Maturity (in years)	Greater than 1
Amortized Cost	$ 29,572
Unrealized Losses	(1)
Unrealized Gains	23
Estimated Fair Value	$ 29,594

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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).

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