Investments (Details 2) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Short-term Investments [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 139,372	$ 121,616
Unrealized Losses	(16)	(28)
Unrealized Gains	319	25
Estimated Fair Value	139,675	121,613
Long-term Investments [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	13,224	39,413
Unrealized Losses		(1)
Unrealized Gains	9	28
Estimated Fair Value	$ 13,233	$ 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	$ 49,494	$ 50,445
Unrealized Losses		(4)
Unrealized Gains	79	16
Estimated Fair Value	$ 49,573	$ 50,457
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	1 or less
Amortized Cost	$ 89,878	$ 71,171
Unrealized Losses	(16)	(24)
Unrealized Gains	240	9
Estimated Fair Value	$ 90,102	$ 71,156
Corporate debt securities \| Non-current Assets [Member]
Schedule Of Available For Sale Securities [Line Items]
Maturity (in years)	Greater than 1	Greater than 1
Amortized Cost	$ 13,224	$ 29,572
Unrealized Losses		(1)
Unrealized Gains	9	23
Estimated Fair Value	$ 13,233	$ 29,594

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