Investments (Tables)

12 Months Ended

Dec. 31, 2020

Investments

Schedule of amortized cost and fair value of available-for-sale securities

			Gross		Gross
	Amortized		Unrealized		Unrealized		Estimated
	Cost		Gains		Losses		Fair Value
	(in thousands)
December 31, 2020
U.S. treasuries	$	149,206	$	14	$	(1)	$	149,219
Corporate debt		32,588		—		(34)		32,554
Commercial paper		7,997		1		—		7,998
Total	$	189,791	$	15	$	(35)	$	189,771
December 31, 2019
U.S. treasuries	$	105,096	$	38	$	(4)	$	105,130
Government agency securities		1,139		—		—		1,139
Corporate debt		6,003		—		(1)		6,002
Commercial paper		2,981		—		—		2,981
Total	$	115,219	$	38	$	(5)	$	115,252

Schedule of fair value and unrealized losses of available-for-sale securities in a loss position

	December 31, 2020				December 31, 2019
			Gross				Gross
	Estimated		Unrealized		Estimated		Unrealized
	Fair Value		Losses		Fair Value		Losses
		(in thousands)
U.S. treasuries	$	19,991	$	(1)	$	22,943	$	(4)
Corporate debt		32,554		(34)		6,002		(1)
Total	$	52,545	$	(35)	$	28,945	$	(5)