Fair Value of Financial Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value of Financial Assets and Liabilities

Schedule of financial assets and liabilities measured at fair value on a recurring basis

	Fair Value Measurements
	as of December 31, 2020 Using:
	Level 1		Level 2		Level 3		Total
Assets:
Restricted cash — money market funds	$	210	$	—	$	—	$	210
Cash equivalents — money market funds		22,942		—		—		22,942
Cash equivalents — U.S. Treasury notes		—		72,695		—		72,695
Short-term investments — U.S. Treasury notes		—		209,444		—		209,444
	$	23,152	$	282,139	$	—	$	305,291

	Fair Value Measurements
	as of December 31, 2019 Using:
	Level 1		Level 2		Level 3		Total
Assets:
Restricted cash — money market funds	$	210	$	—	$	—	$	210
Cash equivalents — money market funds		25,207		—		—		25,207
Cash equivalents — U.S. Treasury notes		—		10,192		—		10,192
Short-term investments — U.S. Treasury notes		—		186,452		—		186,452
	$	25,417	$	196,644	$	—	$	222,061

Schedule of short-term investments

			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
December 31, 2020
Cash equivalents — U.S. Treasury notes	$	72,694	$	1	$	—	$	72,695
Short-term investments — U.S. Treasury notes		209,459		4		(19)		209,444
	$	282,153	$	5	$	(19)	$	282,139

			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
December 31, 2019
Cash equivalents — U.S. Treasury notes	$	10,191	$	1	$	—	$	10,192
Short-term investments — U.S. Treasury notes		186,415		44		(7)		186,452
	$	196,606	$	45	$	(7)	$	196,644