Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2021

Investments All Other Investments [Abstract]

Cash Equivalents, Restricted Cash and Short-Term Investments Classified as Available-for-sale Securities

Cash equivalents and investments (debt securities) which are classified as available-for-sale securities, consisted of the following (in thousands):

June 30, 2021	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Money market funds (cash equivalents)	$	73,621	$	—	$	—	$	73,621
U.S. government agency securities		7,778		1		—		7,779
Federal agency securities		5,122		1		—		5,123
Total financial assets	$	86,521	$	2	$	—	$	86,523
Classified as:
Cash and cash equivalents							$	73,621
Short-term investments								12,902
Total financial assets							$	86,523

December 31, 2020	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Money market funds (cash equivalents)	$	30,360	$	—	$	—	$	30,360
U.S. government agency securities		37,835		2		—		37,837
Federal agency securities		13,697		3		—		13,700
Total financial assets	$	81,892	$	5	$	—	$	81,897
Classified as:
Cash and cash equivalents							$	30,360
Short-term investments								48,994
Long-term investments								2,543
Total financial assets							$	81,897