Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2021

Investments All Other Investments [Abstract]

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

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

March 31, 2021	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Money market funds (cash equivalents)	$	83,044	$	—	$	—	$	83,044
U.S. government agency securities		16,804		3		—		16,807
Federal agency securities		7,147		2		—		7,149
Total financial assets	$	106,995	$	5	$	—	$	107,000
Classified as:
Cash and cash equivalents							$	83,044
Short-term investments								23,956
							$	107,000

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
							$	81,897