Short-Term Investments

12 Months Ended

Dec. 31, 2021

Investments, Debt and Equity Securities [Abstract]

Short-Term Investments

3. Short-Term Investments

The following tables summarize the amortized cost and estimated fair value of the Company’s marketable securities, which are considered to be available-for-sale investments and were included in short-term investments on the consolidated balance sheets:

	December 31, 2021
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. government treasury securities	$	25,092	$	—	$	(20	)	$	25,072
Marketable securities:
Commercial paper		11,568		1		—			11,569
Corporate bonds		9,821		—		(3	)		9,818
Totals	$	46,481	$	1	$	(23	)	$	46,459
	December 31, 2020
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. government treasury securities	$	233,687	$	—	$	(24	)	$	233,663
Totals	$	233,687	$	—	$	(24	)	$	233,663

Certain short-term debt securities with original maturities of less than three months are included in cash and cash equivalents on the consolidated balance sheets and are not included in the tables above. At December 31, 2021 and 2020, all investments had contractual maturities within one year.