Short-Term Investments

3 Months Ended

Mar. 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 condensed consolidated balance sheets:

	March 31, 2021
(in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
U.S. government treasury securities		168,329		18		—		168,347
Totals	$	168,329	$	18	$	—	$	168,347

	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	$	0	$	(24	)	$	233,663

Certain short-term debt securities with original maturities of less than 90 days are included in cash and cash equivalents on the condensed consolidated balance sheets and are not included in the tables above. At March 31, 2021 and December 31, 2020, all investments had contractual maturities within one year.