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Short-term investments (Tables)
9 Months Ended
Sep. 30, 2021
Short-term investments  
Schedule of short-term investments by investment type

Short-term investments by investment type consisted of the following (in thousands):

    

December 31, 2020

Gross

Gross

 

Amortized

 

unrealized

 

unrealized

 

Fair

    

 cost

    

gains

    

losses

    

value

U.S. Treasury bonds

$

14,997

$

1

$

$

14,998

$

14,997

$

1

$

$

14,998