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Marketable Securities and Fair Value Measurements - Securities in Unrealized Loss Position (Details) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Fair Value    
Less Than 12 Months $ 20,355 $ 2,996
12 Months or More 0 0
Total 20,355 2,996
Gross Unrealized Losses    
Less Than 12 Months (8) (1)
12 Months or More 0 0
Total (8) (1)
Certificates of deposit    
Fair Value    
Less Than 12 Months 0 0
12 Months or More 0 0
Total 0 0
Gross Unrealized Losses    
Less Than 12 Months 0 0
12 Months or More 0 0
Total 0 0
Corporate securities    
Fair Value    
Less Than 12 Months 20,355 2,996
12 Months or More 0 0
Total 20,355 2,996
Gross Unrealized Losses    
Less Than 12 Months (8) (1)
12 Months or More 0 0
Total (8) (1)
U.S. Treasury and agency securities    
Fair Value    
Less Than 12 Months 0 0
12 Months or More 0 0
Total 0 0
Gross Unrealized Losses    
Less Than 12 Months 0 0
12 Months or More 0 0
Total 0 0
Commercial paper    
Fair Value    
Less Than 12 Months 0 0
12 Months or More 0 0
Total 0 0
Gross Unrealized Losses    
Less Than 12 Months 0 0
12 Months or More 0 0
Total 0 0
Asset-backed securities    
Fair Value    
Less Than 12 Months 0 0
12 Months or More 0 0
Total 0 0
Gross Unrealized Losses    
Less Than 12 Months 0 0
12 Months or More 0 0
Total $ 0 $ 0