Annual report pursuant to Section 13 and 15(d)

FAIR VALUE (Details)

v3.20.4
FAIR VALUE (Details) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Fair Value    
Investments at fair value $ 35,852 $ 87,250
U.S. treasury bills    
Fair Value    
Investments at fair value 10,034 12,539
Government-sponsored enterprises securities    
Fair Value    
Investments at fair value 4,920 19,017
Corporate bonds and commercial paper    
Fair Value    
Investments at fair value 20,898 55,694
Fair value measurements recurring | Estimate Of Fair Value Fair Value Disclosure    
Fair Value    
Investments at fair value 55,339 94,707
Fair value measurements recurring | Money market funds | Estimate Of Fair Value Fair Value Disclosure    
Fair Value    
Investments at fair value 19,487 7,457
Fair value measurements recurring | U.S. treasury bills | Estimate Of Fair Value Fair Value Disclosure    
Fair Value    
Investments at fair value 10,034 12,539
Fair value measurements recurring | Government-sponsored enterprises securities | Estimate Of Fair Value Fair Value Disclosure    
Fair Value    
Investments at fair value 4,920 19,017
Fair value measurements recurring | Corporate bonds and commercial paper | Estimate Of Fair Value Fair Value Disclosure    
Fair Value    
Investments at fair value 20,898 55,694
Fair value measurements recurring | Fair value inputs Level 1    
Fair Value    
Investments at fair value 19,487 7,457
Fair value measurements recurring | Fair value inputs Level 1 | Money market funds    
Fair Value    
Investments at fair value 19,487 7,457
Fair value measurements recurring | Fair value inputs Level 2    
Fair Value    
Investments at fair value 35,852 87,250
Fair value measurements recurring | Fair value inputs Level 2 | U.S. treasury bills    
Fair Value    
Investments at fair value 10,034 12,539
Fair value measurements recurring | Fair value inputs Level 2 | Government-sponsored enterprises securities    
Fair Value    
Investments at fair value 4,920 19,017
Fair value measurements recurring | Fair value inputs Level 2 | Corporate bonds and commercial paper    
Fair Value    
Investments at fair value $ 20,898 $ 55,694