Quarterly report pursuant to Section 13 or 15(d)

Fair value measurements (Details)

v3.19.1
Fair value measurements (Details) - USD ($)
$ in Thousands
Mar. 31, 2019
Dec. 31, 2018
Marketable securities:    
Available-for-sale securities, Debt Securities, Current, Total $ 118,241 $ 136,755
Recurring basis    
Marketable securities:    
Corporate debt securities 109,252  
Agency bond 3,995  
Treasury bills 1,992  
Certificate of deposit 3,002  
Available-for-sale securities, Debt Securities, Current, Total 118,241  
Recurring basis | Level 1    
Marketable securities:    
Corporate debt securities 109,252  
Available-for-sale securities, Debt Securities, Current, Total 109,252  
Recurring basis | Level 2    
Marketable securities:    
Agency bond 3,995  
Treasury bills 1,992  
Certificate of deposit 3,002  
Available-for-sale securities, Debt Securities, Current, Total $ 8,989