Quarterly report pursuant to Section 13 or 15(d)

Fair value measurements (Details)

v3.8.0.1
Fair value measurements (Details)
$ in Thousands
Sep. 30, 2017
USD ($)
Marketable securities:  
Corporate debt securities $ 86,532
Recurring basis | Corporate debt securities  
Marketable securities:  
Corporate debt securities 86,532
Recurring basis | Level 1 | Corporate debt securities  
Marketable securities:  
Corporate debt securities 86,532
Recurring basis | Level 3 | Corporate debt securities  
Marketable securities:  
Corporate debt securities $ 0