Quarterly report pursuant to Section 13 or 15(d)

Cash and cash equivalents (Details)

v3.10.0.1
Cash and cash equivalents (Details) - USD ($)
$ in Thousands
Sep. 30, 2018
Dec. 31, 2017
Sep. 30, 2017
Dec. 31, 2016
Cash, Cash Equivalents, and Short-term Investments [Abstract]        
Cash and cash equivalents $ 45,647 $ 136,986 $ 117,787 $ 82,387