Annual report pursuant to Section 13 and 15(d)

Income taxes - Income before Income Taxes (Details)

v3.10.0.1
Income taxes - Income before Income Taxes (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Income taxes      
Loss before income taxes $ (95,017) $ (69,687) $ (70,687)
U.S.      
Income taxes      
Loss before income taxes (1,650) (3,121) (3,373)
U.K.      
Income taxes      
Loss before income taxes $ (93,367) $ (66,566) $ (67,314)