Results for the year - Range of exercise (Details)
EquityInstruments in Thousands
12 Months Ended
Dec. 31, 2017
USD ($)
EquityInstruments
Dec. 31, 2016
USD ($)
EquityInstruments
Dec. 31, 2015
USD ($)
EquityInstruments
Nov. 30, 2017
DKK (kr)
Nov. 30, 2017
USD ($)
Disclosure of range of exercise prices of outstanding share options [line items]          
Exercise price | kr       kr 0.01  
Outstanding equity awards | EquityInstruments 14,191 46,895 42,545    
Dividend yield (%) 0 0 0    
Average fair value per option or warrant granted ($) $ 10.90 $ 1.18 $ 1.31    
Minimum          
Disclosure of range of exercise prices of outstanding share options [line items]          
Exercise price $ 0.0016 $ 0.06 $ 0.06   $ 0.0016
Expected volatility (%) 64 73 69    
Risk-free interest rate (%) (0.7) (1.2) (0.1)    
Expected life of the equity award (years) 6 months 4 years 3 years 6 months    
Share price $ 2.04 $ 1.64 $ 1.81    
Maximum          
Disclosure of range of exercise prices of outstanding share options [line items]          
Exercise price $ 6.92 $ 2.20 $ 3.69   $ 14.13
Expected volatility (%) 79 79 76    
Risk-free interest rate (%) 2.1 1.8 1.7    
Expected life of the equity award (years) 7 years 5 years 5 years    
Share price $ 2.74 $ 2.20 $ 3.90    
$0.0016 to $0.12          
Disclosure of range of exercise prices of outstanding share options [line items]          
Outstanding equity awards | EquityInstruments 7,625 17,878 20,069    
$0.0016 to $0.12 | Minimum          
Disclosure of range of exercise prices of outstanding share options [line items]          
Exercise price $ 0.0016        
$0.0016 to $0.12 | Maximum          
Disclosure of range of exercise prices of outstanding share options [line items]          
Exercise price 0.12        
$0.75 to $0.95          
Disclosure of range of exercise prices of outstanding share options [line items]          
Outstanding equity awards | EquityInstruments   2,139 2,139    
$0.75 to $0.95 | Minimum          
Disclosure of range of exercise prices of outstanding share options [line items]          
Exercise price 0.75        
$0.75 to $0.95 | Maximum          
Disclosure of range of exercise prices of outstanding share options [line items]          
Exercise price $ 0.95        
$1.26 to $1.80          
Disclosure of range of exercise prices of outstanding share options [line items]          
Outstanding equity awards | EquityInstruments 179 4,635      
$1.26 to $1.80 | Minimum          
Disclosure of range of exercise prices of outstanding share options [line items]          
Exercise price $ 1.26        
$1.26 to $1.80 | Maximum          
Disclosure of range of exercise prices of outstanding share options [line items]          
Exercise price $ 1.80        
$2.09 to $2.83          
Disclosure of range of exercise prices of outstanding share options [line items]          
Outstanding equity awards | EquityInstruments 2,618 13,037 11,037    
$2.09 to $2.83 | Minimum          
Disclosure of range of exercise prices of outstanding share options [line items]          
Exercise price $ 2.09        
$2.09 to $2.83 | Maximum          
Disclosure of range of exercise prices of outstanding share options [line items]          
Exercise price $ 2.83        
$3.05 to $3.77          
Disclosure of range of exercise prices of outstanding share options [line items]          
Outstanding equity awards | EquityInstruments 674 6,708 6,802    
$3.05 to $3.77 | Minimum          
Disclosure of range of exercise prices of outstanding share options [line items]          
Exercise price $ 3.05        
$3.05 to $3.77 | Maximum          
Disclosure of range of exercise prices of outstanding share options [line items]          
Exercise price $ 3.77        
$4.51 to $6.92          
Disclosure of range of exercise prices of outstanding share options [line items]          
Outstanding equity awards | EquityInstruments 597        
$4.51 to $6.92 | Minimum          
Disclosure of range of exercise prices of outstanding share options [line items]          
Exercise price $ 4.51        
$4.51 to $6.92 | Maximum          
Disclosure of range of exercise prices of outstanding share options [line items]          
Exercise price 6.92        
$14.13          
Disclosure of range of exercise prices of outstanding share options [line items]          
Exercise price $ 14.13        
Outstanding equity awards | EquityInstruments 2,498 2,498 2,498