Annual report pursuant to Section 13 and 15(d)

Stockholders' equity - Ordinary Shares (Details)

v3.8.0.1
Stockholders' equity - Ordinary Shares (Details)
Jun. 21, 2017
GBP (£)
Dec. 31, 2017
Jun. 21, 2017
USD ($)
Stockholders' equity      
Number of votes per share on a show of hands   1  
Number of votes per share on a poll   1  
Maximum aggregate nominal amount | £ £ 140,000    
Period of authority for directors 5 years    
Maximum aggregate nominal amount of shares without offering to existing shareholders holding proportion | $     $ 140,000