Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Preferred Shares (Details)

v3.8.0.1
Summary of Significant Accounting Policies - Preferred Shares (Details)
$ in Thousands
1 Months Ended 12 Months Ended
Mar. 20, 2015
Feb. 23, 2015
shares
May 31, 2015
Sep. 30, 2014
USD ($)
shares
Dec. 31, 2017
USD ($)
Jun. 30, 2015
USD ($)
Preferred shares            
Net consideration         $ 103,167  
Shares exchanged (in shares) | shares   1,758,418        
Share exchange ratio 0.01 0.01        
Deemed dividend, accretion of beneficial conversion feature           $ 14,735
Series A Preferred Shares            
Preferred shares            
Sale of stock (in shares) | shares       1,758,418    
Net consideration       $ 98,872   98,872
Stock issuance costs       $ 4,949    
Conversion ratio, initial rate       1    
Conversion ratio, third anniversary of the issuance       2    
Conversion ratio, initial public offering       1    
Conversion ratio, initial public offering, third anniversary       2    
Deemed dividend, accretion of beneficial conversion feature           $ 14,735
Conversion ratio     1