Warrants (Details)
$ / shares in Units, $ in Thousands
 12 Months Ended
Apr. 08, 2013
USD ($)
$ / shares
shares
Apr. 12, 2011
$ / shares
shares
Dec. 31, 2017
item
$ / shares
shares
Dec. 31, 2016
shares
Class of Warrant or Right [Line Items]        
Class of Warrant or Right, Outstanding     9,649,318 9,649,318
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right     0.2857  
Class of Warrant or Right, Number of Securities Called by Warrants or Rights     2,756,810 2,756,810
Class of Warrant or Right, Exercise Price of Warrants or Rights (in Dollars per share) | $ / shares     $ 40.25  
Common Share Price Threshold (in Dollars per share) | $ / shares     $ 61.25  
Number of consecutive trading days in period ending on third business day prior to sending notice of redemption during which the common stock price must equal or exceed threshold price for any 20 trading days     30 days  
Number of shares of common stock that may be issued upon exercise of warrants     2,756,810 2,756,810
Sponsor Warrants        
Class of Warrant or Right [Line Items]        
Class of Warrant or Right, Number of Securities Called by Warrants or Rights   1,142,800    
Warrants Issued During Period, Number   4,000,000    
Price per warrant sold | $ / shares   $ 0.75    
Number of shares of common stock that may be issued upon exercise of warrants   1,142,800    
Public Warrants        
Class of Warrant or Right [Line Items]        
Class of Warrant or Right, Outstanding     4,582,652  
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right     0.2857  
Class of Warrant or Right, Exercise Price of Warrants or Rights (in Dollars per share) | $ / shares     $ 40.25  
Exercise price of warrant if called for redemption | $ / shares     $ 0.01  
Number of days prior written notice required for redemption     30 days  
Number of trading days within a 30 day period the common stock price must equal or exceed threshold price     20 days  
Number of trading days ending on the third trading day prior to the date of notice of redemption over which the average reported last sale price is used as the fair market value     10 days  
Number of warrants exercisable under certain conditions | item     0  
Number of fractional shares of common stock that will be issued upon exercise of warrants | item     0  
Promissory Note        
Class of Warrant or Right [Line Items]        
Aggregate principal amount of the Note | $ $ 800      
Debt Instrument, Convertible, Conversion Price (in Dollars per share) | $ / shares $ 0.75      
Executive Chairman And A Significant Stockholder | Sponsor Warrants        
Class of Warrant or Right [Line Items]        
Class of Warrant or Right, Number of Securities Called by Warrants or Rights 304,746      
Warrants Issued During Period, Number 1,066,666      
Number of shares of common stock that may be issued upon exercise of warrants 304,746      
Executive Chairman        
Class of Warrant or Right [Line Items]        
Aggregate principal amount of the Note | $ $ 400      
Significant Stockholder        
Class of Warrant or Right [Line Items]        
Aggregate principal amount of the Note | $ $ 400