Preferred and Common Stock (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 4 Months Ended 6 Months Ended
Jun. 30, 2019
Mar. 31, 2019
Mar. 21, 2019
Jun. 30, 2018
Mar. 31, 2018
Apr. 18, 2019
Jun. 30, 2019
Jun. 30, 2018
Jul. 15, 2017
Dec. 31, 2018
Preferred stock shares outstanding 25,222           25,222     46,302
Common stock shares outstanding 13,133,806           13,133,806     12,843,414
Shares tendered, nominal value $ 0           $ 0     $ 0
Payments for repurchase of shares             10,009 $ 0    
Percentage of the increase of the preferred dividend rate                 0.25%  
Gain/ (Loss) from stock redemption recognized in Retained Earnings $ 8,703 $ 9,932                
Undeclared preferred dividends             $ 19,048      
Restricted common stock                    
Forfeited shares of common stock 59     150     59 300    
Restricted stock units                    
Vested stock units       0       333    
American Depositary Shares - The Series G                    
Number of shares             2,000,000      
Preferred stock shares outstanding 5,350           5,350     14,191
Sale of Stock- Redemption price per share $ 25           $ 25      
Preferred stock liquidation preference $ 2,500           $ 2,500      
Dividend rate of preferred stock             8.75%      
American Depositary Shares - The Series H                    
Number of shares             4,800,000      
Preferred stock shares outstanding 17,682           17,682     28,612
Sale of Stock- Redemption price per share $ 25           $ 25      
Preferred stock liquidation preference $ 2,500           $ 2,500      
Dividend rate of preferred stock             8.625%      
Convertible preferred stock                    
Conversion of Stock, Shares converted 1,309                  
Preferred stock shares outstanding 2,190           2,190     3,499
Dividends cancelled $ 916                  
Convertible preferred stock | 10 years after the issuance date                    
Sale of Stock- Redemption price per share $ 10           $ 10      
Preferred stock liquidation preference $ 10,000           $ 10,000      
Common Stock                    
Conversion of stock, Shares issued 140,059                  
Stock-based compensation expenses, shares granted   151,515     432,431          
Common Stock | Dividends undeclared                    
Conversion of stock, Shares issued 9,159                  
Price per common unit $ 41           $ 41      
Exchange program for 66 2/3% shares | American Depositary Shares - The Series G                    
Number of shares issued for the exchange offer           8,841        
Shares tendered, nominal value           $ 21,271        
Tender offer expenses           401        
Payments for repurchase of shares           4,423        
2024 Notes issued           3,879        
Gain/ (Loss) from stock redemption recognized in Retained Earnings           12,568        
Dividends cancelled           $ 6,798        
Exchange program for 66 2/3% shares | American Depositary Shares - The Series H                    
Number of shares issued for the exchange offer     10,930              
Shares tendered, nominal value     $ 26,297              
Tender offer expenses     997              
Payments for repurchase of shares     4,188              
2024 Notes issued     4,747              
Gain/ (Loss) from stock redemption recognized in Retained Earnings     16,365              
Dividends cancelled     $ 7,678