Preferred and Common Stock (Details) - USD ($)
$ / shares in Units, $ in Thousands
 2 Months Ended 4 Months Ended 6 Months Ended 9 Months Ended 10 Months Ended 11 Months Ended 12 Months Ended
Feb. 29, 2016
Apr. 19, 2017
Jul. 15, 2017
Sep. 30, 2018
Sep. 30, 2017
Nov. 08, 2016
Dec. 11, 2017
Dec. 11, 2015
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Undeclared preferred dividends       $ 27,372                        
Preferred stock shares outstanding       46,302         46,302 49,504            
Common stock shares outstanding       124,706,280         120,386,472 117,131,407            
Acquisition of treasury stock, value                   $ 818 $ 252          
Value of the exchange offer       $ 12         $ 12 12            
Amount of tender offer paid in cash         $ (485)       (571) (9,323)            
Payments for tender offer expenses       0 485       571 9,323 $ 0          
Shares tendered, nominal value       $ 0         $ 0 $ 0            
Percentage of the increase of the preferred dividend rate     0.25%                          
Dividend rate of preferred stock                 2.00%              
Dividends undeclared                                
Dividends cancelled         $ 702       $ 702              
Restricted common stock                                
Number of common stock issued to employees               2,540,000                
Forfeited shares of common stock       4,500 0       4,232 2,908            
Restricted stock units                                
Vested stock units       3,333 0       843,332 24,970 16,960          
Stock options                                
Exercised number of shares                 0 0 0 143,189 153,556 29,251 130,578 130,577
Restricted stock units granted               1,000,000                
Series G | ADS Exchange Offer                                
Number of shares issued for the exchange offer   360       5,449                    
Amount of tender offer paid in cash   $ 360                            
Series H | ADS Exchange Offer                                
Number of shares issued for the exchange offer   406       18,982                    
Amount of tender offer paid in cash   $ 406                            
Series G and Series H                                
Percentage of the increase of the preferred dividend rate     0.25%                          
Series G and Series H | ADS Exchange Offer                                
Tender offer, stocks           7,589,176                    
Shares exchanged aggregate book value           $ 61,078                    
Payments for tender offer expenses   485       9,323                    
Shares tendered, nominal value   1,914                            
Fair value of stock issued           $ 7,893                    
Shares tendered, value net of fees   1,843                            
Series G and Series H | ADS Exchange Offer | Scenario, Previously Reported [Member]                                
Payments for tender offer expenses   571                            
Shares tendered, nominal value   1,843                            
Series G and Series H | Dividends undeclared | ADS Exchange Offer                                
Dividends cancelled   $ 270                            
American Depositary Shares - The Series G                                
Preferred stock shares outstanding       14,191         14,191 14,551            
Sale of Stock- Redemption price per share       $ 25         $ 25              
Number of shares       2,000,000         2,000,000              
Preferred stock liquidation preference       $ 2,500                        
Preferred Stock, Liquidation Preference Per Share                 $ 2,500              
Dividend rate of preferred stock       8.75%         8.75%              
Preferred Stock Redemption Terms                 Each of the shares represents 1/100th of a share of the Series G, with a liquidation preference of $2,500.00 per share ($25.00 per American Depositary Share). Dividends are payable quarterly in arrears on the Series G at a rate of 8.75% per annum and on the Series H at a rate of 8.625% per annum of the stated liquidation preference. At any time on or after January 28, 2019, the Series G may be redeemed at the Company's option and at any time on or after July 8, 2019, the Series H may be redeemed at the Company's option (and the American Depositary Shares can be caused to be redeemed), in whole or in part, out of amounts legally available therefore, at a redemption price of $2,500.00 per share (equivalent to $25.00 per American Depositary Share) plus an amount equal to all accumulated and unpaid dividends thereon to the date of redemption, whether or not declared. The Company has accounted for these shares as equity.              
American Depositary Shares - The Series H                                
Preferred stock shares outstanding       28,612         28,612 29,018            
Sale of Stock- Redemption price per share       $ 25         $ 25              
Number of shares       4,800,000         4,800,000              
Preferred stock liquidation preference       $ 2,500                        
Preferred Stock, Liquidation Preference Per Share                 $ 2,500              
Dividend rate of preferred stock       8.625%         8.625%              
Preferred Stock Redemption Terms                 Each of the shares represents 1/100th of a share of the Series G, with a liquidation preference of $2,500.00 per share ($25.00 per American Depositary Share). Dividends are payable quarterly in arrears on the Series G at a rate of 8.75% per annum and on the Series H at a rate of 8.625% per annum of the stated liquidation preference. At any time on or after January 28, 2019, the Series G may be redeemed at the Company's option and at any time on or after July 8, 2019, the Series H may be redeemed at the Company's option (and the American Depositary Shares can be caused to be redeemed), in whole or in part, out of amounts legally available therefore, at a redemption price of $2,500.00 per share (equivalent to $25.00 per American Depositary Share) plus an amount equal to all accumulated and unpaid dividends thereon to the date of redemption, whether or not declared. The Company has accounted for these shares as equity.              
Convertible preferred stock                                
Conversion of Stock, Shares converted         (2,436)       2,436              
Preferred stock shares outstanding       3,499         3,499 5,935            
Sale of Stock- Redemption price per share                 $ 14              
Preferred stock liquidation preference         $ 10,000       $ 10,000              
Preferred Stock, Liquidation Preference Per Share         $ 14                      
Common Stock                                
Number of common stock issued to employees             4,320,975                  
Converted Shares of Common Stock         1,740,000       1,790,150   1,134,000          
Acquisition of treasury stock, shares                   948,584 199,324          
Amount of tender offer paid in cash                   $ 1            
Tender offer, stocks         625,815       625,815 7,589,176            
Conversion of undeclared preferred dividend to common stock         50,150                      
Common Stock | ADS Exchange Offer                                
Restricted stock units granted             4,320,975                  
Tender offer, stocks   625,815                            
Fair value of stock issued   $ 1,127                            
Common Stock | First conversion                                
Converted Shares of Common Stock         1,740,000       1,740,000              
Common Stock | Second conversion                                
Converted Shares of Common Stock                 50,150              
Fair value of stock issued         $ 84       $ 84              
Conversion of undeclared preferred dividend to common stock         50,150                      
Common Stock | Share Repurchase Program                                
Share repurchase program, Authorized amount                 $ 25,000              
Acquisition of treasury stock, shares 1,147,908                 948,584            
Acquisition of treasury stock, value $ 1,070                 $ 818            
Preferred Stock                                
Conversion of Stock, Shares converted         2,436       2,436   1,134          
Number of shares issued for the exchange offer         766       766 24,431            
Preferred Stock | Dividends undeclared                                
Undeclared preferred dividends                 $ 19,693              
Dividends cancelled                 $ 972