Preferred and Common Stock (Details) - USD ($)
2 Months Ended 4 Months Ended 6 Months Ended
Feb. 29, 2016
Apr. 19, 2017
Jun. 30, 2017
Jun. 30, 2016
Dec. 31, 2016
Preferred stock shares outstanding     46,302   49,504
Common stock shares outstanding     119,497,222   117,131,407
Undeclared preferred dividends     $ 15,279,000    
Acquisition of treasury stock, value       $ 819,000  
Shared tendered, nominal value     0   $ 0
Payments for tender offer expenses     482,000 $ 0  
Value of common stock     $ 12,000   $ 12,000
Restricted common stock          
Forfeited shares of common stock     0 2,850  
Restricted stock units          
Vested stock units     0 21,301  
Series G and Series H          
Shared tendered, nominal value   $ 1,914,000      
American Depositary Shares - The Series G          
Preferred stock shares outstanding     14,191   14,551
Sale of Stock- Redemption price per share     $ 25    
Depositary Shares     2,000,000    
Dividend rate of preferred stock     8.75%    
Preferred stock liquidation preference     $ 2,500    
Shares validly tendered   360      
American Depositary Shares - The Series H          
Preferred stock shares outstanding     28,612   29,018
Sale of Stock- Redemption price per share     $ 25    
Depositary Shares     4,800,000    
Dividend rate of preferred stock     8.625%    
Preferred stock liquidation preference     $ 2,500    
Shares validly tendered   406      
Convertible preferred stock          
Conversion of Stock, Shares converted     2,436    
Preferred stock shares outstanding     3,499   5,935
Sale of Stock- Redemption price per share     $ 14    
Preferred stock liquidation preference     $ 10,000    
Common Stock          
Converted Shares of Common Stock     1,740,000    
Acquisition of treasury stock, shares       948,584  
Common stock issued   625,815 625,815    
Preferred Stock          
Conversion of Stock, Shares converted     (2,436)    
Shares validly tendered     (766)    
Undeclared preferred dividends     $ 15,279,000    
Share Repurchase Program | Common Stock          
Share repurchase program, Authorized amount     $ 25,000,000    
Acquisition of treasury stock, shares 1,147,908        
Acquisition of treasury stock, value $ 1,071,000