Annual report pursuant to Section 13 and 15(d)

Mandatorily-Redeemable Preferred Stock - Dividends to Preferred Stockholders (Details)

v3.8.0.1
Mandatorily-Redeemable Preferred Stock - Dividends to Preferred Stockholders (Details) - Series A cumulative term preferred stock - Preferred Stock - $ / shares
Dec. 31, 2017
Dec. 31, 2016
Dividends Payable [Line Items]    
Dividends payable (in dollars per share) $ 1.59375 $ 0.588802083
Dividend Period One    
Dividends Payable [Line Items]    
Dividends payable (in dollars per share) 0.1328125 0.190364583
Dividend Period Two    
Dividends Payable [Line Items]    
Dividends payable (in dollars per share) 0.1328125 0.132812500
Dividend Period Three    
Dividends Payable [Line Items]    
Dividends payable (in dollars per share) 0.1328125 0.132812500
Dividend Period Four    
Dividends Payable [Line Items]    
Dividends payable (in dollars per share) 0.1328125 $ 0.132812500
Dividend Period Five    
Dividends Payable [Line Items]    
Dividends payable (in dollars per share) 0.1328125  
Dividend Period Six    
Dividends Payable [Line Items]    
Dividends payable (in dollars per share) 0.1328125  
Dividend Period Seven    
Dividends Payable [Line Items]    
Dividends payable (in dollars per share) 0.1328125  
Dividend Period Eight    
Dividends Payable [Line Items]    
Dividends payable (in dollars per share) 0.1328125  
Dividend Period Nine    
Dividends Payable [Line Items]    
Dividends payable (in dollars per share) 0.1328125  
Dividend Period Ten    
Dividends Payable [Line Items]    
Dividends payable (in dollars per share) 0.1328125  
Dividend Period Eleven    
Dividends Payable [Line Items]    
Dividends payable (in dollars per share) 0.1328125  
Dividend Period Twelve    
Dividends Payable [Line Items]    
Dividends payable (in dollars per share) $ 0.1328125