Quarterly report pursuant to Section 13 or 15(d)

Equity Preferred Stock (Details)

v3.8.0.1
Equity Preferred Stock (Details) - USD ($)
$ / shares in Units, $ in Thousands
 1 Months Ended 9 Months Ended
Jul. 19, 2017
Sep. 30, 2017
Sep. 30, 2016
Dec. 31, 2016
Class of Stock [Line Items]        
Preferred stock par value per share (in usd per share)   $ 0.01   $ 0.01
Proceeds from issuance of preferred stock, net of offering costs   $ 416,966 $ 0  
Series A Preferred Stock        
Class of Stock [Line Items]        
Preferred stock dividend rate   8.125%    
Preferred stock par value per share (in usd per share)   $ 0.01    
Preferred stock public offering price per share (in usd per share)   25.00    
Preferred stock liquidation preference per share (in usd per share)   $ 25.00    
Preferred stock dividend variable rate spread   5.66%    
Preferred stock redemption price per share (in usd per share)   $ 25.00    
Proceeds from issuance of preferred stock, net of offering costs   $ 138,872    
Series A Preferred Stock | Public Offering [Member]        
Class of Stock [Line Items]        
Number of shares of preferred stock issued during period (in shares)   5,000,000    
Series A Preferred Stock | Over-Allotment Option [Member]        
Class of Stock [Line Items]        
Number of shares of preferred stock issued during period (in shares)   750,000    
Series B Preferred Stock        
Class of Stock [Line Items]        
Number of shares of preferred stock issued during period (in shares)   11,500,000    
Preferred stock dividend rate 7.625%      
Preferred stock par value per share (in usd per share) $ 0.01      
Preferred stock public offering price per share (in usd per share) 25.00      
Preferred stock liquidation preference per share (in usd per share) $ 25.00      
Preferred stock dividend variable rate spread 5.352%      
Preferred stock redemption price per share (in usd per share) $ 25.00      
Proceeds from issuance of preferred stock, net of offering costs $ 278,094      
Series B Preferred Stock | Over-Allotment Option [Member]        
Class of Stock [Line Items]        
Number of shares of preferred stock issued during period (in shares) 1,500,000