Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity Preferred Stock Issuances (Details)

v3.10.0.1
Stockholders' Equity Preferred Stock Issuances (Details) - USD ($)
$ / shares in Units, $ in Thousands
1 Months Ended 9 Months Ended 12 Months Ended
Jul. 31, 2018
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
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   $ 13 $ 416,966  
Aggregate cash consideration exchanged for shares of CYS common stock $ 14,967      
Series A Preferred Stock [Member]        
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       $ 138,900
Series A Preferred Stock [Member] | Public Offering [Member]        
Class of Stock [Line Items]        
Number of shares of stock issued during period (in shares)       5,000,000
Series A Preferred Stock [Member] | Over-Allotment Option [Member]        
Class of Stock [Line Items]        
Number of shares of stock issued during period (in shares)       750,000
Series B Preferred Stock [Member]        
Class of Stock [Line Items]        
Number of shares of 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       $ 278,100
Series B Preferred Stock [Member] | Over-Allotment Option [Member]        
Class of Stock [Line Items]        
Number of shares of stock issued during period (in shares)       1,500,000
Series C Preferred Stock [Member]        
Class of Stock [Line Items]        
Preferred stock dividend rate   7.25%    
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   5.011%    
Preferred stock redemption price per share (in usd per share)   $ 25.00    
Proceeds from issuance of preferred stock, net of offering costs       $ 285,600
Series C Preferred Stock [Member] | Public Offering [Member]        
Class of Stock [Line Items]        
Number of shares of stock issued during period (in shares)       11,000,000
Series C Preferred Stock [Member] | Over-Allotment Option [Member]        
Class of Stock [Line Items]        
Number of shares of stock issued during period (in shares)       800,000
Series D Preferred Stock [Member]        
Class of Stock [Line Items]        
Number of shares of stock issued during period (in shares) 3,000,000      
Preferred stock dividend rate   7.75%    
Preferred stock par value per share (in usd per share)   $ 0.01    
Preferred stock liquidation preference per share (in usd per share)   25.00    
Preferred stock redemption price per share (in usd per share)   $ 25.00    
Series E Preferred Stock [Member]        
Class of Stock [Line Items]        
Number of shares of stock issued during period (in shares) 8,000,000      
Preferred stock dividend rate   7.50%    
Preferred stock par value per share (in usd per share)   $ 0.01    
Preferred stock liquidation preference per share (in usd per share)   25.00    
Preferred stock redemption price per share (in usd per share)   $ 25.00