Annual report pursuant to Section 13 and 15(d)

Subsequent Events - Monthly Distributions Declared by Company's Board of Directors (Detail)

v3.8.0.1
Subsequent Events - Monthly Distributions Declared by Company's Board of Directors (Detail) - $ / shares
Mar. 30, 2018
Mar. 20, 2018
Feb. 28, 2018
Feb. 16, 2018
Jan. 31, 2018
Jan. 22, 2018
Jan. 09, 2018
Dec. 31, 2017
Dec. 31, 2016
Dividends per preferred share | Dividends per Series A Term Preferred Share                  
Subsequent Event [Line Items]                  
Distributions (in dollars per share)               $ 1.59375 $ 0.588802083
Dividends per preferred share | Dividends per Series A Term Preferred Share | Dividend Period One                  
Subsequent Event [Line Items]                  
Distributions (in dollars per share)               0.1328125 0.190364583
Dividends per preferred share | Dividends per Series A Term Preferred Share | Dividend Period Two                  
Subsequent Event [Line Items]                  
Distributions (in dollars per share)               0.1328125 0.132812500
Dividends per preferred share | Dividends per Series A Term Preferred Share | Dividend Period Three                  
Subsequent Event [Line Items]                  
Distributions (in dollars per share)               $ 0.1328125 $ 0.132812500
Subsequent Event | Dividend Period One                  
Subsequent Event [Line Items]                  
Record Date           Jan. 22, 2018      
Payment Date         Jan. 31, 2018        
Subsequent Event | Dividend Period Two                  
Subsequent Event [Line Items]                  
Record Date       Feb. 16, 2018          
Subsequent Event | Distribution per Common Share                  
Subsequent Event [Line Items]                  
Distributions (in dollars per share)             $ 0.13275    
Subsequent Event | Distribution per Common Share | Dividend Period One                  
Subsequent Event [Line Items]                  
Distributions (in dollars per share)         $ 0.04425        
Subsequent Event | Dividends per preferred share | Dividends per Series A Term Preferred Share                  
Subsequent Event [Line Items]                  
Distributions (in dollars per share)             $ 0.3984375    
Subsequent Event | Dividends per preferred share | Dividends per Series A Term Preferred Share | Dividend Period One                  
Subsequent Event [Line Items]                  
Distributions (in dollars per share)         $ 0.1328125        
Forecast | Dividend Period Two                  
Subsequent Event [Line Items]                  
Payment Date     Feb. 28, 2018            
Forecast | Dividend Period Three                  
Subsequent Event [Line Items]                  
Record Date   Mar. 20, 2018              
Payment Date Mar. 30, 2018                
Forecast | Distribution per Common Share | Dividend Period Two                  
Subsequent Event [Line Items]                  
Distributions (in dollars per share)     $ 0.04425            
Forecast | Distribution per Common Share | Dividend Period Three                  
Subsequent Event [Line Items]                  
Distributions (in dollars per share) $ 0.04425                
Forecast | Dividends per preferred share | Dividends per Series A Term Preferred Share | Dividend Period Two                  
Subsequent Event [Line Items]                  
Distributions (in dollars per share)     $ 0.1328125            
Forecast | Dividends per preferred share | Dividends per Series A Term Preferred Share | Dividend Period Three                  
Subsequent Event [Line Items]                  
Distributions (in dollars per share) $ 0.1328125