Quarterly report pursuant to Section 13 or 15(d)

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

v3.10.0.1
Subsequent Events - Monthly Distributions Declared by Company's Board of Directors (Detail) - $ / shares
Oct. 05, 2018
Sep. 28, 2018
Sep. 25, 2018
Sep. 19, 2018
Aug. 31, 2018
Aug. 21, 2018
Aug. 03, 2018
Jul. 31, 2018
Jul. 24, 2018
Jul. 20, 2018
Aug. 08, 2018
Period One | Subsequent event                      
Subsequent Event [Line Items]                      
Record Date                 Jul. 24, 2018 Jul. 20, 2018  
Payment Date             Aug. 03, 2018 Jul. 31, 2018      
Series A Preferred Stock | Subsequent event                      
Subsequent Event [Line Items]                      
Distributions per share                     $ 0.3984
Series A Preferred Stock | Period One | Subsequent event                      
Subsequent Event [Line Items]                      
Distributions per share               $ 0.1328      
Series B Preferred Stock | Subsequent event                      
Subsequent Event [Line Items]                      
Distributions per share                     0.375
Series B Preferred Stock | Period One | Subsequent event                      
Subsequent Event [Line Items]                      
Distributions per share             $ 0.125        
Common Stock | Subsequent event                      
Subsequent Event [Line Items]                      
Distributions per share                     $ 0.13305
Common Stock | Period One | Subsequent event                      
Subsequent Event [Line Items]                      
Distributions per share               $ 0.04435      
Forecast | Period Two                      
Subsequent Event [Line Items]                      
Record Date           Aug. 21, 2018          
Payment Date         Aug. 31, 2018            
Forecast | Period Three                      
Subsequent Event [Line Items]                      
Record Date     Sep. 25, 2018 Sep. 19, 2018              
Payment Date Oct. 05, 2018 Sep. 28, 2018                  
Forecast | Series A Preferred Stock | Period Two                      
Subsequent Event [Line Items]                      
Distributions per share         $ 0.1328            
Forecast | Series A Preferred Stock | Period Three                      
Subsequent Event [Line Items]                      
Distributions per share   $ 0.1328                  
Forecast | Series B Preferred Stock | Period Two                      
Subsequent Event [Line Items]                      
Distributions per share         0.125            
Forecast | Series B Preferred Stock | Period Three                      
Subsequent Event [Line Items]                      
Distributions per share $ 0.125                    
Forecast | Common Stock | Period Two                      
Subsequent Event [Line Items]                      
Distributions per share         $ 0.04435            
Forecast | Common Stock | Period Three                      
Subsequent Event [Line Items]                      
Distributions per share   $ 0.04435