Annual report pursuant to Section 13 and 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
12 Months Ended
Dec. 31, 2018
Mar. 26, 2019
Mar. 20, 2019
Feb. 26, 2019
Feb. 20, 2019
Jan. 23, 2019
Jan. 18, 2019
Jan. 08, 2019
Series A Preferred Stock | Period One                
Subsequent Event [Line Items]                
Record Date Jan. 18, 2019              
Payment Date Jan. 31, 2019              
Series A Preferred Stock | Period Two                
Subsequent Event [Line Items]                
Record Date Feb. 20, 2019              
Payment Date Feb. 28, 2019              
Series A Preferred Stock | Period Three                
Subsequent Event [Line Items]                
Record Date Mar. 20, 2019              
Payment Date Mar. 29, 2019              
Series B Preferred Stock | Period One                
Subsequent Event [Line Items]                
Record Date Jan. 23, 2019              
Payment Date Feb. 01, 2019              
Series B Preferred Stock | Period Two                
Subsequent Event [Line Items]                
Record Date Feb. 26, 2019              
Payment Date Mar. 07, 2019              
Series B Preferred Stock | Period Three                
Subsequent Event [Line Items]                
Record Date Mar. 26, 2019              
Payment Date Apr. 04, 2019              
Common Stock | Period One                
Subsequent Event [Line Items]                
Record Date Jan. 18, 2019              
Payment Date Jan. 31, 2019              
Common Stock | Period Two                
Subsequent Event [Line Items]                
Record Date Feb. 20, 2019              
Payment Date Feb. 28, 2019              
Common Stock | Period Three                
Subsequent Event [Line Items]                
Record Date Mar. 20, 2019              
Payment Date Mar. 29, 2019              
Subsequent Event | Series A Preferred Stock                
Subsequent Event [Line Items]                
Distribution per Share               $ 0.3984375
Subsequent Event | Series A Preferred Stock | Period One                
Subsequent Event [Line Items]                
Distribution per Share             $ 0.1328125  
Subsequent Event | Series B Preferred Stock                
Subsequent Event [Line Items]                
Distribution per Share               0.375
Subsequent Event | Series B Preferred Stock | Period One                
Subsequent Event [Line Items]                
Distribution per Share           $ 0.125    
Subsequent Event | Common Stock                
Subsequent Event [Line Items]                
Distribution per Share               $ 0.13335
Subsequent Event | Common Stock | Period One                
Subsequent Event [Line Items]                
Distribution per Share             $ 0.04445  
Forecast | Series A Preferred Stock | Period Two                
Subsequent Event [Line Items]                
Distribution per Share         $ 0.1328125      
Forecast | Series A Preferred Stock | Period Three                
Subsequent Event [Line Items]                
Distribution per Share     $ 0.1328125          
Forecast | Series B Preferred Stock | Period Two                
Subsequent Event [Line Items]                
Distribution per Share       $ 0.125        
Forecast | Series B Preferred Stock | Period Three                
Subsequent Event [Line Items]                
Distribution per Share   $ 0.125            
Forecast | Common Stock | Period Two                
Subsequent Event [Line Items]                
Distribution per Share         $ 0.04445      
Forecast | Common Stock | Period Three                
Subsequent Event [Line Items]                
Distribution per Share     $ 0.04445