v3.19.3.a.u2
Equity - Additional Information (Detail) - $ / shares
12 Months Ended
Jan. 10, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Equity [Line Items]        
Capital stock, shares authorized   100,000,000    
Common stock, shares authorized   80,000,000 80,000,000  
Common stock, par value   $ 0.001 $ 0.001  
Preferred stock, shares authorized   20,000,000 20,000,000  
Preferred stock, par value   $ 0.001 $ 0.001  
Common stock, voting rights   one vote per share    
Preferred stock, shares issued   0 0  
Preferred stock, shares outstanding   0 0  
Description of total shares quarterly redeemed   Total shares redeemed pursuant to the Share Redemption Program in any quarter could not exceed 1% of the total number of shares outstanding at the beginning of the calendar year plus 50% of the total number of any additional shares issued during the prior calendar quarter under the DRIP (as defined below), provided that the total number of shares redeemed during any calendar year could not exceed 5% of the number of shares outstanding as of the first day of such calendar year    
Common stock, shares issued   26,001,000 22,014,000  
Distribution Reinvestment Plan        
Equity [Line Items]        
Percentage of shares in value offered   98.00%    
Common stock, shares issued   3,005,000 2,233,000 1,592,000
Subsequent Event        
Equity [Line Items]        
Share redemption program termination effective date Feb. 10, 2020      
Stock Redeemable After 12 Months but Less than Five Years        
Equity [Line Items]        
Share value redeemable percentage   95.00%    
Stock Redeemable after Five Years        
Equity [Line Items]        
Share value redeemable percentage   100.00%