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Credit Facility - Additional Information (Detail) - USD ($)
Feb. 16, 2018
Dec. 31, 2019
Feb. 27, 2018
Line of Credit Facility [Line Items]      
Line of credit, available borrowings     $ 200,000,000.0
Current borrowing capacity     $ 50,000,000.0
Long-term Line of Credit   $ 0  
Base rate      
Line of Credit Facility [Line Items]      
Basis spread on variable rate 0.50%    
Base rate | Minimum      
Line of Credit Facility [Line Items]      
Basis spread on variable rate 0.25%    
Base rate | Maximum      
Line of Credit Facility [Line Items]      
Basis spread on variable rate 0.75%    
LIBOR rate      
Line of Credit Facility [Line Items]      
Basis spread on variable rate 1.00%    
LIBOR rate | Minimum      
Line of Credit Facility [Line Items]      
Basis spread on variable rate 1.25%    
LIBOR rate | Maximum      
Line of Credit Facility [Line Items]      
Basis spread on variable rate 1.75%