Annual report pursuant to Section 13 and 15(d)

Borrowings - Terms of MetLife Facility (Detail)

v3.20.4
Borrowings - Terms of MetLife Facility (Detail) - MetLife Credit Facility - USD ($)
12 Months Ended
Dec. 31, 2020
Feb. 20, 2020
Dec. 31, 2019
Debt Instrument [Line Items]      
Aggregate Commitment     $ 200,000,000.0
Principal Outstanding $ 37,000,000    
Notes payable to bank      
Debt Instrument [Line Items]      
Aggregate Commitment 75,000,000 $ 75,000,000.0  
Principal Outstanding $ 36,900,000    
Interest rate (as percent) 2.75%    
Undrawn Commitment $ 38,100,000   $ 21,500,000
Notes payable to bank | Minimum      
Debt Instrument [Line Items]      
Unused fee (as percent) 0.10%    
Notes payable to bank | Maximum      
Debt Instrument [Line Items]      
Unused fee (as percent) 0.20%    
Line of credit      
Debt Instrument [Line Items]      
Aggregate Commitment $ 75,000,000    
Principal Outstanding 100,000    
Undrawn Commitment 74,900,000    
Long-term debt, additional amount available $ 24,200,000    
Minimum annualized rate (as percent) 2.50%    
Line of credit | Minimum      
Debt Instrument [Line Items]      
Unused fee (as percent) 0.10%    
Line of credit | Maximum      
Debt Instrument [Line Items]      
Unused fee (as percent) 0.20%    
Line of credit | LIBOR      
Debt Instrument [Line Items]      
Basis spread (as percent) 2.00%