Annual report pursuant to Section 13 and 15(d)

Subsequent Events - Repurchases of Notes From January 1, 2019 Through Date of Filing (Detail)

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Subsequent Events - Repurchases of Notes From January 1, 2019 Through Date of Filing (Detail) - USD ($)
$ in Thousands
 1 Months Ended 12 Months Ended
Mar. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]      
Cash Paid   $ 16,800 $ 15,400
Principal Repurchased   18,700 16,400
Net Gain   $ 1,700 $ 600
Subsequent Event [Member]      
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]      
Cash Paid $ 3,392    
Principal Repurchased 3,495    
Bond Issue Costs 54    
Net Gain 49    
Subsequent Event [Member] | Senior Secured Note Period One [Member]      
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]      
Cash Paid 2,194    
Principal Repurchased $ 2,250    
Repurchase date Jan. 30, 2020    
Percent face value 97.50%    
Bond Issue Costs $ 35    
Net Gain 22    
Subsequent Event [Member] | Senior Secured Note Period Two [Member]      
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]      
Cash Paid 1,198    
Principal Repurchased $ 1,245    
Repurchase date Jan. 27, 2020    
Percent face value 96.25%    
Bond Issue Costs $ 19    
Net Gain $ 27