Annual report pursuant to Section 13 and 15(d)

Bank Loans (Narrative) (Details)

v3.20.4
Bank Loans (Narrative) (Details) - Wells Fargo Credit Facility [Member] - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Line of Credit Facility [Line Items]    
Line of credit, borrowing limit $ 250,000  
Line of credit, expiration date Jan. 10, 2022  
Spread over LIBOR 0.825%  
Line of credit, facility fee percent 0.125%  
Credit facility, outstanding $ 0 $ 0
Unamortized loan origination costs $ 200 $ 500
Line of credit, frequency of interest payment monthly  
Maximum [Member]    
Line of Credit Facility [Line Items]    
Spread over LIBOR 1.55%  
Line of credit, facility fee percent 0.30%  
Minimum [Member]    
Line of Credit Facility [Line Items]    
Spread over LIBOR 0.80%  
Line of credit, facility fee percent 0.10%