Annual report pursuant to Section 13 and 15(d)

Long-Term Debt (Narrative) (Details)

v3.20.1
Long-Term Debt (Narrative) (Details) - USD ($)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Line Of Credit Facility And Long Term Debt [Line Items]    
Percentage of domestic subsidiaries securing credit agreement 100.00%  
Revolving Credit Facility [Member]    
Line Of Credit Facility And Long Term Debt [Line Items]    
Line of credit facility, amount outstanding $ 22,670,000 $ 22,062,000
Credit facility maximum borrowing capacity 60,000,000  
JPMorgan Chase Bank Credit Agreement [Member]    
Line Of Credit Facility And Long Term Debt [Line Items]    
Credit facility maximum borrowing capacity 150,000,000  
Additional potential commitments $ 50,000,000  
Credit facility, Interest rate 3.3125%  
Percentage of foreignsubsidiaries securing credit agreement 65.00%  
JPMorgan Chase Bank Credit Agreement [Member] | Base Rate [Member]    
Line Of Credit Facility And Long Term Debt [Line Items]    
Applicable rate 0.875%  
JPMorgan Chase Bank Credit Agreement [Member] | Eurodollar [Member]    
Line Of Credit Facility And Long Term Debt [Line Items]    
Applicable rate 1.875%  
JPMorgan Chase Bank Credit Agreement [Member] | Revolving Credit Facility [Member]    
Line Of Credit Facility And Long Term Debt [Line Items]    
Credit facility maximum borrowing capacity $ 60,000,000  
JPMorgan Chase Bank Credit Agreement [Member] | Letter Of Credit [Member]    
Line Of Credit Facility And Long Term Debt [Line Items]    
Credit facility maximum borrowing capacity 5,000,000  
JPMorgan Chase Bank Credit Agreement [Member] | Term Facility [Member]    
Line Of Credit Facility And Long Term Debt [Line Items]    
Credit facility maximum borrowing capacity $ 40,000,000  
2018 Credit Agreement [Member]    
Line Of Credit Facility And Long Term Debt [Line Items]    
Credit facility maximum borrowing capacity   $ 75,000,000
Commitment fee   0.25%
Credit facility, Interest rate   3.8493%
2018 Credit Agreement [Member] | LIBOR [Member]    
Line Of Credit Facility And Long Term Debt [Line Items]    
Basis spread on variable rate   1.50%
Minimum [Member] | JPMorgan Chase Bank Credit Agreement [Member]    
Line Of Credit Facility And Long Term Debt [Line Items]    
Commitment fee 0.15%  
Minimum [Member] | JPMorgan Chase Bank Credit Agreement [Member] | Base Rate [Member]    
Line Of Credit Facility And Long Term Debt [Line Items]    
Basis spread on variable rate 0.50%  
Minimum [Member] | JPMorgan Chase Bank Credit Agreement [Member] | Eurodollar [Member]    
Line Of Credit Facility And Long Term Debt [Line Items]    
Basis spread on variable rate 1.50%  
Maximum [Member] | JPMorgan Chase Bank Credit Agreement [Member]    
Line Of Credit Facility And Long Term Debt [Line Items]    
Commitment fee 0.25%  
Maximum [Member] | JPMorgan Chase Bank Credit Agreement [Member] | Base Rate [Member]    
Line Of Credit Facility And Long Term Debt [Line Items]    
Basis spread on variable rate 1.25%  
Maximum [Member] | JPMorgan Chase Bank Credit Agreement [Member] | Eurodollar [Member]    
Line Of Credit Facility And Long Term Debt [Line Items]    
Basis spread on variable rate 2.25%