Quarterly report pursuant to Section 13 or 15(d)

Long-Term Debt (Narrative) (Details)

v3.19.2
Long-Term Debt (Narrative) (Details) - USD ($)
 6 Months Ended
Jun. 30, 2019
Mar. 31, 2019
Dec. 31, 2018
Revolving Credit Facility [Member]      
Line Of Credit Facility And Long Term Debt [Line Items]      
Line of credit facility, amount outstanding $ 16,650,000   $ 22,062,000
Credit facility current borrowing capacity $ 60,000,000    
Commitment fee 0.25%    
JPMorgan Chase Bank Credit Agreement [Member]      
Line Of Credit Facility And Long Term Debt [Line Items]      
Additional potential commitments $ 50,000,000    
Credit facility maximum borrowing capacity $ 150,000,000    
Credit facility, Interest rate 4.3055%    
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 current 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 current 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 current 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  
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%