Quarterly report pursuant to Section 13 or 15(d)

Long-Term Debt (Narrative) (Details)

v3.10.0.1
Long-Term Debt (Narrative) (Details) - USD ($)
Jun. 27, 2018
Jun. 30, 2018
Dec. 31, 2017
Revolving Credit Facility [Member]      
Line Of Credit Facility And Long Term Debt [Line Items]      
Line of credit facility, amount outstanding   $ 16,000,000 $ 20,842,000
Zions First National Bank [Member] | Terminated Credit Agreement [Member]      
Line Of Credit Facility And Long Term Debt [Line Items]      
Credit facility maximum borrowing capacity $ 40,000,000    
Payments to reduce outstanding balance of line of credit 16,199,000    
JPMorgan Chase Bank, N.A. [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, N.A. [Member] | Revolving Credit Facility [Member]      
Line Of Credit Facility And Long Term Debt [Line Items]      
Credit facility maximum borrowing capacity 75,000,000    
Credit facility, conditional commitments 75,000,000    
Credit facility maximum borrowing capacity after conditional commitments $ 150,000,000    
Initial interest rate 1.50%    
JPMorgan Chase Bank, N.A. [Member] | Revolving Credit Facility [Member] | LIBOR [Member]      
Line Of Credit Facility And Long Term Debt [Line Items]      
Interest rate floor 0.00%    
JPMorgan Chase Bank, N.A. [Member] | Revolving Credit Facility [Member] | Eurodollar [Member]      
Line Of Credit Facility And Long Term Debt [Line Items]      
Interest rate floor 0.00%    
Minimum [Member] | JPMorgan Chase Bank, N.A. [Member] | Revolving Credit Facility [Member]      
Line Of Credit Facility And Long Term Debt [Line Items]      
Unused commitment fee percentage 0.25%    
Minimum [Member] | JPMorgan Chase Bank, N.A. [Member] | Revolving Credit Facility [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, N.A. [Member] | Revolving Credit Facility [Member]      
Line Of Credit Facility And Long Term Debt [Line Items]      
Unused commitment fee percentage 0.375%    
Maximum [Member] | JPMorgan Chase Bank, N.A. [Member] | Revolving Credit Facility [Member] | Eurodollar [Member]      
Line Of Credit Facility And Long Term Debt [Line Items]      
Basis spread on variable rate 2.20%