Quarterly report pursuant to Section 13 or 15(d)

Line of Credit (Details)

v3.8.0.1
Line of Credit (Details)
Jun. 09, 2017
Apr. 01, 2018
USD ($)
Mar. 31, 2018
USD ($)
Feb. 26, 2018
USD ($)
Dec. 31, 2017
USD ($)
Line of Credit Facility [Line Items]          
Revolving credit facility     $ 40,000,000    
Outstanding borrowings under our Credit Agreement     $ 10,000,000   $ 0
Interest rate     3.75%    
Total outstanding letters of credit     $ 2,500,000    
Remaining borrowing capacity on line of credit     $ 27,500,000    
Financial covenants, minimum current assets to current liabilities ratio     1.25    
Financial covenants, minimum net worth       $ 185,000,000  
Financial covenants, percent of net income added to net worth requirement     50.00%    
Financial covenants, percent of gain on sale of assets added to net worth requirement       50.00%  
Financial covenants, percent of proceeds from stock issuance added to net worth requirement     100.00%    
Financial covenant, maximum funded debt to tangible net worth ratio     0.5    
Letter of Credit          
Line of Credit Facility [Line Items]          
Stated interest rate 2.00%        
Revolving Credit Facility          
Line of Credit Facility [Line Items]          
Fees on undrawn borrowings 0.40%        
London Interbank Offered Rate (LIBOR) | Letter of Credit          
Line of Credit Facility [Line Items]          
Basis spread on variable rate 2.00%        
Letter of Credit | Subsequent Event          
Line of Credit Facility [Line Items]          
Letters of credit reissued   $ 3,000,000