Annual report pursuant to Section 13 and 15(d)

CREDIT FACILITIES (Details)

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CREDIT FACILITIES (Details)
12 Months Ended
Aug. 27, 2018
USD ($)
Dec. 31, 2018
USD ($)
Line of Credit Facility [Line Items]    
Revolving credit facility $ 40,000,000.0  
Financial covenants, minimum current ratio 1.25 2.85
Financial covenants, minimum net worth $ 180,000,000.0  
Financial covenants, percent of proceeds from stock issuance added to net worth requirement 100.00%  
Financial covenants, maximum funded debt to tangible net worth ratio 0.50 0.01
Borrowings under credit agreement   $ 0
Outstanding letters of credit   2,900,000
Revolving credit facility, unused portion   37,100,000
Tangible net worth   199,200,000
Surety bonds   $ 396,600,000
Letter of Credit    
Line of Credit Facility [Line Items]    
Stated interest rate 2.00%  
Letter of Credit | Prime Rate    
Line of Credit Facility [Line Items]    
Basis spread on variable interest rate   5.50%
Letter of Credit | London Interbank Offered Rate (LIBOR)    
Line of Credit Facility [Line Items]    
Basis spread on variable interest rate 2.00% 2.52%
Revolving Credit Facility    
Line of Credit Facility [Line Items]    
Fees on unused borrowings 0.40%