v3.19.1
DEBT (Narrative) (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Oct. 31, 2018
USD ($)
Sep. 30, 2018
USD ($)
Oct. 31, 2017
Debt Instrument [Line Items]            
Proceeds from from short-term borrowings on credit facility $ 13,500 $ 22,000        
Repayments of short-term borrowings on credit facility 17,400 18,100        
Interest costs incurred 3,983 11,822 $ 12,071      
Senior Notes [Member]            
Debt Instrument [Line Items]            
Senior notes $ 50,000 60,000        
Fixed charge coverage ratio 12.0          
Leverage ratio 0.9          
Bank Of Montreal [Member]            
Debt Instrument [Line Items]            
Line of credit $ 0 3,900        
Credit facility, borrowing capacity       $ 50,000 $ 35,000  
Proceeds from from short-term borrowings on credit facility 13,500 22,000        
Repayments of short-term borrowings on credit facility 17,400 18,100        
Line of credit, current borrowing capacity 49,000          
Letters of credit $ 1,000 $ 3,100        
Minimum [Member] | Senior Notes [Member]            
Debt Instrument [Line Items]            
Minimum fixed charge ratio 0.25          
Fixed charge coverage ratio for the quarter ending March 31, 2019 0.75          
Fixed charge coverage ratio for the quarter ending June 30, 2019 1.00          
Fixed charge coverage ratio for the quarter ending September 30, 2019 1.30          
Minimum [Member] | London Interbank Offered Rate (LIBOR) [Member]            
Debt Instrument [Line Items]            
Basis spread credit facility 1.50%          
Maximum [Member] | Senior Notes [Member]            
Debt Instrument [Line Items]            
Maximum leverage ratio 7.0          
Leverage ratio for the quarter ending March 31, 2019 5.5          
Leverage for the quarter ending June 30, 2019 4.5          
Leverage ratio for the quarter ending September 30, 2019 3.5          
Maximum [Member] | London Interbank Offered Rate (LIBOR) [Member]            
Debt Instrument [Line Items]            
Basis spread credit facility 2.00%          
Series A Senior Notes [Member] | Senior Notes [Member]            
Debt Instrument [Line Items]            
Senior notes $ 20,000          
Interest rate 3.73% 3.73%       7.73%
Series B Senior Notes [Member] | Senior Notes [Member]            
Debt Instrument [Line Items]            
Senior notes $ 15,000          
Interest rate 4.63% 4.63%       8.63%
Series C Senior Notes [Member] | Senior Notes [Member]            
Debt Instrument [Line Items]            
Senior notes $ 15,000          
Interest rate 4.78% 4.78%       8.78%