DEBT (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Aug. 01, 2019 USD ($)	Jun. 30, 2019 USD ($)	Oct. 31, 2017
Debt Instrument [Line Items]
Proceeds from from short-term borrowings on credit facility	$ 30,317	$ 13,500	$ 22,000
Repayments of short-term borrowings on credit facility	10,500	17,400	18,100
Line of credit, outstanding	19,817
Interest costs incurred	3,211	3,983	$ 11,822
Senior Notes [Member]
Debt Instrument [Line Items]
Senior notes	$ 50,000	50,000
Minimum fixed charge ratio	1.30
Maximum leverage ratio	3.5
Fixed charge coverage ratio	10.4
Leverage ratio	1.3
Bank Of Montreal [Member]
Debt Instrument [Line Items]
Credit facility, borrowing capacity				$ 75,000	$ 50,000
Credit facility, accordion feature				75,000
Credit facility, sublimit letters of credit				$ 7,500
Line of credit, outstanding		0
Letters of credit	$ 1,000	$ 1,000
Line of credit, current borrowing capacity	$ 54,200
Minimum [Member] | London Interbank Offered Rate (LIBOR) [Member] | Bank Of Montreal [Member]
Debt Instrument [Line Items]
Basis spread credit facility	1.25%
Maximum [Member] | London Interbank Offered Rate (LIBOR) [Member] | Bank Of Montreal [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%