INVENTORIES (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
INVENTORIES [Abstract]
Inventory classified as long-term assets (other noncurrent assets)	$ 9,980	$ 11,810
Inventories valued under the LIFO method	308,257	252,808
Decrease in cost of revenues due to the effect of the LIFO liquidation	132	2,714	$ 3,956
Increase in net earnings due to the effect of the LIFO liquidation	99	1,662	2,419
Excess of estimated current cost over LIFO cost	175,844	168,829
Approximate effect on net earnings due to the adoption of the LIFO method	$ 5,223	$ 8,092	$ (8,338)