INVENTORIES (Inventories) (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015
INVENTORIES [Abstract]
Finished products	[1]	$ 293,619	$ 297,925
Raw materials		22,648	21,765
Products in process		1,480	1,008
Operating supplies and other		27,869	26,375
Total		345,616	347,073
Encumbered inventories		$ 2,841	$ 4,452

[1] Includes inventories encumbered by volumetric production payments (see Note 1, caption Deferred Revenue), as follows: December 31, 2016 - $2,841 thousand and December 31, 2015 - $4,452 thousand.