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PROPERTY, PLANT AND EQUIPMENT (Details 7) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Property, plant and equipment [abstract]      
Average rate of capitalization of capitalized interest costs 4.21% 3.54% 2.79%
Costs of capitalized interest $ 11,053 $ (696) $ 22,551