CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
CONSOLIDATED BALANCE SHEETS [Abstract]
Customers, allowance for doubtful accounts	$ 2,649	$ 2,813
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	480,000,000	480,000,000
Common stock, shares outstanding	132,324,000	132,339,000