CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Accounts receivable, allowance, in dollars	$ 4,425	$ 4,459
Common stock, par value, in dollars per share	$ 1.00	$ 1.00
Common stock, shares authorized	750,000,000	750,000,000
Common stock, shares issued	469,435,678	468,081,489
Common stock, shares outstanding	469,435,678	468,081,489