CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets
Allowance for doubtful accounts receivable	$ 22,015	$ 18,050
Stockholders' Equity
Preferred stock, par value per share	$ 100	$ 100
Preferred stock, shares authorized	100,000	100,000
Preferred stock, shares issued	0	0
Common stock, par value per share	$ 1.00	$ 1.00
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	256,537,535	256,112,943
Treasury Stock, shares	101,109,186	101,109,186