CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets
Allowance for doubtful accounts receivable	$ 18,050	$ 18,894
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	256,112,943	255,892,502