CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
CONDENSED CONSOLIDATED BALANCE SHEETS
Trade accounts receivable, allowance for doubtful accounts (in dollars)	$ 1,991	$ 1,297
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	175,772,173	175,772,173
Common stock, shares issued	158,210,719	158,210,719
Common stock held in treasury, at cost	2,106,865	2,448,553