CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
CONDENSED CONSOLIDATED BALANCE SHEETS
Trade accounts receivable, allowance for doubtful accounts (in dollars)	$ 1,130	$ 1,136
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	158,160,719
Common stock, shares held in treasury, at cost	1,327,093