Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Condensed Consolidated Balance Sheets [Abstract]
Trade accounts receivable, allowance	$ 1,256	$ 926
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, shares authorized	70,000,000	70,000,000
Common stock, shares issued	37,854,000	37,712,000
Common stock, shares outstanding	37,854,000	37,712,000