Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Consolidated Balance Sheets [Abstract]
Allowance for trade accounts receivable	$ 1,677	$ 1,230
Unamortized premium on notes	$ 1,790	$ 1,892
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	80,000,000	80,000,000
Common stock, shares issued	43,500,032	42,530,809
Common stock, shares outstanding	42,748,128	42,486,645
Treasury stock, shares	751,904	44,164