Consolidated Condensed Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data	Jun. 30, 2011	Dec. 31, 2010
Consolidated Condensed Balance Sheets
Allowance for doubtful accounts receivable	$ 10,156	$ 9,484
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	80,533,536	80,533,536
Common stock, shares outstanding	72,805,115	72,644,998
Treasury stock, shares	7,728,421	7,888,538