Consolidated Condensed Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Allowance for doubtful trade accounts receivable	$ 9,539	$ 9,169
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	65,057,763	65,790,112
Treasury stock, shares	15,475,773	14,743,424