Consolidated Condensed Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Accounts receivable, allowance	$ 1,024	$ 973
Common Stock, par value
Common Stock, shares authorized	55,000,000	55,000,000
Common Stock, shares issued	36,794,573	36,761,362
Common Stock, shares outstanding	36,794,573	36,761,362