Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Trade accounts receivable, allowance for doubtful accounts	$ 4,073	$ 7,463
Common shares, par value	$ 0.10	$ 0.10
Common shares, authorized	50,000,000	50,000,000
Common shares, issued	18,875,184	18,579,688
Common shares, outstanding	18,875,184	18,579,688