Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Statement Of Financial Position [Abstract]
Trade accounts receivable, allowance for doubtful accounts	$ 12,593	$ 11,969
Common shares, par value	$ 0.10	$ 0.10
Common shares, authorized	50,000,000	50,000,000
Common shares, issued	18,365,910	18,365,910
Common shares, outstanding	18,102,335	18,102,335