Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Statement Of Financial Position [Abstract]
Trade accounts receivable, allowances	$ 13,543	$ 9,341
Common shares, par value	$ 0.10	$ 0.10
Common shares, authorized	50,000,000	50,000,000
Common shares, issued	19,339,329	18,465,444
Common shares, outstanding	19,339,329	18,465,444