Condensed Consolidated Statements of Financial Position (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Condensed Consolidated Statements of Financial Position [Abstract]
Allowances for accounts receivable	$ 3,238	$ 3,863
Preferred Shares, shares authorized	1,000,000	1,000,000
Preferred Shares, shares issued
Preferred Shares, shares outstanding
Common Shares, par value
Common Shares, shares authorized	60,000,000	60,000,000
Common Shares, shares outstanding	33,460,491	33,420,488
Treasury shares, shares	4,318,641	4,492,169