Consolidated Statements of Financial Position (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Consolidated Statements of Financial Position [Abstract]
Allowances for accounts receivable	$ 3,863	$ 2,950
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	33,420,488	35,315,732
Treasury Shares, shares	4,492,169	2,592,175