Consolidated Statements of Financial Position (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Statement of Financial Position [Abstract]
Allowances for accounts receivable	$ 3,255	$ 3,863
Preferred Shares, shares authorized (in shares)	1,000,000	1,000,000
Preferred Shares, shares issued (in shares)	0	0
Preferred Shares, shares outstanding (in shares)	0	0
Common Shares, shares authorized (in shares)	60,000,000	60,000,000
Common Shares, shares outstanding (in shares)	33,480,189	33,420,488
Common shares, treasury (in shares)	4,356,160	4,492,169