Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 4,883	$ 4,799
Common shares, par value (dollars per share)	$ 0	$ 0
Common shares, shares authorized (shares)	42,000,000	42,000,000
Common shares, shares issued (shares)	19,198,000	19,198,000
Preferred shares, par value (dollars per share)	$ 0	$ 0
Preferred shares, shares authorized (shares)	1,000,000	1,000,000
Preferred shares, shares issued (shares)	0	0
Treasury shares, at cost (shares)	554,000	697,000