Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Condensed Consolidated Balance Sheets [Abstract]
Allowance for doubtful accounts, accounts receivable	$ 1,424	$ 1,094
Property, plant and equipment, accumulated depreciation	$ 323,881	$ 312,983
Preferred shares, par value	$ 0.10	$ 0.10
Preferred shares, shares authorized	5,000,000	5,000,000
Preferred shares, issued	0	0
Common shares, par value	$ 0.10	$ 0.10
Common shares, shares authorized	145,000,000	145,000,000
Common shares, issued	56,219,000	57,902,000
Common shares, outstanding	56,108,000	57,791,000
Treasury shares, shares	111,000	111,000