Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2011	Dec. 31, 2010
Consolidated Balance Sheets [Abstract]
Preferred shares, par value	$ 0.01	$ 0.01
Preferred shares, shares authorized	5,000,000	5,000,000
Common shares, par value	$ 1	$ 1
Common shares, shares authorized	200,000,000	200,000,000
Common shares, shares issued	72,426,139	72,426,139
Common shares, shares outstanding	57,614,254	58,160,687
Treasury stock, shares	14,811,885	14,265,452