Stock Compensation Plans (Details Textual) (USD $)	12 Months Ended					12 Months Ended			12 Months Ended				12 Months Ended			3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2008	May 06, 2005	Dec. 31, 2008 Stock Only Stock Appreciation Rights	Dec. 31, 2007 Stock Only Stock Appreciation Rights	Dec. 31, 2013 SOSARs and Stock Options	Dec. 31, 2013 Restricted Stock Awards	Dec. 31, 2013 Performance Share Units	Dec. 31, 2012 Performance Share Units	Dec. 31, 2011 Performance Share Units	Dec. 31, 2013 Performance Share Units Executive Officer	Dec. 31, 2013 Employee Stock	May 06, 2005 Prior Plan	Mar. 31, 2013 Grants Prior 2013 Restricted Stock Awards	Mar. 31, 2013 Grants in 2013 Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized to grant under LT Plan					600,000
Number of shares remained available	637,500													285,000	639,000
Number of additional shares available under LT Plan				750,000
Maximum term for options granted	10 years
Compensation expense recognized	$ 4,300,000	$ 4,000,000	$ 4,100,000
Term of granting options to directors and management personnel						5 years	5 years
General vesting period of options granted						3 years	3 years									3 years	2 years 3 months
Number of shares issued									60,168				103,272
Total unrecognized compensation cost								$ 0	$ 3,200,000	$ 2,600,000
Period for recognition of compensation cost									2 years	2 years
Percentage of maximum amount available for issuance										100.00%	40.00%	50.00%
Term of Treasury issues														1 year