Earnings Per Share (Reconciliation Of Denominator For Basic And Diluted Earnings (Loss) Per Share) (Details) (USD $)	3 Months Ended																12 Months Ended
	Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2010		Sep. 30, 2010		Jun. 30, 2010		Mar. 31, 2010		Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Earnings Per Share [Abstract]
Weighted average common shares - basic																	65,927,421	65,472,875	65,323,101
Plus incremental shares from: Assumed exercise of options																	372,737	203,789	98,289
Weighted average common shares - diluted																	66,300,158	65,676,664	65,421,390
Earnings per share: Basic	$ 0.40	[1]	$ 1.02	[1]	$ 1.22	[1]	$ 1.26	[1]	$ 1.27		$ 0.95		$ 0.86		$ 0.27		$ 3.89	$ 3.35	$ 0.80
Earnings per share: Diluted	$ 0.40	[1]	$ 1.01	[1]	$ 1.21	[1]	$ 1.25	[1]	$ 1.26	[1]	$ 0.95	[1]	$ 0.86	[1]	$ 0.27	[1]	$ 3.87	$ 3.34	$ 0.80

[1] Basic and diluted earnings per common share ("EPS") for each quarter is computed using the weighted average shares outstanding during that quarter, while EPS for the year is computed using the weighted average shares outstanding for the year. As a result, the sum of the EPS for each of the four quarters may not equal the EPS for the year.