Earnings Per Share (Reconciliation Of Denominator For Basic And Diluted Earnings (Loss) Per Share) (Details) (USD $)	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share [Abstract]
Weighted average common shares - basic																	66,612,128	66,289,429	65,927,421
Plus incremental shares from: Assumed exercise of options																	277,497	352,066	372,737
Weighted average common shares - diluted																	66,889,625	66,641,495	66,300,158
Basic	$ 2.56	[1]	$ 2.55	[1]	$ 2.18	[1]	$ 1.84	[1]	$ 1.43	[1]	$ 1.30	[1]	$ 1.73	[1]	$ 1.32	[1]	$ 9.13	$ 5.78	$ 3.89
Diluted	$ 2.54	[1]	$ 2.54	[1]	$ 2.17	[1]	$ 1.84	[1]	$ 1.42	[1]	$ 1.30	[1]	$ 1.72	[1]	$ 1.31	[1]	$ 9.09	$ 5.75	$ 3.87

[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.