Earnings Per Share (Schedule Of Earnings Per Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share [Abstract]
Income of basic earnings per common share	$ 56,945	$ 40,206
Income of effect of dilutive stock options, restricted stock and stock appreciation rights (SARs)	0	0
Income of diluted earnings per common share	$ 56,945	$ 40,206
Weighted shares of basic earnings per common share	48,493	48,117
Weighted shares of effect of dilutive stock options, restricted stock and stock appreciation rights (SARs)	379	295
Weighted shares of diluted earnings per common share	48,872	48,412
Per-Share amount of basic earnings per common share	$ 1.17	$ 0.84
Per-Share amount of effect of dilutive stock options, restricted stock and stock appreciation rights (SARs)	$ 0.00	$ (0.01)
Per-Share amount of diluted earnings per common share	$ 1.17	$ 0.83