Earnings Per Share (Schedule Of Earnings Per Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]
Income of basic earnings per common share	$ 67,522	$ 34,232	$ 178,827	$ 133,445
Income of effect of dilutive stock options, restricted stock, and stock appreciation rights (SARs)	0	0	0	0
Income of diluted earnings per common share	$ 67,522	$ 34,232	$ 178,827	$ 133,445
Weighted shares of basic earnings per common share	48,650	48,254	48,596	48,193
Weighted shares of effect of dilutive stock options, restricted stock, and stock appreciation rights (SARs)	527	404	458	317
Weighted shares of diluted earnings per common share	49,177	48,658	49,054	48,510
Per-Share amount of basic earnings per common share	$ 1.39	$ 0.71	$ 3.68	$ 2.77
Per-Share amount of effect of dilutive stock options, restricted stock, and stock appreciation rights (SARs)	$ (0.02)	$ (0.01)	$ (0.03)	$ (0.02)
Per-Share amount of diluted earnings per common share	$ 1.37	$ 0.70	$ 3.65	$ 2.75