Earnings Per Share (Schedule Of Earnings Per Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Earnings Per Share [Abstract]
Income of basic earnings per common share	$ 59,007	$ (19,302)	$ 99,213	$ 33,137
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	$ 59,007	$ (19,302)	$ 99,213	$ 33,137
Weighted shares of basic earnings per common share	48,208	47,906	48,162	47,868
Weighted shares of effect of dilutive stock options, restricted stock and stock appreciation rights (SARs)	298	0	329	245
Weighted shares of diluted earnings per common share	48,506	47,906	48,491	48,113
Per-Share amount of basic earnings per common share	$ 1.22	$ (0.40)	$ 2.06	$ 0.69
Per-Share amount of effect of dilutive stock options, restricted stock and stock appreciation rights (SARs)	$ 0.00	$ 0.00	$ (0.01)	$ 0.00
Per-Share amount of diluted earnings per common share	$ 1.22	$ (0.40)	$ 2.05	$ 0.69