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, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Earnings Per Share [Abstract]
Income of Basic earnings (loss) per common share	$ (19,302)	$ 49,819	$ 33,137	$ 90,846
Income of Effect of dilutive stock options, restricted stock and stock appreciation rights (SARs)	0	0	0	0
Income of Diluted earnings (loss) per common share	$ (19,302)	$ 49,819	$ 33,137	$ 90,846
Weighted Shares of Basic earnings per common share	47,906	47,655	47,868	47,620
Weighted Shares of Effect of dilutive stock options, restricted stock and stock appreciation rights (SARs)	0	328	245	324
Weighted Shares of Diluted earnings per common share	47,906	47,983	48,113	47,944
Per-Share Amount of Basic earnings per common share	$ (0.40)	$ 1.05	$ 0.69	$ 1.91
Per-Share Amount of Effect of dilutive stock options, restricted stock and stock appreciation rights (SARs)	$ 0.00	$ (0.01)	$ 0.00	$ (0.02)
Per-Share Amount of Diluted earnings per common share	$ (0.40)	$ 1.04	$ 0.69	$ 1.89