Earnings Per Share (Earnings (Loss) Per Share) (Details) (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Earnings Per Share
Income/(loss) of basic earnings per common share	$ 53,360	$ 34,491	$ 144,206	$ 102,819
Income/(loss) of effect of dilutive stock options, restricted stock and stock appreciation rights (SARs)	0	0	0	0
Income/(loss) of diluted earnings per common share	$ 53,360	$ 34,491	$ 144,206	$ 102,819
Weighted shares of basic earnings per common share	47,687	47,358	47,642	47,217
Weighted shares of effect of dilutive stock options, restricted stock and stock appreciation rights (SARs)	281	137	290	167
Weighted shares of diluted earnings per common share	47,968	47,495	47,932	47,384
Per-share amount of basic earnings per common share	$ 1.12	$ 0.73	$ 3.03	$ 2.18
Per-share amount of effect of dilutive stock options, restricted stock and stock appreciation rights (SARs)	$ (0.01)	$ 0.00	$ (0.02)	$ (0.01)
Per-share amount of diluted earnings per common share	$ 1.11	$ 0.73	$ 3.01	$ 2.17