Annual report pursuant to Section 13 and 15(d)

Earnings Per Share (Schedule Of Earnings Per Share Reconciliation) (Details)

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Earnings Per Share (Schedule Of Earnings Per Share Reconciliation) (Details) (USD $)
3 Months Ended 12 Months Ended
Dec. 31, 2011
Sep. 30, 2011
Jun. 30, 2011
Mar. 31, 2011
Dec. 31, 2010
Sep. 30, 2010
Jun. 30, 2010
Mar. 31, 2010
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]                      
Basic, Net income                 $ 108,422,000 $ 47,363,000 $ 23,627,000
Effect of dilutive securities, Stock options and awards                        
Diluted, Net income                 $ 108,422,000 $ 47,363,000 $ 23,627,000
Basic, Shares                 48,754,840 43,863,190 42,667,581
Effect of dilutive securities, Stock options and awards Shares                 452,123 392,902 350,067
Diluted, Shares                 49,206,963 44,256,092 43,017,648
Basic, Net income Per Share $ 0.59 $ 0.58 $ 0.57 $ 0.47 $ 0.32 $ 0.28 $ 0.24 $ 0.23 $ 2.22 $ 1.08 $ 0.55
Diluted, Net income Per Share $ 0.59 $ 0.57 $ 0.57 $ 0.47 $ 0.32 $ 0.28 $ 0.24 $ 0.23 $ 2.20 $ 1.07 $ 0.55
Stock Options At $9.07 Per Share [Member]
                     
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]                      
Shares excluded from the calculation of dilutive earnings                     64,889
Shares excluded from the calculation of dilutive earnings, price per share                     $ 9.07
Stock Options At $11.20 Per Share [Member]
                     
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]                      
Shares excluded from the calculation of dilutive earnings                     200,000
Shares excluded from the calculation of dilutive earnings, price per share                     $ 11.20