Annual report pursuant to Section 13 and 15(d)

Selected Quarterly Financial Data (Schedule Of Quarterly Financial Data) (Details)

v2.4.0.6
Selected Quarterly Financial Data (Schedule Of Quarterly Financial Data) (Details) (USD $)
In Thousands, except Per Share data, unless otherwise specified
 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
Selected Quarterly Financial Data [Abstract]                      
Revenues $ 261,899 $ 245,371 $ 252,922 $ 210,855 $ 186,956 $ 169,575 $ 179,667 $ 169,585 $ 971,047 $ 705,783 $ 610,996
Operating income 80,936 95,333 115,643 37,548 34,053 36,847 40,178 55,711 329,460 166,789 (219,859)
Net income $ 46,065 $ 52,928 $ 55,175 $ 18,649 $ 20,519 $ 27,188 $ 27,870 $ 42,315 $ 172,817 $ 117,892 $ (187,919)
Basic and diluted earnings per common share $ 0.61 [1] $ 0.70 [1] $ 0.73 [1] $ 0.25 [1] $ 0.27 [1] $ 0.36 [1] $ 0.37 [1] $ 0.57 [1] $ 2.29 $ 1.58 $ (2.51)
[1] The sum of the individual quarterly earnings per share may not agree with year-to-date earnings per share because each quarterly calculation is based on the income for that quarter and the weighted average number of shares outstanding during that quarter.