Net Income Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Numerator for Basic and Diluted Earnings per Share - [Abstract]
Net Income	$ 1,091,123	$ 160,654	$ 546,627
Denominator for Basic Earnings per Share - [Abstract]
Weighted Average Shares	262,735,000	250,876,000	248,996,000
Potential Dilutive Common Shares -[Abstract]
Stock Options/SARs	1,707,000	1,991,000	1,691,000
Restricted Stock and Restricted Stock Units	1,826,000	1,633,000	1,197,000
Denominator for Diluted Earnings per Share - [Abstract]
Adjusted Diluted Weighted Average Shares	266,268,000	254,500,000	251,884,000
Net Income Per Share Available to Common Stockholders [Abstract]
Basic	$ 4.15	$ 0.64	$ 2.20
Diluted	$ 4.10	$ 0.63	$ 2.17
Antidilutive Stock Options and SARs excluded from Diluted Earnings Per Share Calculation	400,000	300,000	2,500,000