Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income (loss)	$ (54,053)		$ 175,173		$ (351,481)		$ 479,236
Number of common shares, Weighted average outstanding	348,649,630		347,239,793		348,272,192		347,070,330
Number of common shares, Issued upon assumed exercise of outstanding stock options			2,490,783				2,591,687
Number of common shares, Effect of issuance of nonvested restricted common stock			268,213				229,868
Number of common shares, Weighted average and potential dilutive outstanding	348,649,630	[1]	349,998,789	[1]	348,272,192	[1]	349,891,885	[1]
Basic	$ (0.16)		$ 0.50		$ (1.01)		$ 1.38
Diluted	$ (0.16)		$ 0.50		$ (1.01)		$ 1.37
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,664,232		783,823		1,685,398		811,552
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	560,848		5,645		580,227		7,114

[1] As we recognized a net loss for the three- and nine-months ended September 30, 2012, the unvested share-based payments and stock options were not recognized in diluted earnings per share (“Diluted EPS”) calculations as they would be antidilutive. Options for 1,664,232 shares and 560,848 shares of restricted stock were excluded from the calculation for the three months ended September 30, 2012 because they would have had an antidilutive effect. Options for 783,823 shares and 5,645 shares of restricted stock were excluded from the calculation for the three months ended September 30, 2011 because they would have had an antidilutive effect. Options for 1,685,398 shares and 580,227 shares of restricted stock were excluded from the calculation for the nine months ended September 30, 2012 because they would have had an antidilutive effect. Options for 811,552 shares and 7,114 shares of restricted stock were excluded from the calculation for the nine months ended September 30, 2011 because they would have had an antidilutive effect.