Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Net income (loss)	$ (488,100)	$ 167,454	$ (380,396)	$ 304,063
Number of common shares, Weighted average outstanding	348,162,723	347,132,830	348,081,399	346,984,194
Number of common shares, Weighted average and potential dilutive outstanding	348,162,723	349,970,819	348,081,399	349,840,044
Basic	$ (1.40)	$ 0.48	$ (1.09)	$ 0.88
Diluted	$ (1.40)	$ 0.48	$ (1.09)	$ 0.87
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,723,316	749,910	1,783,073	813,878
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	156,047	3,421	121,078	3,041