Earnings Per Share (Computation of Basic and Diluted Earnings Per Share ) (Details) (USD $) In Thousands, except Per Share data	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Earnings Per Share
Net income/(loss)	$ 22,304		$ (84,336)		$ 57,118		$ (39,487)
Average shares used in basic computation	52,367		51,201		52,610		47,865
Dilutive effect of stock options and units	10,785	[1]	10,633	[1]	10,564	[1]	7,728	[1]
Weighted Average Number Diluted Shares Outstanding Adjustment, Total	63,152		61,834		63,174		55,593
Basic	$ 0.43		$ (1.65)		$ 1.09		$ (0.82)
Diluted	$ 0.35	[1]	$ (1.65)	[1]	$ 0.90	[1]	$ (0.82)	[1]

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