Earnings Per Share (Details) (USD $) In Thousands, except Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Basic EPS
Net income	$ 38,611	$ (50,744)	$ 51,075	$ (63,601)
Net Income available to common stockholders, Shares	89,310,000	88,501,000	89,299,000	85,145,000
Net Income available to common stockholders, Per-Share	$ 0.43	$ (0.57)	$ 0.57	$ (0.75)
Effect of Dilutive Securities
Equity awards, Shares	402,000		384,000
Diluted EPS
Net income	$ 38,611	$ (50,744)	$ 51,075	$ (63,601)
Weighted Average Number of Shares Outstanding, Diluted, Total	89,712,000	88,501,000	89,683,000	85,145,000
Net Income (loss) available to common stockholders, Per-Share	$ 0.43	$ (0.57)	$ 0.57	$ (0.75)
Common Stock [Member]
Earnings Per Share (Textual) [Abstract]
Number of shares of common stock equivalents related to convertible debt	1,056,901	5,935,972	1,419,282	5,935,972
Stock Options [Member]
Earnings Per Share (Textual) [Abstract]
Number of shares of common stock equivalents related to convertible debt		510,242		510,242