Per Share Data (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Numerator
Net income (loss) - basic and diluted	$ 76,743	$ (62,505)	$ 88,394	$ (105,952)
Denominator
Weighted-average shares - basic (in shares)	94,589	90,436	94,017	89,799
Effect of dilutive securities (in shares):
Stock options (in shares)	14,055		13,964
Restricted stock (in shares)	692		676
Warrants (in shares)	831		341
Dilutive potential shares (in shares)	15,578		14,981
Weighted-average shares - diluted (in shares)	110,167	90,436	108,998	89,799
Net income (loss) per share - basic (in dollars per share)	$ 0.81	$ (0.69)	$ 0.94	$ (1.18)
Net income (loss) per share - diluted (in dollars per share)	$ 0.70	$ (0.69)	$ 0.81	$ (1.18)
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average number, in thousands (in shares)	89	20,967	47	21,668
Weighted average exercise price (in dollars per share)	$ 124.64	$ 20.71	$ 123.29	$ 20.48
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average number, in thousands (in shares)		846	11	846
Convertible Senior Notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average number, in thousands (in shares)	4,761		4,761
Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average number, in thousands (in shares)	3,930		4,420