Net Income (Loss) Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Numerator:
Income (loss) from continuing operations	$ (1,065,555)	$ 363,598	$ 389,425
Income (loss) from discontinued operations	$ 5,180		$ (3,628)
Denominator:
Average number of common shares outstanding	62,536,000	60,257,000	53,179,000
Effect of dilutive securities:
Stock awards and warrants (in shares)		354,000	521,000
Weighted average shares, diluted	62,536,000	60,611,000	53,700,000
Income (loss) from continuing operations (in dollars per share)	$ (17.04)	$ 6.03	$ 7.32
Income (loss) from discontinued operations (in dollars per share)	$ 0.08		$ (0.07)
Net income (loss) (in dollars per share)	$ (16.96)	$ 6.03	$ 7.25
Income (loss) from continuing operations, diluted (in dollars per share)	$ (17.04)	$ 6.00	$ 7.25
Income (loss) from discontinued operations, diluted (in dollars per share)	$ 0.08		$ (0.07)
Net income (loss) (in dollars per share)	$ (16.96)	$ 6.00	$ 7.18
Anti-dilutive securities excluded from earnings per share calculation	238,210	31,511	25,177