Basis of Presentation, Significant Accounting Policies, and Recently Issued Accounting Standards Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted Average Number Diluted Shares Outstanding Adjustment	3,809	1,720	0
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	0	1,152
Net Income (loss)	$ 215,416	$ 196,837	$ (99,370)
Weighted Average Number of Shares Outstanding, Basic	63,755	62,969	62,457
Incremental Common Shares Attributable to Share-based Payment Arrangements	2,592	1,720	0
Incremental Common Shares Attributable to Conversion of Debt Securities	1,217	0	0
Weighted Average Number of Shares Outstanding, Diluted	67,564	64,689	62,457
Basic net income (loss) per common share	$ 3.38	$ 3.13	$ (1.59)
Diluted net income (loss) per common share	$ 3.19	$ 3.04	$ (1.59)