Summary of Significant Accounting Policies (Details 4) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Y
Summary of estimated future compensation cost related to share-based awards granted to employees under long-term incentive plans
Unrecognized Compensation Expense	$ 16,987
Expected Weighted-average Recognition (Years)	2.3
SOSARs [Member]
Summary of estimated future compensation cost related to share-based awards granted to employees under long-term incentive plans
Unrecognized Compensation Expense	5,857
Expected Weighted-average Recognition (Years)	1.6
Performance Shares [Member]
Summary of estimated future compensation cost related to share-based awards granted to employees under long-term incentive plans
Unrecognized Compensation Expense	$ 11,130
Expected Weighted-average Recognition (Years)	2.6