Summary Of Significant Accounting Policies (Schedule Of Unamortized Stock-Based Compensation Expense And Weighted Average Remaining Amortization Period) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 years
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unamortized Stock-Based Compensation Expense	$ 8,955
Weighted Average Remaining Amortization Period (in years)	2.71
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unamortized Stock-Based Compensation Expense	11,525
Weighted Average Remaining Amortization Period (in years)	2.61
Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unamortized Stock-Based Compensation Expense	$ 2,099
Weighted Average Remaining Amortization Period (in years)	1.59