Summary Of Significant Accounting Policies (Schedule Of Stock-Based Compensation Expense) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	$ 4,770	$ 5,119
Less: amounts capitalized	(754)	(1,269)
Total Stock-Based Compensation Expense	4,016	3,850
Income Tax Benefit	1,474	1,413
Stock Options And SARs [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	1,666	2,000
Restricted Stock Awards And Units [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	$ 3,104	$ 3,119