Summary Of Significant Accounting Policies (Schedule Of Stock-Based Compensation Expense) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	$ 2,501	$ 8,244	$ 7,272	$ 13,364
Less: Amounts Capitalized	(985)	(1,439)	(1,740)	(2,709)
Total Stock-Based Compensation Expense	1,516	6,805	5,532	10,655
Income Tax Benefit	562	2,500	2,052	3,915
Stock Options And SARs [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	(2,975)	4,914	(1,309)	6,914
Restricted Stock Awards And Units [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	$ 5,476	$ 3,330	$ 8,581	$ 6,450