Summary Of Significant Accounting Policies (Schedule Of Stock-Based Compensation Expense) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	$ 7,789	$ 4,770
Less: amounts capitalized	(1,306)	(754)
Total Stock-Based Compensation Expense	6,483	4,016
Income Tax Benefit	(2,363)	(1,474)
Stock Options And SARs [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	3,932	1,666
Restricted Stock Awards And Units [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	$ 3,857	$ 3,104