Stock-Based Compensation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount	$ (557)	$ (482)	$ (948)	$ (960)
Stock-based compensation, net of capitalization	3,135	2,456	6,159	4,903
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	3,622	2,863	6,978	5,726
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures			248,000
Weighted average grant date fair value (in dollars per share)			$ 52.80
Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 70	$ 75	$ 129	$ 137