Stock-Based Compensation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 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	$ (620)	$ (492)	$ (1,567)	$ (1,453)
Stock-based compensation, net of capitalization	3,067	2,429	9,227	7,331
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	3,622	2,863	10,600	8,589
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	$ 65	$ 58	$ 194	$ 195