Stock-Based Compensation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Capitalized stock-based compensation	$ (696)	[1]	$ (391)	[1]
Stock-based compensation, net of capitalization	2,272		3,024
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	2,916		3,356
Shares granted	238,941
Weighted average grant date fair value (in dollars per share)	$ 47.79
Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 52	[2]	$ 59	[2]

[1] Includes compensation expense specifically identifiable to development and leasing activities.

[2] Includes amortization of the grant date fair value of restricted stock awards over the respective vesting periods.