Incentive Plan (Stock Options) (Narrative) (Details) (Potentially Dilutive Outstanding Stock Options [Member], USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option expense	$ 0	$ 200,000	$ 200,000	$ 700,000
Capitalized expense related to construction and leasing activities	0	100,000	100,000	200,000
Unearned compensation	$ 0		$ 0		$ 300,000
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			4 years
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			5 years