Deferred Costs (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Components of Deferred Costs Net [Abstract]
Leasing Costs, Total Cost	$ 164,081	$ 155,885
Financing Costs, Total Cost	40,401	40,317
Total Cost	204,482	196,202
Leasing Costs, Accumulated Amortization	(64,065)	(58,805)
Financing Costs, Accumulated Amortization	(15,193)	(14,443)
Total, Accumulated Amortization	(79,258)	(73,248)
Leasing Costs, Deferred Costs, net	100,016	97,080
Financing Costs, Deferred Costs, net	25,208	25,874
Deferred Costs	$ 125,224	$ 122,954