Deferred Costs (Details Textuals) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Leased Assets [Line Items]
Deferred Costs, Leasing, Net	$ 100,016,000us-gaap_DeferredCostsLeasingNet	$ 97,080,000us-gaap_DeferredCostsLeasingNet
Deferred Costs (Textuals) [Abstract]
Capitalized internal direct leasing costs	$ 7,100,000	$ 7,500,000	$ 7,500,000

- Definition

This element represents costs incurred by the lessor that are (a) costs to originate a lease incurred in transactions with independent third parties that (i) result directly from and are essential to acquire that lease and (ii) would not have been incurred had that leasing transaction not occurred and (b) certain costs directly related to specified activities performed by the lessor for that lease. Those activities are: evaluating the prospective lessee's financial condition; evaluating and recording guarantees, collateral, and other security arrangements; negotiating lease terms; preparing and processing lease documents; and closing the transaction. This element is net of accumulated amortization.

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