Net Rentable Space Sold.

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Number of properties sold.

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The current period expense charged against earnings on long-lived, physical assets not used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production.

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-Publisher FASB

-Name Accounting Standards Codification

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- Definition

Amount of expense incurred and directly related to generating revenue from leased and rented property or equipment.

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- Definition

Amount of gain (loss), after tax expense or benefit and not previously recognized, resulting from the sale of a business component.

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After tax income (loss) from operations of a business component (exclusive of any gain (loss) on disposal, or provision therefore) during the reporting period, until its disposal.

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- Definition

Gain (loss) related to the termination of a contract between the parties. The termination may be due to many causes including early termination of a lease by a lessee, a breach of contract by one party, or a failure to perform.

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Amount of income (loss) from a disposal group, net of income tax before extraordinary items allocable to noncontrolling interests. Includes, net of tax, income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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Amount of interest income earned from interest bearing assets not separately disclosed.

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No definition available.

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Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Includes selling, general and administrative expense.

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No definition available.

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- Definition

The total amount of lease revenue recognized for the period for which the lessee was obligated under leasing arrangements regardless of any other events or conditions. This amount excludes contingent revenue and sublease revenue.

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- Definition

Other real estate revenue not otherwise specified in the taxonomy.

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The aggregate revenue from real estate operations during the reporting period.

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A tax based on the assessed value of real estate by the local government. The tax is usually based on the value of property (including the land).

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In accordance with the provisions of their lease agreement, this element represents allowable charges due a landlord from its tenant. In retail store and office building leases, for example, tenant reimbursements may cover items such as taxes, utilities, and common area expenses.

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Discontinued Operations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended			0 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Apr. 07, 2014	Feb. 25, 2013 sqft
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from discontinued operations									$ 918	$ 4,207	$ 43,838
Revenue:
Rents									483,682	461,387	437,560
Tenant Reimbursements									84,879us-gaap_TenantReimbursements	79,087us-gaap_TenantReimbursements	77,060us-gaap_TenantReimbursements
Termination fees									8,000us-gaap_GainLossOnContractTermination	4,497us-gaap_GainLossOnContractTermination	3,233us-gaap_GainLossOnContractTermination
Other									3,221us-gaap_OtherRealEstateRevenue	4,186us-gaap_OtherRealEstateRevenue	5,710us-gaap_OtherRealEstateRevenue
Total revenue	147,810us-gaap_RealEstateRevenueNet	146,558us-gaap_RealEstateRevenueNet	150,500us-gaap_RealEstateRevenueNet	152,114us-gaap_RealEstateRevenueNet	138,658us-gaap_RealEstateRevenueNet	143,354us-gaap_RealEstateRevenueNet	140,664us-gaap_RealEstateRevenueNet	139,554us-gaap_RealEstateRevenueNet	596,982us-gaap_RealEstateRevenueNet	562,210us-gaap_RealEstateRevenueNet	535,679us-gaap_RealEstateRevenueNet
Expenses:
Property operating expenses									177,330	160,406	152,319
Real estate taxes									51,844us-gaap_RealEstateTaxExpense	55,612us-gaap_RealEstateTaxExpense	53,402us-gaap_RealEstateTaxExpense
Depreciation and amortization									208,569us-gaap_DepreciationAndAmortization	197,021us-gaap_DepreciationAndAmortization	188,382us-gaap_DepreciationAndAmortization
Total operating expenses									471,313us-gaap_OperatingExpenses	446,418us-gaap_OperatingExpenses	424,643us-gaap_OperatingExpenses
Interest Income									3,974us-gaap_InterestIncomeOther	1,044us-gaap_InterestIncomeOther	3,008us-gaap_InterestIncomeOther
Income from discontinued operations before gain on sale of interests in real estate									18	825	9,064
Net gain (loss) on disposition of discontinued operations									900	3,382	34,774
Princeton Pike Corporate Center [Member]
Expenses:
Net gain (loss) on disposition of discontinued operations										5,300		900
Net Rentable Space Sold													800,546
Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from discontinued operations									918	4,207	43,838
Revenue:
Rents									0	4,754	28,678
Tenant Reimbursements									26	355	2,353
Termination fees									0	0	11
Other									0	123	378
Total revenue									26	5,232	31,420
Expenses:
Property operating expenses									8	1,839	8,687
Real estate taxes									0	649	3,468
Depreciation and amortization									0	1,921	10,208
Total operating expenses									8	4,409	22,363
Interest Income									0	2	7
Income from discontinued operations before gain on sale of interests in real estate									18	825	9,064
Net gain (loss) on disposition of discontinued operations									$ 900	$ 3,382	$ 34,774
Net Rentable Space Sold	2,000,000								2,000,000
Number of properties sold (in properties)									28