Deferred Leasing Costs and Acquisition-related Intangibles Assets and Liabilities, net (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Deferred Leasing Costs and Acquisition-related Intangible Assets
Total acquisitions-related intangible liabilities, net	$ 29,885	$ 16,844
Total deferred leasing costs and acquisition-related intangible assets, net	153,231	131,066
Deferred Leasing Costs [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets
Total acquisiition-related intangible liabilities, net	131,098	128,980
Accumulated amortization	(43,921)	(45,869)
Finite-lived intangible assets, net	87,177	83,111
Leases Acquired in Place Above Market Adjustment [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets
Total acquisiition-related intangible liabilities, net	27,922	21,321
Accumulated amortization	(4,747)	(2,163)
Finite-lived intangible assets, net	23,175	19,158
Leases Acquired In Place [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets
Total acquisiition-related intangible liabilities, net	50,915	36,964
Accumulated amortization	(8,036)	(8,167)
Finite-lived intangible assets, net	42,879	28,797
Leases Acquired In Place Above Market Ground Leases Adjustment [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets
Total acquisiition-related intangible liabilities, net	5,200	0
Accumulated amortization	(5)	0
Finite-lived intangible assets, net	5,195	0
Leases Acquired In Place Below Market Adjustment [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets
Total acquisiition-related intangible liabilities, net	27,152	21,938
Accumulated amortization	(2,462)	(5,094)
Finite-lived intangible assets, net	$ 24,690	$ 16,844

The identifiable intangible liability established upon acquisition based on an unfavorable difference between the terms of an acquired lease and the current market terms for that lease at the acquisition date and the ground lease obligation established upon acquisition based on an unfavorable difference between the terms of the acquired ground lease and the current market terms for that lease at the acquisition date.

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- Definition

Deferred Leasing Costs and Acquisition-related Intangible Assets.

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- Definition

This element represents (1) 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; (2) the identifiable intangible asset established upon acquisition based on a favorable difference between the terms of an acquired lease and the current market terms for that lease at the acquisition date; and (3) the amount of value allocated by a lessor (acquirer) to lease agreements which exist at acquisition of a leased property. This element is net of accumulated amortization.

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- Definition

The accumulated amount of amortization of a major finite-lived intangible asset class. A major class is composed of intangible assets that can be grouped together because they are similar, either by their nature or by their use in the operations of a company.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 45
-Subparagraph a(1)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6905858&loc=d3e16323-109275

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- Definition

Sum of the gross carrying amounts before accumulated amortization as of the balance sheet date of all intangible assets having statutory or estimated useful lives. The aggregate gross carrying amount (including any previously recognized impairment charges) of a major finite-lived intangible asset class. A major class is composed of intangible assets that can be grouped together because they are similar, either by their nature or by their use in the operations of a company.

+ References

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The aggregate sum of gross carrying value of a major finite-lived intangible asset class, less accumulated amortization and any impairment charges. A major class is composed of intangible assets that can be grouped together because they are similar, either by their nature or by their use in the operations of a company.

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