Fair Value Measurements	6 Months Ended
Fair Value Measurements	Jun. 30, 2011
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Trading Securities Held in Trust The Company has investments in marketable securities that are classified as trading securities held in trust on the accompanying Consolidated Balance Sheets. The fair value of the trading securities held in trust was determined using Level 1 quoted prices in active markets. The fair value of the trading securities held in trust was $23.3 million and $20.9 million at June 30, 2011 and December 31, 2010, respectively. Notes Payable The fair value of the Company's notes payable are estimated based on the current rates available to the Company for debt of the same terms and remaining maturities. Fixed rate loans assumed in connection with real estate acquisitions are recorded in the accompanying consolidated financial statements at fair value at the time the property is acquired including those loans assumed in distribution-in-kind liquidations. Each of these fair value measurements fall within Level 3 of the fair value hierarchy. Based on the estimates used by the Company, the fair value of notes payable was $2.2 billion at both June 30, 2011 and December 31, 2010.

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

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