Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2013

Real Estate Fund [Abstract]

Real Estate Fund Accounting [Policy Text Block]

The Fund is accounted for under the AICPA Investment Company Guide and its investments are reported on its balance sheet at fair value, with changes in value each period recognized in earnings. We consolidate the accounts of the Fund into our consolidated financial statements, retaining the fair value basis of accounting.

Derivative Instruments and Marketable Securities [Abstract]

Marketable Securities, Available-for-sale Securities, Policy [Policy Text Block]

Our portfolio of marketable securities is comprised of equity securities that are classified as available for sale. Available for sale securities are presented on our consolidated balance sheets at fair value. Unrealized gains and losses resulting from the mark-to-market of these securities are included in “other comprehensive income (loss).” Realized gains and losses are recognized in earnings only upon the sale of the securities and are recorded based on the weighted average cost of such securities.

Derivatives, Methods of Accounting, Derivatives Not Designated or Qualifying as Hedges [Policy Text Block]

Gains and losses from the mark-to-market of the underlying common shares are recognized in “interest and other investmentincome (loss), net” on our consolidated statements of income.

Redeemable Partnership Units Disclosure [Abstract]

Redeemable Noncontrolling Interests [Policy Text Block]

Redeemable partnership units on our consolidated balance sheets are primarily comprised of Class A unitsheld by third parties. Redeemable partnership units on our consolidated balance sheets are recorded at the greater of their carrying amount or redemption value at the end of each reporting period. Changes in the value from period to period are charged to “partners' capital” on our consolidated balance sheets.

Fair Value Disclosures [Abstract]

Fair Value Measurement Policy [Policy Text Block]

In determining fair value, we utilize valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible, as well as consider counterparty credit risk in our assessment of fair value. Considerable judgment is necessary to interpret Level 2 and 3 inputs in determining the fair value of our financial and non-financial assets and liabilities. Accordingly, our fair value estimates, which are made at the end of each reporting period, may be different than the amounts that may ultimately be realized upon sale or disposition of these assets.

Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis

Financial assets and liabilities that are measured at fair value in our consolidated financial statements consist of(i) marketable securities, (ii) Real Estate Fund investments,(iii) the assets in our deferred compensation plan (for which there is a corresponding liability on our consolidated balance sheet), (iv) derivative positions in marketable equity securities,(v) interest rate swaps and (vi) mandatorily redeemable instruments (Series G-1 through G-4 convertible preferred units and Series D-13 cumulative redeemable preferred units).

Fair Value Measurements on a Nonrecurring Basis

Assets measured at fair value on a nonrecurring basis on our consolidated balance sheets consist primarily of our investment in Toys “R” Us and real estate assets that were written-down to estimated fair value at December 31, 2012. The fair values of these assets were determined using widely accepted valuation techniques, including (i) discounted cash flow analysis, which considers, among other things, leasing assumptions, growth rates, discount rates and terminal capitalization rates, (ii) income capitalization approach, which considers prevailing market capitalization rates, and (iii) comparable sales activity. Generally, we consider multiple valuation techniques when measuring fair values but in certain circumstances, a single valuation technique may be appropriate.

Financial Assets and Liabilities not Measured at Fair Value

Financial assets and liabilities that are not measured at fair value on our consolidated balance sheets include cash equivalents (primarily money market funds, which invest in obligations of the United States government), mortgage and mezzanine loans receivable and our secured and unsecured debt. Estimates of the fair value of these instruments are determined by the standard practice of modeling the contractual cash flows required under the instrument and discounting them back to their present value at the appropriate current risk adjusted interest rate, which isprovided by a third-party specialist. For floating rate debt, we use forward rates derived from observable market yield curves to project the expected cash flows we would be required to make under the instrument. The fair value of cash equivalents is classified as Level 1 and the fair value of our mortgage and mezzanine loans receivableis classified as Level 3. The fair value of our secured and unsecured debt are classified as Level 2.