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           Investments In Unconsolidated Joint Ventures (ELMAJO Urban Renewal Associates, L.L.C.) (Narrative) (Details) (USD $) 
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        3 Months Ended | 3 Months Ended | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 
           Mar. 31, 2013 
         | 
        
           Mar. 31, 2013
 
          Elmajo Urban Renewal Associates, L.L.C. [Member] 
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           Oct. 23, 2012
 
          Elmajo Urban Renewal Associates, L.L.C. [Member]
 
          property
 
          item 
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           Mar. 31, 2013
 
          Elmajo Urban Renewal Associates, L.L.C. [Member]
 
          ELMAJO Management, Inc. [Member] 
         | 
        
           Oct. 23, 2012
 
          Lincoln Harbor Project, Building A [Member]
 
          Elmajo Urban Renewal Associates, L.L.C. [Member]
 
          item 
         | 
        
           Oct. 23, 2012
 
          Lincoln Harbor Project, Building C [Member]
 
          Elmajo Urban Renewal Associates, L.L.C. [Member]
 
          item 
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           Jan. 31, 2013
 
          Lincoln Harbor Project, Building B [Member]
 
          item 
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           Mar. 31, 2013
 
          Lincoln Harbor Project [Member] 
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           Mar. 31, 2013
 
          Lincoln Harbor Project [Member]
 
          Elmajo Urban Renewal Associates, L.L.C. [Member] 
         | 
        
           Mar. 31, 2013
 
          Construction Loan [Member]
 
          Lincoln Harbor Project Buildings A And C [Member]
 
          ELMAJO Management, Inc. [Member] 
         | 
      |
| Schedule of Equity Method Investments [Line Items] | ||||||||||
| Residual ownership interest | 7.50% | |||||||||
| Number of properties | 3 | |||||||||
| Number of units | 582 | 181 | 174 | 227 | ||||||
| Total project costs | $ 220,000,000 | |||||||||
| Percentage return on unrecovered capital | 8.50% | |||||||||
| Capital balance | 66,000,000 | |||||||||
| Accumulated unpaid operating return | 10,200,000 | |||||||||
| Maximum borrowing capacity | 600,000,000 | 95,000,000 | ||||||||
| Amount outstanding | 14,400,000 | |||||||||
| Spread over LIBOR | 2.10% | |||||||||
| Loan maturity date | Jun. 01, 2016 | |||||||||
| Loan extension period | 1 year | |||||||||
| Extension fee | 0.25% | |||||||||
| Development management and other services fees | 240,000 | |||||||||
| Funding requirements | $ 0 | |||||||||
| Holding and distribution pattern under operating agreement | The operating agreements of ELMAJO Urban Renewal Associates, LLC ("ELMAJO UR"), the entity which owns the Lincoln Harbor Project, Building A and C, and Estuary UR, the entity that owns the Lincoln Harbor Project Building B, provides, among other things, for the distribution of net distributable cash to the members, as follows:First, to the members to the extent of and in proportion to their respective preferred return of 8.50 percent on the member's unrecovered capital; andSecond, to the members in accordance with their ownership percentages. | |||||||||
| X | ||||||||||
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- Definition 
          Accumulated Unpaid Operating Return No definition available. 
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| X | ||||||||||
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- Definition 
          Debt Instrument Extension Fee Percentage No definition available. 
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| X | ||||||||||
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- Definition 
          Debt Instrument Extension Period No definition available. 
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| X | ||||||||||
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- Definition 
          Development Management And Other Services Fees No definition available. 
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| X | ||||||||||
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- Definition 
          Estimated Cost Of Project No definition available. 
  | 
        
| X | ||||||||||
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- Definition 
          Holding And Distribution Pattern Under Operating Agreement No definition available. 
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| X | ||||||||||
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- Definition 
          Percentage Return On Unrecovered Capital No definition available. 
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| X | ||||||||||
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- Definition 
          Project Costs, Required Funding Amount No definition available. 
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| X | ||||||||||
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- Definition 
          Residual Ownership Interest No definition available. 
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| X | ||||||||||
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- Definition 
          The percentage points added to the reference rate to compute the variable rate on the debt instrument. No definition available. 
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| X | ||||||||||
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- Definition 
          Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition 
          Amount borrowed under the credit facility as of the balance sheet date. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition 
          Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition 
          The number of real estate properties owned as of the balance sheet date. No definition available. 
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| X | ||||||||||
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- Definition 
          The number of units in a real estate property owned as of the balance sheet date. No definition available. 
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| X | ||||||||||
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- Definition 
          The amount of ownership interest of different classes of partners in limited partnership. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Details 
          
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