| Mortgages, Loans Payable And Other Obligations (Summary Of Mortgages, Loans Payable And Other Obligations) (Details) (USD $) | 9 Months Ended | 9 Months Ended | 9 Months Ended | 9 Months Ended | 9 Months Ended | 9 Months Ended | 9 Months Ended | 9 Months Ended | 9 Months Ended | 9 Months Ended | 9 Months Ended | 9 Months Ended | 9 Months Ended | 9 Months Ended | 9 Months Ended | 9 Months Ended | 9 Months Ended | 9 Months Ended | 9 Months Ended | 9 Months Ended | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Sep. 30, 2013 | Sep. 30, 2014 | Dec. 31, 2013 | Sep. 30, 2014
 6301 Ivy Lane [Member] | Dec. 31, 2013
 6301 Ivy Lane [Member] | Sep. 30, 2014
 395 West Passaic [Member] | Dec. 31, 2013
 395 West Passaic [Member] | Sep. 30, 2014
 35 Waterview Boulevard [Member] | Dec. 31, 2013
 35 Waterview Boulevard [Member] | Sep. 30, 2014
 233 Canoe Brook Road [Member] | Dec. 31, 2013
 233 Canoe Brook Road [Member] | Sep. 30, 2014
 6 Becker, 85 Livingston, 75 Livingston & 20 Waterview [Member]
 property | Dec. 31, 2013
 6 Becker, 85 Livingston, 75 Livingston & 20 Waterview [Member] | Sep. 30, 2014
 4 Sylvan [Member] | Dec. 31, 2013
 4 Sylvan [Member] | Sep. 30, 2014
 10 Independence [Member] | Dec. 31, 2013
 10 Independence [Member] | Sep. 30, 2014
 Port Imperial South 4/5 [Member] | Dec. 31, 2013
 Port Imperial South 4/5 [Member] | Sep. 30, 2014
 Overlook - Site IIID, IIIC, IIIA [Member] | Sep. 30, 2014
 Overlook - Site IIIB [Member] | Sep. 30, 2014
 9200 Edmonston Road [Member] | Dec. 31, 2013
 9200 Edmonston Road [Member] | Sep. 30, 2014
 Port Imperial South [Member] | Dec. 31, 2013
 Port Imperial South [Member] | Sep. 30, 2014
 4 Becker [Member] | Dec. 31, 2013
 4 Becker [Member] | Sep. 30, 2014
 5 Becker [Member] | Dec. 31, 2013
 5 Becker [Member] | Sep. 30, 2014
 210 Clay [Member] | Dec. 31, 2013
 210 Clay [Member] | Sep. 30, 2014
 Curtis Center [Member]
 item | Sep. 30, 2014
 Curtis Center [Member]
 Senior Loan [Member] | Sep. 30, 2014
 Curtis Center [Member]
 Mezzanine Loan [Member] | Sep. 30, 2014
 Various [Member]
 property | Dec. 31, 2013
 Various [Member] | Sep. 30, 2014
 150 Main St [Member] | Sep. 30, 2014
 23 Main Street [Member] | Dec. 31, 2013
 23 Main Street [Member] | Sep. 30, 2014
 Harborside Plaza 5 [Member] | Dec. 31, 2013
 Harborside Plaza 5 [Member] | Sep. 30, 2014
 100 Walnut Avenue [Member] | Dec. 31, 2013
 100 Walnut Avenue [Member] | Sep. 30, 2014
 One River Center [Member]
 property | Dec. 31, 2013
 One River Center [Member] | Sep. 30, 2014
 Park Square [Member] | Sep. 30, 2014
 Consolidated Land [Member]
 Overlook Ridge Properties [Member] | Aug. 15, 2014
 Consolidated Land [Member]
 Overlook Ridge Properties [Member] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Debt Instrument [Line Items] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Property Name | 6301 Ivy Lane (b) | [1] | 395 West Passaic (c) | [2] | 35 Waterview Boulevard (d) | [3] | 233 Canoe Brook Road (e) | [4] | 6 Becker, 85 Livingston, 75 Livingston & 20 Waterview | [5] | 4 Sylvan | 10 Independence (g) | [6] | Port Imperial South 4/5 | Overlook - Site IIID,IIIC, IIIA (p) | [7] | Overlook - Site IIB (Quarrystone I) (p) | [7] | 9200 Edmonston Road (h) | [8] | Port Imperial South | 4 Becker | 5 Becker (i) | [9] | 210 Clay | Curtis Center (j) | [10] | Various (k) | [11] | 150 Main St. | 23 Main Street | Harborside Plaza 5 | 100 Walnut Avenue | One River Center (l) | [12] | Park Square | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Lender | RGA Reinsurance Company | [1] | State Farm Life Insurance Co. | [2] | Wells Fargo CMBS | [3] | The Provident Bank | [4] | Wells Fargo CMBS | [5] | Wells Fargo CMBS | Wells Fargo CMBS | [6] | Wells Fargo Bank N.A. | Wells Fargo Bank N.A. | [7] | Wells Fargo Bank N.A. | [7] | Principal Commercial Funding L.L.C. | [8] | Wells Fargo Bank N.A. | Wells Fargo CMBS | Wells Fargo CMBS | [9] | Wells Fargo CMBS | CCRE & PREFG | [10] | Prudential Insurance | [11] | Webster Bank | JPMorgan CMBS | The Northwestern Mutual Life Insurance Co. & New York Life Insurance Co. | Guardian Life Insurance Co. | Guardian Life Insurance Co. | [12] | Wells Fargo Bank N.A. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| LIBOR | LIBOR+3.50 | [13] | LIBOR+3.50 | [13],[7] | LIBOR+2.50 | [13],[7] | LIBOR+1.75 | [13] | LIBOR+4.55 | [10],[13],[14] | LIBOR+2.35 | [13] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Effective Rate | 5.52% | [1],[13] | 6.004% | [13],[2] | 6.348% | [13],[3] | 4.375% | [13],[4] | 10.22% | [13],[5] | 10.19% | [13] | 12.44% | [13],[6] | 5.534% | [13],[8] | 9.55% | [13] | 12.83% | [13],[9] | 13.42% | [13] | 3.45% | 9.65% | 6.332% | [11],[13] | 5.587% | [13] | 6.842% | [13] | 7.311% | [13] | 7.311% | [12],[13] | 1.75% | [13],[15] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Property Debt, Interest Rate, Spread Over LIBOR | 3.50% | [13],[16] | 3.50% | [13],[7] | 2.50% | [13],[7] | 1.75% | [13] | 4.55% | [10],[13],[14] | 3.29% | 9.50% | 2.35% | [13] | 1.75% | [13],[15] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mortgages, loans payable and other obligations | $ 821,202,000 | $ 746,191,000 | [1] | $ 5,447,000 | [1] | [2] | $ 9,719,000 | [2] | [3] | $ 18,417,000 | [3] | [4] | $ 3,877,000 | [4] | $ 65,035,000 | [5] | $ 64,233,000 | [5] | $ 14,575,000 | $ 14,538,000 | $ 16,924,000 | [6] | $ 16,638,000 | [6] | $ 36,950,000 | $ 36,950,000 | $ 17,100,000 | [7] | $ 5,748,000 | [7] | $ 3,996,000 | [8] | $ 4,115,000 | [8] | $ 43,910,000 | $ 43,278,000 | $ 39,268,000 | $ 38,820,000 | $ 13,666,000 | [9] | $ 13,092,000 | [9] | $ 13,182,000 | $ 12,767,000 | $ 64,000,000 | [10] | $ 102,000,000 | $ 26,000,000 | $ 146,048,000 | [11] | $ 147,477,000 | [11] | $ 218,000 | $ 29,373,000 | $ 29,843,000 | $ 222,480,000 | $ 225,139,000 | $ 18,606,000 | $ 18,792,000 | $ 42,623,000 | [12] | $ 43,049,000 | [12] | $ 27,500,000 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Maturity | Aug. 11, 2014 | [17],[5] | Aug. 11, 2014 | [17] | Aug. 11, 2014 | [6] | Oct. 31, 2014 | [16] | Mar. 02, 2015 | [7] | Apr. 14, 2015 | [7] | May 01, 2015 | [8] | Sep. 19, 2015 | May 11, 2016 | May 11, 2016 | [9] | May 11, 2016 | Oct. 09, 2016 | [10] | Jan. 15, 2017 | [11] | Mar. 30, 2017 | Sep. 01, 2018 | Nov. 01, 2018 | Feb. 01, 2019 | Feb. 01, 2019 | [12] | Apr. 10, 2019 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Loss from early extinguishment of debt | 703,000 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Number of properties used to collateralized mortgage | 4 | 7 | 3 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Percentage of interest in venture | [18] | 50.00% | 50.00% | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Maximum borrowing capacity | $ 48,000,000 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| LIBOR measurement period | 1 month | 1 month | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Number of extension options | 3 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Loan extension period | 1 year | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Deferred financing costs amortization interest rate | 1.523% | 0.122% | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Percentage of interest in developable land | 100.00% | 100.00% | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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