SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION Schedule of Real Estate and Accumulated Depreciation (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	1,130,101,000
Initial Cost to Company of Land	451,700,000
Initial Cost to Company of Buildings and Improvements	1,152,388,000
Costs Capitalized Subsequent to Acquisition	604,507,000
Carrying Amount of Land	478,876,000
Carrying Amount of Buildings and Improvements	1,729,719,000
Total Carrying Amount	2,208,595,000	1,819,053,000	1,287,198,000	897,370,000
Accumulated Depreciation	256,015,000	229,538,000	169,718,000	147,626,000
Real Estate, Federal Income Tax Basis	1,811,200,000
Minimum [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Life Used for Depreciation	30 years
Maximum [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Life Used for Depreciation	40 years
Core Portfolio [Member] | Crescent Plaza [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	16,455,000
Initial Cost to Company of Land	1,147,000
Initial Cost to Company of Buildings and Improvements	7,425,000
Costs Capitalized Subsequent to Acquisition	1,376,000
Carrying Amount of Land	1,147,000
Carrying Amount of Buildings and Improvements	8,801,000
Total Carrying Amount	9,948,000
Accumulated Depreciation	6,913,000
Core Portfolio [Member] | New Louden Center [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	505,000
Initial Cost to Company of Buildings and Improvements	4,161,000
Costs Capitalized Subsequent to Acquisition	13,052,000
Carrying Amount of Land	505,000
Carrying Amount of Buildings and Improvements	17,213,000
Total Carrying Amount	17,718,000
Accumulated Depreciation	13,112,000
Core Portfolio [Member] | Mark Plaza [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	0
Initial Cost to Company of Buildings and Improvements	4,268,000
Costs Capitalized Subsequent to Acquisition	(872,000)
Carrying Amount of Land	0
Carrying Amount of Buildings and Improvements	3,396,000
Total Carrying Amount	3,396,000
Accumulated Depreciation	2,783,000
Core Portfolio [Member] | Plaza 422 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	190,000
Initial Cost to Company of Buildings and Improvements	3,004,000
Costs Capitalized Subsequent to Acquisition	2,309,000
Carrying Amount of Land	190,000
Carrying Amount of Buildings and Improvements	5,313,000
Total Carrying Amount	5,503,000
Accumulated Depreciation	4,963,000
Core Portfolio [Member] | Route 6 Mall [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	1,664,000
Initial Cost to Company of Buildings and Improvements	0
Costs Capitalized Subsequent to Acquisition	12,276,000
Carrying Amount of Land	1,664,000
Carrying Amount of Buildings and Improvements	12,276,000
Total Carrying Amount	13,940,000
Accumulated Depreciation	7,624,000
Core Portfolio [Member] | Abington Towne Center [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	799,000
Initial Cost to Company of Buildings and Improvements	3,197,000
Costs Capitalized Subsequent to Acquisition	2,357,000
Carrying Amount of Land	799,000
Carrying Amount of Buildings and Improvements	5,554,000
Total Carrying Amount	6,353,000
Accumulated Depreciation	3,307,000
Core Portfolio [Member] | Bloomfield Town Square [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	3,207,000
Initial Cost to Company of Buildings and Improvements	13,774,000
Costs Capitalized Subsequent to Acquisition	21,579,000
Carrying Amount of Land	3,207,000
Carrying Amount of Buildings and Improvements	35,353,000
Total Carrying Amount	38,560,000
Accumulated Depreciation	15,511,000
Core Portfolio [Member] | Elmwood Park Plaza [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	32,201,000
Initial Cost to Company of Land	3,248,000
Initial Cost to Company of Buildings and Improvements	12,992,000
Costs Capitalized Subsequent to Acquisition	15,855,000
Carrying Amount of Land	3,798,000
Carrying Amount of Buildings and Improvements	28,297,000
Total Carrying Amount	32,095,000
Accumulated Depreciation	15,647,000
Core Portfolio [Member] | Merrillville Plaza [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	25,503,000
Initial Cost to Company of Land	4,288,000
Initial Cost to Company of Buildings and Improvements	17,152,000
Costs Capitalized Subsequent to Acquisition	5,553,000
Carrying Amount of Land	4,288,000
Carrying Amount of Buildings and Improvements	22,705,000
Total Carrying Amount	26,993,000
Accumulated Depreciation	9,400,000
Core Portfolio [Member] | Marketplace of Absecon [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	2,573,000
Initial Cost to Company of Buildings and Improvements	10,294,000
Costs Capitalized Subsequent to Acquisition	4,900,000
Carrying Amount of Land	2,577,000
Carrying Amount of Buildings and Improvements	15,190,000
Total Carrying Amount	17,767,000
Accumulated Depreciation	6,616,000
Core Portfolio [Member] | 239 Greenwich Avenue [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	26,000,000
Initial Cost to Company of Land	1,817,000
Initial Cost to Company of Buildings and Improvements	15,846,000
Costs Capitalized Subsequent to Acquisition	597,000
Carrying Amount of Land	1,817,000
Carrying Amount of Buildings and Improvements	16,443,000
Total Carrying Amount	18,260,000
Accumulated Depreciation	6,545,000
Core Portfolio [Member] | Hobson West Plaza [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	1,793,000
Initial Cost to Company of Buildings and Improvements	7,172,000
Costs Capitalized Subsequent to Acquisition	1,842,000
Carrying Amount of Land	1,793,000
Carrying Amount of Buildings and Improvements	9,014,000
Total Carrying Amount	10,807,000
Accumulated Depreciation	4,308,000
Core Portfolio [Member] | Village Commons Shopping Center [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	3,229,000
Initial Cost to Company of Buildings and Improvements	12,917,000
Costs Capitalized Subsequent to Acquisition	4,048,000
Carrying Amount of Land	3,229,000
Carrying Amount of Buildings and Improvements	16,965,000
Total Carrying Amount	20,194,000
Accumulated Depreciation	7,799,000
Core Portfolio [Member] | Town Line Plaza [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	878,000
Initial Cost to Company of Buildings and Improvements	3,510,000
Costs Capitalized Subsequent to Acquisition	7,609,000
Carrying Amount of Land	907,000
Carrying Amount of Buildings and Improvements	11,090,000
Total Carrying Amount	11,997,000
Accumulated Depreciation	8,615,000
Core Portfolio [Member] | Branch Shopping Center [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	3,156,000
Initial Cost to Company of Buildings and Improvements	12,545,000
Costs Capitalized Subsequent to Acquisition	11,457,000
Carrying Amount of Land	3,401,000
Carrying Amount of Buildings and Improvements	23,757,000
Total Carrying Amount	27,158,000
Accumulated Depreciation	7,045,000
Core Portfolio [Member] | The Methuen Shopping Center [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	956,000
Initial Cost to Company of Buildings and Improvements	3,826,000
Costs Capitalized Subsequent to Acquisition	594,000
Carrying Amount of Land	961,000
Carrying Amount of Buildings and Improvements	4,415,000
Total Carrying Amount	5,376,000
Accumulated Depreciation	2,070,000
Core Portfolio [Member] | The Gateway Shopping Center [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	19,440,000
Initial Cost to Company of Land	1,273,000
Initial Cost to Company of Buildings and Improvements	5,091,000
Costs Capitalized Subsequent to Acquisition	12,258,000
Carrying Amount of Land	1,273,000
Carrying Amount of Buildings and Improvements	17,349,000
Total Carrying Amount	18,622,000
Accumulated Depreciation	7,608,000
Core Portfolio [Member] | Mad River Station [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	2,350,000
Initial Cost to Company of Buildings and Improvements	9,404,000
Costs Capitalized Subsequent to Acquisition	1,149,000
Carrying Amount of Land	2,350,000
Carrying Amount of Buildings and Improvements	10,553,000
Total Carrying Amount	12,903,000
Accumulated Depreciation	4,590,000
Core Portfolio [Member] | Pacesetter Park Shopping Center [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	11,307,000
Initial Cost to Company of Land	1,475,000
Initial Cost to Company of Buildings and Improvements	5,899,000
Costs Capitalized Subsequent to Acquisition	2,235,000
Carrying Amount of Land	1,475,000
Carrying Amount of Buildings and Improvements	8,134,000
Total Carrying Amount	9,609,000
Accumulated Depreciation	3,757,000
Core Portfolio [Member] | Brandywine Town Center [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	141,825,000
Initial Cost to Company of Land	21,993,000
Initial Cost to Company of Buildings and Improvements	87,988,000
Costs Capitalized Subsequent to Acquisition	16,329,000
Carrying Amount of Land	24,213,000
Carrying Amount of Buildings and Improvements	102,097,000
Total Carrying Amount	126,310,000
Accumulated Depreciation	28,808,000
Core Portfolio [Member] | Brandywine Market Square [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	24,375,000
Initial Cost to Company of Land	4,308,000
Initial Cost to Company of Buildings and Improvements	17,239,000
Costs Capitalized Subsequent to Acquisition	970,000
Carrying Amount of Land	4,262,000
Carrying Amount of Buildings and Improvements	18,255,000
Total Carrying Amount	22,517,000
Accumulated Depreciation	5,916,000
Core Portfolio [Member] | Bartow Avenue [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	1,691,000
Initial Cost to Company of Buildings and Improvements	5,803,000
Costs Capitalized Subsequent to Acquisition	638,000
Carrying Amount of Land	1,691,000
Carrying Amount of Buildings and Improvements	6,441,000
Total Carrying Amount	8,132,000
Accumulated Depreciation	2,310,000
Core Portfolio [Member] | Amboy Rd. Shopping Ctr. [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	0
Initial Cost to Company of Buildings and Improvements	11,909,000
Costs Capitalized Subsequent to Acquisition	2,514,000
Carrying Amount of Land	0
Carrying Amount of Buildings and Improvements	14,423,000
Total Carrying Amount	14,423,000
Accumulated Depreciation	4,306,000
Core Portfolio [Member] | 613-623 West Diversey [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	10,061,000
Initial Cost to Company of Buildings and Improvements	2,773,000
Costs Capitalized Subsequent to Acquisition	355,000
Carrying Amount of Land	10,061,000
Carrying Amount of Buildings and Improvements	3,128,000
Total Carrying Amount	13,189,000
Accumulated Depreciation	793,000
Core Portfolio [Member] | Chestnut Hill [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	8,289,000
Initial Cost to Company of Buildings and Improvements	5,691,000
Costs Capitalized Subsequent to Acquisition	4,242,000
Carrying Amount of Land	8,289,000
Carrying Amount of Buildings and Improvements	9,933,000
Total Carrying Amount	18,222,000
Accumulated Depreciation	2,143,000
Core Portfolio [Member] | Third Avenue [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	11,108,000
Initial Cost to Company of Buildings and Improvements	8,038,000
Costs Capitalized Subsequent to Acquisition	4,397,000
Carrying Amount of Land	11,855,000
Carrying Amount of Buildings and Improvements	11,688,000
Total Carrying Amount	23,543,000
Accumulated Depreciation	1,851,000
Core Portfolio [Member] | West Shore Expressway [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	3,380,000
Initial Cost to Company of Buildings and Improvements	13,554,000
Costs Capitalized Subsequent to Acquisition	(55,000)
Carrying Amount of Land	3,380,000
Carrying Amount of Buildings and Improvements	13,499,000
Total Carrying Amount	16,879,000
Accumulated Depreciation	2,969,000
Core Portfolio [Member] | West 54th Street [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	16,699,000
Initial Cost to Company of Buildings and Improvements	18,704,000
Costs Capitalized Subsequent to Acquisition	949,000
Carrying Amount of Land	16,699,000
Carrying Amount of Buildings and Improvements	19,653,000
Total Carrying Amount	36,352,000
Accumulated Depreciation	3,692,000
Core Portfolio [Member] | Acadia 5-7 East 17th Street [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	3,048,000
Initial Cost to Company of Buildings and Improvements	7,281,000
Costs Capitalized Subsequent to Acquisition	376,000
Carrying Amount of Land	3,048,000
Carrying Amount of Buildings and Improvements	7,657,000
Total Carrying Amount	10,705,000
Accumulated Depreciation	1,321,000
Core Portfolio [Member] | West Diversey 651-671 W Diversey [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	8,576,000
Initial Cost to Company of Buildings and Improvements	17,256,000
Costs Capitalized Subsequent to Acquisition	8,000
Carrying Amount of Land	8,576,000
Carrying Amount of Buildings and Improvements	17,264,000
Total Carrying Amount	25,840,000
Accumulated Depreciation	1,546,000
Core Portfolio [Member] | Mercer Street 15 Mercer Street [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	1,887,000
Initial Cost to Company of Buildings and Improvements	2,483,000
Costs Capitalized Subsequent to Acquisition	7,000
Carrying Amount of Land	1,887,000
Carrying Amount of Buildings and Improvements	2,490,000
Total Carrying Amount	4,377,000
Accumulated Depreciation	217,000
Core Portfolio [Member] | 4401 White Plains [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	6,141,000
Initial Cost to Company of Land	1,581,000
Initial Cost to Company of Buildings and Improvements	5,054,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	1,581,000
Carrying Amount of Buildings and Improvements	5,054,000
Total Carrying Amount	6,635,000
Accumulated Depreciation	421,000
Core Portfolio [Member] | Chicago Street Retail Portfolio [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	15,485,000
Initial Cost to Company of Land	18,521,000
Initial Cost to Company of Buildings and Improvements	55,627,000
Costs Capitalized Subsequent to Acquisition	1,576,000
Carrying Amount of Land	18,559,000
Carrying Amount of Buildings and Improvements	57,165,000
Total Carrying Amount	75,724,000
Accumulated Depreciation	3,692,000
Core Portfolio [Member] | 330 River Street [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	3,974,000
Initial Cost to Company of Land	3,510,000
Initial Cost to Company of Buildings and Improvements	2,886,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	3,510,000
Carrying Amount of Buildings and Improvements	2,886,000
Total Carrying Amount	6,396,000
Accumulated Depreciation	237,000
Core Portfolio [Member] | Rhode Island Place Shopping Center [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	16,560,000
Initial Cost to Company of Land	7,458,000
Initial Cost to Company of Buildings and Improvements	15,968,000
Costs Capitalized Subsequent to Acquisition	158,000
Carrying Amount of Land	7,458,000
Carrying Amount of Buildings and Improvements	16,126,000
Total Carrying Amount	23,584,000
Accumulated Depreciation	1,141,000
Core Portfolio [Member] | 1520 North Milwaukee Avenue [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	2,110,000
Initial Cost to Company of Buildings and Improvements	1,306,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	2,110,000
Carrying Amount of Buildings and Improvements	1,306,000
Total Carrying Amount	3,416,000
Accumulated Depreciation	155,000
Core Portfolio [Member] | 340 River Street [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	6,820,000
Initial Cost to Company of Land	4,894,000
Initial Cost to Company of Buildings and Improvements	11,349,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	4,894,000
Carrying Amount of Buildings and Improvements	11,349,000
Total Carrying Amount	16,243,000
Accumulated Depreciation	840,000
Core Portfolio [Member] | 930 Rush Street [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	4,933,000
Initial Cost to Company of Buildings and Improvements	14,587,000
Costs Capitalized Subsequent to Acquisition	11,000
Carrying Amount of Land	4,933,000
Carrying Amount of Buildings and Improvements	14,598,000
Total Carrying Amount	19,531,000
Accumulated Depreciation	1,003,000
Core Portfolio [Member] | 28 Jericho Turnpike [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	15,747,000
Initial Cost to Company of Land	6,220,000
Initial Cost to Company of Buildings and Improvements	24,416,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	6,220,000
Carrying Amount of Buildings and Improvements	24,416,000
Total Carrying Amount	30,636,000
Accumulated Depreciation	1,654,000
Core Portfolio [Member] | 181 Main Street [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	1,908,000
Initial Cost to Company of Buildings and Improvements	12,158,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	1,908,000
Carrying Amount of Buildings and Improvements	12,158,000
Total Carrying Amount	14,066,000
Accumulated Depreciation	644,000
Core Portfolio [Member] | 83 Spring Street [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	1,754,000
Initial Cost to Company of Buildings and Improvements	9,200,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	1,754,000
Carrying Amount of Buildings and Improvements	9,200,000
Total Carrying Amount	10,954,000
Accumulated Depreciation	575,000
Core Portfolio [Member] | 60 Orange Street [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	8,236,000
Initial Cost to Company of Land	3,609,000
Initial Cost to Company of Buildings and Improvements	10,790,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	3,609,000
Carrying Amount of Buildings and Improvements	10,790,000
Total Carrying Amount	14,399,000
Accumulated Depreciation	669,000
Core Portfolio [Member] | 171-53 and 181-03 Connecticut Avenue [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	11,690,000
Initial Cost to Company of Buildings and Improvements	10,135,000
Costs Capitalized Subsequent to Acquisition	318,000
Carrying Amount of Land	11,689,000
Carrying Amount of Buildings and Improvements	10,454,000
Total Carrying Amount	22,143,000
Accumulated Depreciation	579,000
Core Portfolio [Member] | 639 West Diversey [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	4,480,000
Initial Cost to Company of Land	4,429,000
Initial Cost to Company of Buildings and Improvements	6,102,000
Costs Capitalized Subsequent to Acquisition	313,000
Carrying Amount of Land	4,429,000
Carrying Amount of Buildings and Improvements	6,415,000
Total Carrying Amount	10,844,000
Accumulated Depreciation	332,000
Core Portfolio [Member] | 664 North Michigan Avenue [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	44,369,000
Initial Cost to Company of Land	15,240,000
Initial Cost to Company of Buildings and Improvements	65,331,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	15,240,000
Carrying Amount of Buildings and Improvements	65,331,000
Total Carrying Amount	80,571,000
Accumulated Depreciation	3,089,000
Core Portfolio [Member] | 8-12 East Walton [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	5,398,000
Initial Cost to Company of Buildings and Improvements	15,601,000
Costs Capitalized Subsequent to Acquisition	22,000
Carrying Amount of Land	5,398,000
Carrying Amount of Buildings and Improvements	15,623,000
Total Carrying Amount	21,021,000
Accumulated Depreciation	626,000
Core Portfolio [Member] | 3200 - 3204 M Street [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	6,899,000
Initial Cost to Company of Buildings and Improvements	4,249,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	6,899,000
Carrying Amount of Buildings and Improvements	4,249,000
Total Carrying Amount	11,148,000
Accumulated Depreciation	133,000
Core Portfolio [Member] | 868 Broadway [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	3,519,000
Initial Cost to Company of Buildings and Improvements	9,247,000
Costs Capitalized Subsequent to Acquisition	5,000
Carrying Amount of Land	3,519,000
Carrying Amount of Buildings and Improvements	9,252,000
Total Carrying Amount	12,771,000
Accumulated Depreciation	248,000
Core Portfolio [Member] | 313 - 315 Bowery [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	0
Initial Cost to Company of Buildings and Improvements	5,516,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	0
Carrying Amount of Buildings and Improvements	5,516,000
Total Carrying Amount	5,516,000
Accumulated Depreciation	223,000
Core Portfolio [Member] | 120 West Broadway [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	0
Initial Cost to Company of Buildings and Improvements	32,819,000
Costs Capitalized Subsequent to Acquisition	20,000
Carrying Amount of Land	0
Carrying Amount of Buildings and Improvements	32,839,000
Total Carrying Amount	32,839,000
Accumulated Depreciation	497,000
Core Portfolio [Member] | 11 East Walton [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	11,000,000
Initial Cost to Company of Buildings and Improvements	33,000,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	11,000,000
Carrying Amount of Buildings and Improvements	33,000,000
Total Carrying Amount	44,000,000
Accumulated Depreciation	756,000
Core Portfolio [Member] | 61 Main Street [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	1,825,000
Initial Cost to Company of Buildings and Improvements	5,505,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	1,825,000
Carrying Amount of Buildings and Improvements	5,505,000
Total Carrying Amount	7,330,000
Accumulated Depreciation	114,000
Core Portfolio [Member] | 865 W. North Avenue [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	3,688,000
Initial Cost to Company of Buildings and Improvements	11,063,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	3,688,000
Carrying Amount of Buildings and Improvements	11,063,000
Total Carrying Amount	14,751,000
Accumulated Depreciation	230,000
Core Portfolio [Member] | 152 - 154 Spring Street [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	9,500,000
Initial Cost to Company of Buildings and Improvements	28,500,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	9,500,000
Carrying Amount of Buildings and Improvements	28,500,000
Total Carrying Amount	38,000,000
Accumulated Depreciation	475,000
Core Portfolio [Member] | 2520 Flatbush Avenue [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	4,275,000
Initial Cost to Company of Buildings and Improvements	12,825,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	4,275,000
Carrying Amount of Buildings and Improvements	12,825,000
Total Carrying Amount	17,100,000
Accumulated Depreciation	187,000
Core Portfolio [Member] | 252 - 254 Greenwich Avenue [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	6,113,000
Initial Cost to Company of Buildings and Improvements	18,378,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	6,113,000
Carrying Amount of Buildings and Improvements	18,378,000
Total Carrying Amount	24,491,000
Accumulated Depreciation	344,000
Core Portfolio [Member] | Bedford Green [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	31,363,000
Initial Cost to Company of Land	13,788,000
Initial Cost to Company of Buildings and Improvements	35,153,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	13,788,000
Carrying Amount of Buildings and Improvements	35,153,000
Total Carrying Amount	48,941,000
Accumulated Depreciation	450,000
Core Portfolio [Member] | 131 - 135 Prince Street [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	19,274,000
Initial Cost to Company of Buildings and Improvements	38,519,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	19,274,000
Carrying Amount of Buildings and Improvements	38,519,000
Total Carrying Amount	57,793,000
Accumulated Depreciation	321,000
Core Portfolio [Member] | Shops At Grand Avenue [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	14,000,000
Initial Cost to Company of Buildings and Improvements	42,000,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	14,000,000
Carrying Amount of Buildings and Improvements	42,000,000
Total Carrying Amount	56,000,000
Accumulated Depreciation	263,000
Core Portfolio [Member] | 201 Needham Street [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	2,531,000
Initial Cost to Company of Buildings and Improvements	7,594,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	2,531,000
Carrying Amount of Buildings and Improvements	7,594,000
Total Carrying Amount	10,125,000
Accumulated Depreciation	16,000
Core Portfolio [Member] | Undeveloped Land [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	100,000
Initial Cost to Company of Buildings and Improvements	0
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	100,000
Carrying Amount of Buildings and Improvements	0
Total Carrying Amount	100,000
Accumulated Depreciation	0
Core Portfolio [Member] | ARLP [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	50,000,000
Initial Cost to Company of Land	0
Initial Cost to Company of Buildings and Improvements	0
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	0
Carrying Amount of Buildings and Improvements	0
Total Carrying Amount	0
Accumulated Depreciation	0
Fund I [Member] | Kroger/Safeway Various [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	0
Initial Cost to Company of Buildings and Improvements	4,215,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	0
Carrying Amount of Buildings and Improvements	4,215,000
Total Carrying Amount	4,215,000
Accumulated Depreciation	4,027,000
Fund II [Member] | Liberty Avenue [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	8,973,000
Initial Cost to Company of Land	0
Initial Cost to Company of Buildings and Improvements	12,627,000
Costs Capitalized Subsequent to Acquisition	647,000
Carrying Amount of Land	0
Carrying Amount of Buildings and Improvements	13,274,000
Total Carrying Amount	13,274,000
Accumulated Depreciation	3,060,000
Fund II [Member] | City Point [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	0
Initial Cost to Company of Buildings and Improvements	0
Costs Capitalized Subsequent to Acquisition	7,473,000
Carrying Amount of Land	0
Carrying Amount of Buildings and Improvements	7,473,000
Total Carrying Amount	7,473,000
Accumulated Depreciation	186,000
Fund II [Member] | 161st Street [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	29,500,000
Initial Cost to Company of Land	16,679,000
Initial Cost to Company of Buildings and Improvements	28,410,000
Costs Capitalized Subsequent to Acquisition	18,231,000
Carrying Amount of Land	16,679,000
Carrying Amount of Buildings and Improvements	46,641,000
Total Carrying Amount	63,320,000
Accumulated Depreciation	9,494,000
Fund III [Member] | Cortlandt Towne Center [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	83,936,000
Initial Cost to Company of Land	7,293,000
Initial Cost to Company of Buildings and Improvements	61,395,000
Costs Capitalized Subsequent to Acquisition	9,213,000
Carrying Amount of Land	7,293,000
Carrying Amount of Buildings and Improvements	70,608,000
Total Carrying Amount	77,901,000
Accumulated Depreciation	17,637,000
Fund III [Member] | Heritage Shops [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	24,500,000
Initial Cost to Company of Land	13,131,000
Initial Cost to Company of Buildings and Improvements	15,409,000
Costs Capitalized Subsequent to Acquisition	386,000
Carrying Amount of Land	13,131,000
Carrying Amount of Buildings and Improvements	15,795,000
Total Carrying Amount	28,926,000
Accumulated Depreciation	2,012,000
Fund III [Member] | 654 Broadway [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	9,000,000
Initial Cost to Company of Land	9,040,000
Initial Cost to Company of Buildings and Improvements	3,654,000
Costs Capitalized Subsequent to Acquisition	1,435,000
Carrying Amount of Land	9,040,000
Carrying Amount of Buildings and Improvements	5,089,000
Total Carrying Amount	14,129,000
Accumulated Depreciation	352,000
Fund III [Member] | New Hyde Park Shopping Center [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	11,720,000
Initial Cost to Company of Land	3,016,000
Initial Cost to Company of Buildings and Improvements	7,733,000
Costs Capitalized Subsequent to Acquisition	4,019,000
Carrying Amount of Land	3,016,000
Carrying Amount of Buildings and Improvements	11,752,000
Total Carrying Amount	14,768,000
Accumulated Depreciation	1,050,000
Fund III [Member] | 640 Broadway [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	22,564,000
Initial Cost to Company of Land	12,503,000
Initial Cost to Company of Buildings and Improvements	19,960,000
Costs Capitalized Subsequent to Acquisition	6,430,000
Carrying Amount of Land	12,503,000
Carrying Amount of Buildings and Improvements	26,390,000
Total Carrying Amount	38,893,000
Accumulated Depreciation	1,814,000
Fund III [Member] | Lincoln Park Centre LLC [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	28,000,000
Initial Cost to Company of Land	0
Initial Cost to Company of Buildings and Improvements	0
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	0
Carrying Amount of Buildings and Improvements	0
Total Carrying Amount	0
Accumulated Depreciation	0
Fund III [Member] | 3780 to 3858 Nortrand Avenue [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	12,047,000
Initial Cost to Company of Land	6,229,000
Initial Cost to Company of Buildings and Improvements	11,216,000
Costs Capitalized Subsequent to Acquisition	3,128,000
Carrying Amount of Land	6,229,000
Carrying Amount of Buildings and Improvements	14,344,000
Total Carrying Amount	20,573,000
Accumulated Depreciation	594,000
Fund IV [Member] | 210 Bowery LLC [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	4,600,000
Initial Cost to Company of Land	1,875,000
Initial Cost to Company of Buildings and Improvements	5,625,000
Costs Capitalized Subsequent to Acquisition	22,000
Carrying Amount of Land	1,875,000
Carrying Amount of Buildings and Improvements	5,647,000
Total Carrying Amount	7,522,000
Accumulated Depreciation	281,000
Fund IV [Member] | Paramus Plaza [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	12,600,000
Initial Cost to Company of Land	11,052,000
Initial Cost to Company of Buildings and Improvements	7,037,000
Costs Capitalized Subsequent to Acquisition	1,852,000
Carrying Amount of Land	11,052,000
Carrying Amount of Buildings and Improvements	8,889,000
Total Carrying Amount	19,941,000
Accumulated Depreciation	272,000
Fund IV [Member] | 1151 Third Avenue [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	12,481,000
Initial Cost to Company of Land	8,306,000
Initial Cost to Company of Buildings and Improvements	9,685,000
Costs Capitalized Subsequent to Acquisition	978,000
Carrying Amount of Land	8,306,000
Carrying Amount of Buildings and Improvements	10,663,000
Total Carrying Amount	18,969,000
Accumulated Depreciation	321,000
Fund IV [Member] | Lake Montclair [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	15,284,000
Initial Cost to Company of Land	7,077,000
Initial Cost to Company of Buildings and Improvements	12,028,000
Costs Capitalized Subsequent to Acquisition	25,000
Carrying Amount of Land	7,077,000
Carrying Amount of Buildings and Improvements	12,053,000
Total Carrying Amount	19,130,000
Accumulated Depreciation	381,000
Fund IV [Member] | 938 West North Avenue [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	12,500,000
Initial Cost to Company of Land	2,314,000
Initial Cost to Company of Buildings and Improvements	17,067,000
Costs Capitalized Subsequent to Acquisition	34,000
Carrying Amount of Land	2,314,000
Carrying Amount of Buildings and Improvements	17,101,000
Total Carrying Amount	19,415,000
Accumulated Depreciation	449,000
Fund IV [Member] | 17 E. 71st Street [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to Company of Land	7,000,000
Initial Cost to Company of Buildings and Improvements	21,000,000
Costs Capitalized Subsequent to Acquisition	0
Carrying Amount of Land	7,000,000
Carrying Amount of Buildings and Improvements	21,000,000
Total Carrying Amount	28,000,000
Accumulated Depreciation	86,000
Fund IV [Member] | Real Estate Under Development [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	265,015,000
Initial Cost to Company of Land	30,830,000
Initial Cost to Company of Buildings and Improvements	19,253,000
Costs Capitalized Subsequent to Acquisition	397,307,000
Carrying Amount of Land	54,215,000
Carrying Amount of Buildings and Improvements	393,175,000
Total Carrying Amount	447,390,000
Accumulated Depreciation	0