Schedule III: Real estate and Accumulated depreciation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	$ 1,330,932
Initial cost of Land	22,090
Initial cost of Building, Leaseholds and Leasehold improvements	35,781
Costs capitalized subsequent to acquisition	1,004,337
Carrying amount of Land	74,974
Carring amount of Building, Leaseholds and Leasehold improvements	985,637
Construction in progress	1,597
Total carrying value of property	1,062,208
Accumulated depreciation and amortization	184,873
Differences Between Book and Tax Basis	209,775
Lexington Avenue Property [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	659,890
Initial cost of Land	14,432
Initial cost of Building, Leaseholds and Leasehold improvements	12,355
Costs capitalized subsequent to acquisition	424,823
Carrying amount of Land	27,498
Carring amount of Building, Leaseholds and Leasehold improvements	424,112
Construction in progress	0
Total carrying value of property	451,610
Accumulated depreciation and amortization	91,615
Date of construction	2003
Date acquired	1992
Depreciation in latest income statement is computed Minimum	9
Depreciation in latest income statement is computed Maximum	39
Kings Plaza Regional Shopping Center [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	250,000
Initial cost of Land	497
Initial cost of Building, Leaseholds and Leasehold improvements	9,542
Costs capitalized subsequent to acquisition	145,262
Carrying amount of Land	30,002
Carring amount of Building, Leaseholds and Leasehold improvements	124,805
Construction in progress	494
Total carrying value of property	155,301
Accumulated depreciation and amortization	48,413
Date of construction	1970
Date acquired	1992
Depreciation in latest income statement is computed Minimum	5
Depreciation in latest income statement is computed Maximum	50
Rego Park 1 Shopping [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	78,246
Initial cost of Land	1,647
Initial cost of Building, Leaseholds and Leasehold improvements	8,953
Costs capitalized subsequent to acquisition	47,361
Carrying amount of Land	1,647
Carring amount of Building, Leaseholds and Leasehold improvements	56,302
Construction in progress	12
Total carrying value of property	57,961
Accumulated depreciation and amortization	22,986
Date of construction	1959
Date acquired	1992
Depreciation in latest income statement is computed Minimum	5
Depreciation in latest income statement is computed Maximum	39
Rego Park 2 Property [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	274,796
Initial cost of Land	3,127
Initial cost of Building, Leaseholds and Leasehold improvements	1,467
Costs capitalized subsequent to acquisition	376,948
Carrying amount of Land	3,127
Carring amount of Building, Leaseholds and Leasehold improvements	378,415
Construction in progress	0
Total carrying value of property	381,542
Accumulated depreciation and amortization	21,243
Date of construction	2009
Date acquired	1992
Depreciation in latest income statement is computed Minimum	5
Depreciation in latest income statement is computed Maximum	40
Paramus Property [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	68,000
Initial cost of Land	1,441
Initial cost of Building, Leaseholds and Leasehold improvements	0
Costs capitalized subsequent to acquisition	10,313
Carrying amount of Land	11,754
Carring amount of Building, Leaseholds and Leasehold improvements	0
Construction in progress	0
Total carrying value of property	11,754
Accumulated depreciation and amortization	0
Date acquired	1992
Flushing Property [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial cost of Land	0
Initial cost of Building, Leaseholds and Leasehold improvements	1,660
Costs capitalized subsequent to acquisition	(107)
Carrying amount of Land	0
Carring amount of Building, Leaseholds and Leasehold improvements	1,553
Construction in progress	0
Total carrying value of property	1,553
Accumulated depreciation and amortization	613
Date of construction	1975
Date acquired	1992
Rego Park 3 Property [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial cost of Land	779
Initial cost of Building, Leaseholds and Leasehold improvements	0
Costs capitalized subsequent to acquisition	1,541
Carrying amount of Land	779
Carring amount of Building, Leaseholds and Leasehold improvements	450
Construction in progress	1,091
Total carrying value of property	2,320
Accumulated depreciation and amortization	3
Date acquired	1992
Depreciation in latest income statement is computed Minimum	5
Real Estate and Accumulated Depreciation, Life Used for Depreciation	15
Other Properties [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial cost of Land	167
Initial cost of Building, Leaseholds and Leasehold improvements	1,804
Costs capitalized subsequent to acquisition	(1,804)
Carrying amount of Land	167
Carring amount of Building, Leaseholds and Leasehold improvements	0
Construction in progress	0
Total carrying value of property	167
Accumulated depreciation and amortization	$ 0
Date acquired	1992