Organization (Details) (USD $)	12 Months Ended
	Dec. 31, 2012 segment property
Operating Properties [Abstract]
Number of properties in greater New York City metropolitan area	6
Number Of Operating Segments	1
731 Lexington Avenue [Member]
Operating Properties [Abstract]
Area of property	1,307,000
731 Lexington Avenue [Member] | Office Space [Member]
Operating Properties [Abstract]
Area of property	885,000
731 Lexington Avenue [Member] | Office Space [Member] | Tenant Occupant [Member] | Bloomberg [Member]
Operating Properties [Abstract]
Area of property	885,000
731 Lexington Avenue [Member] | Retail Space [Member]
Operating Properties [Abstract]
Area of property	174,000
731 Lexington Avenue [Member] | Retail Space [Member] | Tenant Occupant [Member] | Container Store [Member]
Operating Properties [Abstract]
Area of property	34,000
731 Lexington Avenue [Member] | Retail Space [Member] | Tenant Occupant [Member] | Hennes Mauritz [Member]
Operating Properties [Abstract]
Area of property	27,000
731 Lexington Avenue [Member] | Retail Space [Member] | Tenant Occupant [Member] | Home Depot [Member]
Operating Properties [Abstract]
Area of property	83,000
731 Lexington Avenue [Member] | Residential Space [Member]
Operating Properties [Abstract]
Number Of Residential Units Sold	105
Area of property	248,000
Rego Park I [Member]
Operating Properties [Abstract]
Area of property	343,000
Rego Park I [Member] | Tenant Occupant [Member] | Burlington Coat Factory [Member] | Anchor [Member]
Operating Properties [Abstract]
Area of property	50,000
Rego Park I [Member] | Tenant Occupant [Member] | Marshalls [Member] | Anchor [Member]
Operating Properties [Abstract]
Area of property	36,000
Rego Park I [Member] | Tenant Occupant [Member] | Bed Bath Beyond [Member] | Anchor [Member]
Operating Properties [Abstract]
Area of property	46,000
Rego Park I [Member] | Tenant Occupant [Member] | Sears [Member] | Anchor [Member]
Operating Properties [Abstract]
Area of property	195,000
Rego Park II [Member]
Operating Properties [Abstract]
Area of property	610,000
Rego Park II [Member] | Tenant Occupant [Member] | Toys R Us [Member]
Operating Properties [Abstract]
Related Party Ownership In Tenant	one-third
Rego Park II [Member] | Tenant Occupant [Member] | Toys R Us [Member] | Anchor [Member]
Operating Properties [Abstract]
Area of property	47,000
Rego Park II [Member] | Tenant Occupant [Member] | Kohls [Member] | Anchor [Member]
Operating Properties [Abstract]
Area of property	133,000
Rego Park II [Member] | Tenant Occupant [Member] | Century 21 [Member] | Anchor [Member]
Operating Properties [Abstract]
Area of property	135,000
Rego Park II [Member] | Tenant Occupant [Member] | Costco [Member] | Anchor [Member]
Operating Properties [Abstract]
Area of property	145,000
Rego Park II [Member] | Apartment Tower [Member] | Properties to be developed [Member]
Operating Properties [Abstract]
Area of property	250,000
Approximate Number Of Apartment Units	300
Rego Park II [Member] | Apartment Tower [Member] | Maximum [Member] | Properties to be developed [Member]
Operating Properties [Abstract]
Estimated future funding	120,000,000
Rego Park II [Member] | Apartment Tower [Member] | Minimum [Member] | Properties to be developed [Member]
Operating Properties [Abstract]
Estimated future funding	100,000,000
Paramus [Member] | Tenant Occupant [Member] | Ikea [Member]
Operating Properties [Abstract]
Area Of Land	30.3
Flushing [Member] | Tenant Occupant [Member] | New World Mall Llc [Member]
Operating Properties [Abstract]
Area of property	167,000
Rego Park III [Member] | Property To Be Developed [Member]
Operating Properties [Abstract]
Area Of Land	3.4