Relationship with Vornado: Summary of Fees (Details) (Affiliated Entity [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Related Party Transaction [Line Items]
Fees to Related Party (in US Dollars)	$ 1,889	$ 3,218	$ 3,852	$ 6,046
Company Management Fees [Member]
Related Party Transaction [Line Items]
Fees to Related Party (in US Dollars)	700	750	1,400	1,500
Development fees [Member]
Related Party Transaction [Line Items]
Fees to Related Party (in US Dollars)	0	187	0	375
Leasing Fees [Member]
Related Party Transaction [Line Items]
Fees to Related Party (in US Dollars)	292	1,006	678	1,629
Property Management Fees [Member]
Related Party Transaction [Line Items]
Fees to Related Party (in US Dollars)	$ 897	$ 1,275	$ 1,774	$ 2,542