Net Loss on Disposition of Partial Interest in Development Project (Details Textuals) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Significant Acquisitions and Disposals [Line Items]
Net loss on disposition of partial interest in development project	$ 19,590,000	$ 0	$ 19,590,000	$ 0
Greenland Joint Venture [Member]
Significant Acquisitions and Disposals [Line Items]
Percentage of ownership sold	70.00%		70.00%
Cash purchase price received, net of transaction costs	163,660,000		163,660,000
Percentage of cash purchase price received, net of transaction costs	80.00%		80.00%
Remaining cash purchase price to be received	42,991,000		42,991,000
Number of days payable after closing for remaining purchase price	90 days
Net loss on disposition of partial interest in development project	19,590,000		19,590,000
Net loss on disposition of partial interest in development project, net of noncontrolling interests	$ 16,211,000		$ 16,211,000
Pacific Park Brooklyn [Member] | Greenland Joint Venture [Member]
Significant Acquisitions and Disposals [Line Items]
Area of project in acres	22		22