Investment in 111 West 57th Partners LLC (Details) (USD $)	3 Months Ended			9 Months Ended
	Sep. 30, 2014 Agreement sqft	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2014 Agreement sqft	Dec. 31, 2013
Investment in 111 West 57th Partners LLC [Abstract]
Amount of the investment	$ 56,000,000			$ 56,000,000
Percentage ownership (in hundredths)	59.00%			59.00%
Additional indirect contribution	1,250,000			1,250,000
Additional ownership acquired through indirect contribution (in hundredths)	1.30%			1.30%
Additional contributions made by other partners in the agreement	37,750,000			37,750,000
Description of partnership agreement distribution				The JV Agreement and related operating agreements generally provide that all distributable cash shall be distributed as follows: (i) first, 100% to the members in proportion to their percentage interests until Investment LLC has received distributions yielding a 20% internal rate of return as calculated; (ii) second, 100% to the Sponsor as a return of (but not a return on) any additional capital contributions made by the Sponsor on account of manager overruns; and (iii) thereafter, (a) 50% to the members in proportion to their respective percentage interests at the time of such distribution, and (b) fifty percent 50% to the Sponsor.
Subordinated participation interest to CEO (in hundredths)	10.00%			10.00%
Percentage of distribution on company's initial investment to be received prior to CEO receiving percentage distribution (in hundredths)	150.00%
Initial aggregate investment in Investment LLC	57,250,000			57,250,000
Percentage of outstanding shares to be owned by CEO, minimum (in hundredths)	20.00%
Number of purchase agreements	3			3
Area of Real Estate Property	346,000			346,000
Additional capital the Company contributed to Joint Venture for deposit into inclusionary air rights reserve in March 2014	1,086,000			1,086,000
Subsequent Event [Line Items]
Additional capital contributed to Joint Venture in June 2014				5,595,000
Additional capital contributed to Joint Venture in July 2014				5,842,000
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity	867,000			867,000
Equity Method Investment, Summarized Financial Information, Assets [Abstract]
Real estate held for development, net	308,823,000			308,823,000	263,312,000
Escrow deposits	14,930,000			14,930,000	43,100,000
Other assets	21,053,000			21,053,000	18,062,000
Total assets	344,806,000			344,806,000	324,474,000
Equity Method Investment, Summarized Financial Information, Liabilities [Abstract]
Mortgage payable	230,000,000			230,000,000	230,000,000
Other liabilities	5,621,000			5,621,000	2,767,000
Total liabilities	235,621,000			235,621,000	232,767,000
Equity:
Total equity	109,185,000			109,185,000	91,707,000
Total liabilities and equity	344,806,000			344,806,000	324,474,000
Income (Loss) [Abstract]
Rental income	54,000	584,000	599,000	337,000
Expenses	1,061,000	1,059,000	1,094,000	3,621,000
Net income (loss)	$ (1,007,000)	$ (475,000)	$ (495,000)	$ (3,284,000)