Investment in 111 West 57th Partners LLC (Details) (USD $)	0 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2014 sqft Agreement	Jun. 30, 2014 sqft Agreement	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		288,486,000	288,486,000	263,312,000
Escrow deposits		31,322,000	31,322,000	43,100,000
Other assets		15,975,000	15,975,000	18,062,000
Total assets		335,783,000	335,783,000	324,474,000
Equity Method Investment, Summarized Financial Information, Liabilities [Abstract]
Mortgage payable		230,000,000	230,000,000	230,000,000
Other liabilities		5,276,000	5,276,000	2,767,000
Total liabilities		235,276,000	235,276,000	232,767,000
Equity:
Total equity		100,507,000	100,507,000	91,707,000
Total liabilities and equity		335,783,000	335,783,000	324,474,000
Income (Loss) [Abstract]
Rental income	15,000	10,000	283,000
Expenses	35,000	1,290,000	2,560,000
Net income (loss)	$ (20,000)	$ (1,280,000)	$ (2,277,000)