Preferred Equity Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Investment Holdings [Line Items]
Preferred equity ownership percentage	24.40%
Preferred equity investments	$ 55,051	$ 53,941
470 Vanderbilt Avenue [Member]
Investment Holdings [Line Items]
Preferred equity ownership percentage	24.40%
Preferred Equity Investments, Dividend Rate	10.30%
Preferred Equity Investments, Initial Maturity	2019-02
Preferred equity investments	$ 35,613	35,305
2 Herald Square [Member]
Investment Holdings [Line Items]
Preferred equity ownership percentage	24.40%
Preferred Equity Investments, Dividend Rate	10.30%
Preferred Equity Investments, Initial Maturity	2017-04
Preferred equity investments	$ 19,438	$ 18,636