Investment in Unconsolidated Joint Venture (Details) - USD ($) $ in Thousands		12 Months Ended
	Dec. 15, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	May 08, 2017
Schedule of Equity Method Investments [Line Items]
Mezzanine financing to unaffiliated third party Entity		$ 15,300
Amount of senior construction loan taken by unconsolidated joint venture		40,000
Outstanding principal balance under mezzanine Loan		15,300
Escrow Deposits Related to Property Sales		$ 0	$ 0	$ 912
Mezzanine loan [Member]
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					11.00%
Senior Lender's loan [Member]
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Description of Variable Rate Basis		increased the interest rate by 75 basis points to 30-day LIBOR plus 3.75%
Prospect Park
Schedule of Equity Method Investments [Line Items]
Real Estate Property Contractual Sales Price				100,500
Proceeds from Sale of Real Estate	$ 21,600
Escrow Deposits Related to Property Sales	$ 15,100
Equity Method Investments			14,700	10,900
Equity Earnings Related to Unconsolidated Investment		$ 17,900
Minimum
Schedule of Equity Method Investments [Line Items]
Annual interest rate for mezzanine loan		10.00%
Minimum | Prospect Park
Schedule of Equity Method Investments [Line Items]
Interest Costs Capitalized			$ 200
Maximum
Schedule of Equity Method Investments [Line Items]
Annual interest rate for mezzanine loan		18.00%
Maximum | Prospect Park
Schedule of Equity Method Investments [Line Items]
Interest Costs Capitalized				$ 500