Preferred Equity Investments - Additional Information (Details) ft² in Thousands		3 Months Ended
	Mar. 01, 2019 USD ($)	Mar. 31, 2019 ft²
Investment Holdings [Line Items]
Preferred equity ownership percentage		24.40%
Area of office properties		12,200
470 Vanderbilt [Member]
Investment Holdings [Line Items]
Area of office properties		686
Preferred Equity Investments, Dividend Rate		10.30%
Preferred equity investments, dividend rate percentage paid		8.00%
Preferred equity investment redeemed | $	$ 36,089,000