Preferred Equity Investments - Additional Information (Details)		6 Months Ended
	Mar. 01, 2019 USD ($)	Jun. 30, 2019 ft²
Investment Holdings [Line Items]
Preferred equity ownership percentage		24.40%
Area of office properties		12,200,000
470 Vanderbilt [Member]
Investment Holdings [Line Items]
Area of office properties		686,000
Preferred Equity Investments, Dividend Rate		10.30%
Preferred equity investments, dividend rate percentage paid		8.00%
Preferred equity investment redeemed | $	$ 36,089,000