Concentration of Credit Risk (Details)	Dec. 31, 2020 ft² a property	Dec. 19, 2019 ft² building
Real Estate Properties [Line Items]
Number of properties	222	17
Area of real estate property | ft²		699,104
Northern New Jersey/New York City
Real Estate Properties [Line Items]
Percentage accounted by properties of its annualized base rent	29.50%
Northern New Jersey/New York City | Office building
Real Estate Properties [Line Items]
Number of properties | property	62
Area of real estate property | ft²	3,600,000
Northern New Jersey/New York City | Land parcels
Real Estate Properties [Line Items]
Number of properties | property	9
Area of real estate property | a	48.6