Commitments and Contingencies - Summary of Properties Under Contracts (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) ft² a property land_parcel
Real Estate Properties [Line Items]
Number of Buildings | property	220
Area of real estate property | a	77.6
Improved land parcels [Member]
Real Estate Properties [Line Items]
Number of Buildings | land_parcel	19
Area of real estate property | ft²	13,300,000
Third-party seller [Member]
Real Estate Properties [Line Items]
Number of Buildings | property	1
Area of real estate property | ft²	65,670
Purchase Price	$ 30,000
Assumed Debt	$ 0
Third-party seller [Member] | Los Angeles [Member]
Real Estate Properties [Line Items]
Number of Buildings | property	1
Area of real estate property | ft²	65,670
Purchase Price	$ 18,000
Assumed Debt	$ 0
Third-party seller [Member] | Northern New Jersey/New York City [Member]
Real Estate Properties [Line Items]
Number of Buildings | property	0
Area of real estate property | ft²	0
Purchase Price	$ 0
Assumed Debt	$ 0
Third-party seller [Member] | Northern New Jersey/New York City [Member] | Improved land parcels [Member]
Real Estate Properties [Line Items]
Number of Buildings | land_parcel	1
Area of real estate property | a	2.78
Third-party seller [Member] | San Francisco Bay Area [Member]
Real Estate Properties [Line Items]
Number of Buildings | property	0
Area of real estate property | ft²	0
Purchase Price	$ 12,000
Assumed Debt	$ 0
Third-party seller [Member] | Seattle [Member]
Real Estate Properties [Line Items]
Number of Buildings | property	0
Area of real estate property | ft²	0
Purchase Price	$ 0
Assumed Debt	$ 0
Third-party seller [Member] | Miami [Member]
Real Estate Properties [Line Items]
Number of Buildings | property	0
Area of real estate property | ft²	0
Purchase Price	$ 0
Assumed Debt	$ 0
Third-party seller [Member] | Washington D.C. [Member]
Real Estate Properties [Line Items]
Number of Buildings | property	0
Area of real estate property | ft²	0
Purchase Price	$ 0
Assumed Debt	$ 0