Real Estate Properties - Summary of Properties Held for Sale (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2016 USD ($) ft² building property	Dec. 31, 2015 property
Real Estate Properties [Line Items]
Number of Properties		0
Held-for-sale
Real Estate Properties [Line Items]
Number of Properties	4
Number of Buildings | building	4
Square Footage (in sqft) | ft²	1,369,902
Gross Sales Price | $	$ 265,000
Held-for-sale | 111 River Street
Real Estate Properties [Line Items]
Number of Properties	1
Number of Buildings | building	1
Square Footage (in sqft) | ft²	566,215
Gross Sales Price | $	$ 235,000
Held-for-sale | 128 Crews Drive
Real Estate Properties [Line Items]
Number of Properties	1
Number of Buildings | building	1
Square Footage (in sqft) | ft²	185,600
Held-for-sale | 111 Southchase Boulevard
Real Estate Properties [Line Items]
Number of Properties	1
Number of Buildings | building	1
Square Footage (in sqft) | ft²	168,087
Held-for-sale | 1043 Global Avenue
Real Estate Properties [Line Items]
Number of Properties	1
Number of Buildings | building	1
Square Footage (in sqft) | ft²	450,000
Held-for-sale | South Carolina industrial portfolio
Real Estate Properties [Line Items]
Number of Properties	3
Number of Buildings | building	3
Square Footage (in sqft) | ft²	803,687
Gross Sales Price | $	$ 30,000