Organization (Details) ft² in Millions	3 Months Ended
	Mar. 31, 2016 ft² property
Concentration Risk [Line Items]
Number of properties owned | property	19
Area of real estate properties | ft²	3.3
Occupancy percentage	95.10%
Weighted-average remaining lease term	9 years 3 months 18 days
Office Building [Member] | Property Type Concentration Risk [Member] | Composition of Real Estate Portfolio [Member]
Concentration Risk [Line Items]
Concentration risk percent	83.00%
Retail Site [Member] | Property Type Concentration Risk [Member] | Composition of Real Estate Portfolio [Member]
Concentration Risk [Line Items]
Concentration risk percent	9.00%
Other Property [Member] | Property Type Concentration Risk [Member] | Composition of Real Estate Portfolio [Member]
Concentration Risk [Line Items]
Concentration risk percent	8.00%