Annual report pursuant to Section 13 and 15(d)

Recent Transactions (Acquisitions) (Narrative) (Details)

v3.8.0.1
Recent Transactions (Acquisitions) (Narrative) (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2017
USD ($)
property
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Real Estate Properties [Line Items]      
Purchase price of property $ 90,068 $ 121,582 $ 94,073
Jersey City, Morris Township And Red Bank, New Jersey [Member]      
Real Estate Properties [Line Items]      
Number of real estate properties | property 3    
Purchase price of property $ 80,000