Investments in Unconsolidated Real Estate Joint Ventures (Joint Venture Fees) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Management, Leasing and other services [Line Items]
Fees received	$ 613	$ 579
Management and Marketing Fee [Member]
Management, Leasing and other services [Line Items]
Fees received	567	542
Leasing and other fees [Member]
Management, Leasing and other services [Line Items]
Fees received	$ 46	$ 37