Investments in Unconsolidated Real Estate Joint Ventures (Joint Venture Fees) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Management, Leasing and Marketing Fees [Line Items]
Fees received	$ 579	$ 1,121
Management and Marketing Fee [Member]
Management, Leasing and Marketing Fees [Line Items]
Fees received	542	747
Development and Leasing Fee [Member]
Management, Leasing and Marketing Fees [Line Items]
Fees received	32	192
Loan Guarantee Fee [Member]
Management, Leasing and Marketing Fees [Line Items]
Fees received	$ 5	$ 182