Investments in Unconsolidated Real Estate Joint Ventures (Joint Venture Fees) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Management, Leasing and Marketing Fees [Line Items]
Fees received	$ 588	$ 806	$ 1,776	$ 3,259
Management and Marketing Fee [Member]
Management, Leasing and Marketing Fees [Line Items]
Fees received	564	656	1,676	2,199
Development and Leasing Fee [Member]
Management, Leasing and Marketing Fees [Line Items]
Fees received	20	65	87	611
Loan Guarantee Fee [Member]
Management, Leasing and Marketing Fees [Line Items]
Fees received	$ 4	$ 85	$ 13	$ 449