Investments in Unconsolidated Real Estate Joint Ventures (Joint Venture Fees) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Management, Leasing and Marketing Fees [Line Items]
Fees received	$ 1,283	$ 566
Development and Leasing Fee [Member]
Management, Leasing and Marketing Fees [Line Items]
Fees received	581	8
Loan Guarantee Fee [Member]
Management, Leasing and Marketing Fees [Line Items]
Fees received	196	40
Management and Marketing Fee [Member]
Management, Leasing and Marketing Fees [Line Items]
Fees received	$ 506	$ 518