Real Estate Investments Business Acquisitions (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Business Acquisition [Line Items]
Payments for Deposits on Real Estate Acquisitions	$ 1,300,000
Purchase Price	35,294,000	$ 0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	10,171,000
Intangible Liabilities	$ 2,940,000
Garden City [Member]
Business Acquisition [Line Items]
Date Purchased	Feb. 22, 2016
Property Name	Garden City Park
City/State	Garden City Park, NY
Business Acquisition, Description of Acquired Entity	Operating
Ownership	100.00%
Purchase Price	$ 17,300,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	10,171,000
Intangible Liabilities	$ 2,940,000
The Market at Springwoods Village [Member]
Business Acquisition [Line Items]
Date Purchased	Mar. 04, 2016
Property Name	The Market at Springwoods Village (1)
City/State	Houston, TX
Business Acquisition, Description of Acquired Entity	Development
Ownership	53.00%
Purchase Price	$ 17,994,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	0
Non-controlling interest recorded, fair value	8,400,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	0
Intangible Liabilities	0
Partnership Interest [Member]
Business Acquisition [Line Items]
Contributions from limited partners in consolidated partnerships, net	8,362,000	13,000
Payments for Deposits on Real Estate Acquisitions	0	4,000,000
Non-controlling interest recorded, fair value	$ 0	$ 0