Related Party Transactions and Investments in Non-Consolidated Entities (Details 5) $ in Thousands	6 Months Ended
	Jun. 30, 2015 USD ($) entity	Jun. 30, 2014 USD ($) entity	Dec. 31, 2014 USD ($) entity
Related Party Transactions and Investments in Non-Consolidated Entities
Sponsored REITs (in entities) | entity	9	14	10
Balance Sheet Data (unaudited):
Real estate, net	$ 421,429		$ 451,822
Other assets	101,701		127,259
Total liabilities	(198,575)		(203,239)
Shareholders' equity	324,555		$ 375,842
Operating Data (unaudited):
Rental revenues	28,174	$ 23,305
Other revenues	25	14
Operating and maintenance expenses	(15,266)	(11,746)
Depreciation and amortization	(9,925)	(7,677)
Interest expense	(4,930)	(3,431)
Net income (loss)	$ (1,922)	$ 465