Investments in Real Estate Entities - Financial Position and Operating Results (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Assets:
Real estate, net	$ 689,612		$ 695,077
Other assets	38,084		39,976
Total assets	727,696		735,053
Liabilities and partners' capital:
Mortgage notes payable and credit facility	523,008		523,815
Other liabilities	13,406		10,540
Partners' capital	191,282		200,698
Total liabilities and partners' capital	727,696		$ 735,053
Combined summary of the operating results of the accounted for using the equity method
Rental and other income	21,801	$ 28,642
Operating and other expenses	(8,305)	(11,094)
Gain on sale of communities	0	29,447
Interest expense, net	(5,618)	(6,948)
Depreciation expense	(5,880)	(7,327)
Net income	$ 1,998	$ 32,720