Agreements and Transactions with Related Parties (Details 1) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Amounts Included in the Consolidated Statements of Income
Asset management fees	$ 7,300	$ 6,846	$ 14,442	$ 13,465
Available Cash Distributions	5,789	4,590	11,853	9,269
Personnel and overhead reimbursements	2,696	2,824	6,152	6,324
Interest expense on deferred acquisition fees and loan from affiliate	60	129	133	280
Acquisition expenses	0	298	430	1,191
Operating expenses	15,845	14,687	33,010	30,529
Acquisition Fees Capitalized
Current acquisition fees	2,504	1,351	4,938	1,355
Deferred acquisition fees	2,003	682	3,732	690
Transaction fees incurred	$ 4,507	$ 2,033	$ 8,670	$ 2,045