Agreements and Transactions with Related Parties (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Amounts Included in the Consolidated Statements of Income
Asset management fees	$ 29,192	$ 26,694	$ 21,953
Available Cash Distributions	24,668	20,427	16,899
Personnel and overhead reimbursements	12,199	11,931	10,536
Acquisition expenses	430	2,637	11,448
Interest expense on deferred acquisition fees and loan from affiliate	309	516	827
Operating expenses	66,798	62,205	61,663
Acquisition Fees Capitalized
Current acquisition fees	8,180	3,979	4,777
Deferred acquisition fees	6,325	2,510	3,063
Capitalized personnel and overhead reimbursements	858	0	0
Transaction fees incurred	$ 15,363	$ 6,489	$ 7,840