Agreements and Transactions with Related Parties (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Amounts included in the statement of income:
Asset management fees	$ 18,932	$ 13,435	$ 5,050
Distributions of available cash	14,620	9,378	4,468
Personnel reimbursements	5,205	2,258	915
Office rent reimbursements	756	411	165
Operating Expenses	39,513	25,482	10,598
Transaction fees incurred:
Current acquisition fees	24,463	24,559	24,808
Deferred acquisition fees	19,240	17,398	19,101
Transaction Fees Incurred	43,703	41,957	43,909
Unpaid transaction fees:
Deferred acquisition fees	26,246	22,748
Subordinated disposition fees	202	202
Unpaid Transaction Fees	$ 26,448	$ 22,950