Commitments and Contingencies (Details Textual) (USD $)	3 Months Ended
	Mar. 31, 2014 Number	Dec. 31, 2013
Commitments and Contingencies (Textual) [Abstract]
Number of outstanding letters of credit	5
Letter of credit obligation	$ 5,301,000
Outstanding construction financings for leased properties	144,516,000	141,085,000
Additional financing to complete construction	224,139,000
Total contingent purchase obligations	66,640,000
Minimum part of economic life of the leased asset to be classified as capital lease	75.00%
Minimum net present value of the future minimum lease payments to be classified as capital lease.	90.00%
Operating lease obligations relating to certain ground leases	878,401,000
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals	43,214,000
Capital Leases, Future Minimum Payments Due	$ 115,770,000