Commitments and Contingencies (Details Textual) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($) Number	Dec. 31, 2015 USD ($)
Commitments and Contingencies (Textual) [Abstract]
Number of outstanding letters of credit | Number	9
Letter of credit obligation	$ 90,401
Line Of Credit Facility [Line Items]
Outstanding construction financings for leased properties	297,023	$ 258,968
Additional financing to complete construction	637,356
Total contingent purchase obligations	$ 28,713
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	$ 1,056,909
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals	75,296
Capital Leases, Future Minimum Payments Due	$ 97,385
Letter Of Credit Expiration Date Maximum	Dec. 31, 2018
Letter Of Credit Expiration Date Minimum	Jan. 01, 2016