Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Minimum Future Rental Receipts [Abstract]
2016	$ 347,551
2017	328,659
2018	310,051
2019	282,296
2020	249,528
Thereafter	6,654,870
Future Minimum Payments Receivable	8,172,955
Leaseholds Interests [Member]
Future Rental Payments [Abstract]
2016	5,032
2017	4,987
2018	4,819
2019	4,313
2020	4,306
Thereafter	34,346
Future Minimum Payments Due	57,803
Rent expense for leasehold interests	868	$ 919	$ 1,284
Corporate HQ and Office Space [Member]
Future Rental Payments [Abstract]
2016	467
2017	1,243
2018	1,224
2019	1,224
2020	1,224
Thereafter	6,795
Rent expense for leasehold interests	$ 1,435	$ 1,356	$ 1,338