Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Minimum Future Rental Receipts [Abstract]
2018	$ 354,240
2019	333,463
2020	304,651
2021	284,114
2022	265,346
Thereafter	2,114,450
Future Minimum Payments Receivable	3,656,264
Leaseholds Interests [Member]
Future Rental Payments [Abstract]
2018	4,330
2019	3,887
2020	3,886
2021	3,829
2022	3,893
Thereafter	28,727
Future Minimum Payments Due	48,552
Rent expense for leasehold interests	690	$ 987	$ 868
Corporate HQ and Office Space [Member]
Future Rental Payments [Abstract]
2018	1,298
2019	1,294
2020	1,297
2021	1,325
2022	1,336
Thereafter	4,238
Rent expense for leasehold interests	1,256	1,242	1,435
LCIF [Member]
Minimum Future Rental Receipts [Abstract]
2018	73,224
2019	68,794
2020	63,719
2021	59,332
2022	54,811
Thereafter	534,397
Future Minimum Payments Receivable	854,277
Future Rental Payments [Abstract]
Rent expense for leasehold interests	$ 171	$ 286	$ 307