Held for Sale (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Balance Sheet data (as of the period ended):
Land	$ 230,206	$ 201,283
Buildings, improvements and lease intangibles	3,675,415	3,601,460
Personal property	10,696	10,314
Total real estate properties	3,974,071	3,838,638
Less accumulated depreciation	(1,015,174)	(897,430)
Total real estate properties, net	2,958,897	2,941,208
Other assets, net	214,697	213,015
Assets held for sale, net	9,272	33,147
Liabilities of properties held for sale	587	93
Discontinued Operations [Member]
Balance Sheet data (as of the period ended):
Land	1,125	4,636
Buildings, improvements and lease intangibles	18,231	63,654
Personal property	0	82
Total real estate properties	19,356	68,372
Less accumulated depreciation	(10,657)	(35,790)
Total real estate properties, net	8,699	32,582
Other assets, net	573	565
Assets held for sale, net	9,272	33,147
Accounts payable and accrued liabilities	450	38
Other liabilities	137	55
Liabilities of properties held for sale	$ 587	$ 93