Discontinued Operations (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Balance Sheet data (as of the period ended):
Land	$ 198,585	$ 183,060
Buildings, improvements and lease intangibles	3,135,893	3,048,251
Personal property	9,954	9,914
Total real estate properties	3,380,908	3,258,279
Less accumulated depreciation	(761,926)	(700,671)
Assets held for sale, net	2,618,982	2,557,608
Other assets, net (including receivables)	192,918	185,337
Assets held for sale and discontinued operations, net	724	9,146
Liabilities of discontinued operations	33	372
Discontinued Operations [Member]
Balance Sheet data (as of the period ended):
Land	422	422
Buildings, improvements and lease intangibles	1,350	12,822
Personal property	0	13
Total real estate properties	1,772	13,257
Less accumulated depreciation	(1,070)	(4,464)
Assets held for sale, net	702	8,793
Other assets, net (including receivables)	22	353
Assets of discontinued operations, net	22	353
Assets held for sale and discontinued operations, net	724	9,146
Accounts payable and accrued liabilities	28	86
Other liabilities	5	286
Liabilities of discontinued operations	$ 33	$ 372