Held for Sale and Discontinued Operations (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Balance Sheet data (as of the period ended):
Land	$ 199,672	$ 198,585
Buildings, improvements and lease intangibles	3,386,480	3,135,893
Total real estate properties	3,628,221	3,380,908
Less accumulated depreciation	(840,839)	(761,926)
Total real estate properties, net	2,787,382	2,618,982
Other assets, net (including receivables)	195,666	186,416
Assets held for sale and discontinued operations, net	3,092	724
Liabilities of assets held for sale and discontinued operations	614	33
Discontinued Operations [Member]
Balance Sheet data (as of the period ended):
Land	1,362	422
Buildings, improvements and lease intangibles	4,410	1,350
Total real estate properties	5,772	1,772
Less accumulated depreciation	(2,977)	(1,070)
Total real estate properties, net	2,795	702
Other assets, net (including receivables)	297	22
Assets of discontinued operations, net	297	22
Assets held for sale and discontinued operations, net	3,092	724
Accounts payable and accrued liabilities	22	28
Other liabilities	592	5
Liabilities of assets held for sale and discontinued operations	$ 614	$ 33