Real Estate Investments - Discontinued Operations and Assets Held for Sale - Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Balance Sheet data (as of the period ended):
Land	$ 193,072	$ 199,672
Buildings, improvements and lease intangibles	3,388,734	3,386,480
Real estate properties, Total	3,612,084	3,628,221
Accumulated depreciation	(864,573)	(840,839)
Total real estate properties, net	2,747,511	2,787,382
Other assets, net (including receivables)	191,036	195,666
Assets held for sale and discontinued operations, net	8,767	3,092
Liabilities of discontinued operations	398	614
Discontinued Operations
Balance Sheet data (as of the period ended):
Land	1,125	1,362
Buildings, improvements and lease intangibles	18,231	4,410
Real estate properties, Total	19,356	5,772
Accumulated depreciation	(10,657)	(2,977)
Total real estate properties, net	8,699	2,795
Other assets, net (including receivables)	68	297
Assets held for sale and discontinued operations, net	8,767	3,092
Accounts payable and accrued liabilities	186	22
Other liabilities	213	592
Liabilities of discontinued operations	$ 399	$ 614