Real Estate Investments - Discontinued Operations and Assets Held for Sale - Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Balance Sheet data (as of the period ended):
Land	$ 193,101	$ 199,672
Buildings, improvements and lease intangibles	3,327,529	3,386,480
Real estate properties, Total	3,566,865	3,628,221
Accumulated depreciation	(841,296)	(840,839)
Total real estate properties, net	2,725,569	2,787,382
Other assets, net (including receivables)	192,174	195,666
Assets held for sale and discontinued operations, net	15,111	3,092
Liabilities of discontinued operations	93	614
Discontinued Operations
Balance Sheet data (as of the period ended):
Land	1,915	1,362
Buildings, improvements and lease intangibles	28,991	4,410
Real estate properties, Total	30,906	5,772
Accumulated depreciation	(16,721)	(2,977)
Total real estate properties, net	14,185	2,795
Other assets, net (including receivables)	926	297
Assets held for sale and discontinued operations, net	15,111	3,092
Accounts payable and accrued liabilities	93	22
Other liabilities	0	592
Liabilities of discontinued operations	$ 93	$ 614