Real Estate Investments - Discontinued Operations and Assets Held for Sale - Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Balance Sheet data (as of the period ended):
Land	$ 247,772	$ 230,206
Investment Building and Building Improvements	3,845,546	3,675,415
Real estate properties, Total	4,165,765	3,974,071
Accumulated depreciation	(1,064,408)	(1,015,174)
Total real estate properties, net	3,101,357	2,958,897
Liabilities of properties held for sale	511	587
Inpatient Rehabilitation Facility | Disposal Group, Held-for-sale, Not Discontinued Operations
Balance Sheet data (as of the period ended):
Land	2,089	1,125
Investment Building and Building Improvements	36,534	18,231
Real estate properties, Total	38,623	19,356
Accumulated depreciation	(32,594)	(10,657)
Total real estate properties, net	6,029	8,699
Operating lease right-of-use assets	42	0
Other assets, net	544	573
Assets held for sale, net	6,615	9,272
Accounts payable and accrued liabilities	198	450
Operating lease liabilities	42	0
Other liabilities	271	137
Liabilities of properties held for sale	$ 511	$ 587