Real Estate Investments - Discontinued Operations and Assets Held for Sale - Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Balance Sheet data (as of the period ended):
Land	$ 267,803	$ 230,206
Buildings, improvements and lease intangibles	3,915,308	3,675,415
Real estate properties, Total	4,262,698	3,974,071
Accumulated depreciation	(1,106,387)	(1,015,174)
Total real estate properties, net	3,156,311	2,958,897
Liabilities of properties held for sale	300	587
Inpatient Rehabilitation Facility | Disposal Group, Held-for-sale, Not Discontinued Operations
Balance Sheet data (as of the period ended):
Land	1,125	1,125
Buildings, improvements and lease intangibles	34,426	18,231
Real estate properties, Total	35,551	19,356
Accumulated depreciation	(30,706)	(10,657)
Total real estate properties, net	4,845	8,699
Other assets, net	444	573
Assets held for sale, net	5,289	9,272
Accounts payable and accrued liabilities	93	450
Other liabilities	207	137
Liabilities of properties held for sale	$ 300	$ 587