Schedule III - Real Estate and Accumulated Depreciation - Changes in Real Estate Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION
Beginning balance	$ 790,696	$ 759,703	$ 715,300
Purchase of real estate investments	5,981	41,230	47,279
Sale and disposal of real estate investment	(4,422)	(10,222)	(1,267)
Provision for asset impairment	0	0	0
Construction in progress not yet placed in service	9,773	(15)	(1,609)
Ending balance	$ 802,028	$ 790,696	$ 759,703