SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION - Change in Total Cost of Real Estate Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]
Balance at the beginning of the year	$ 1,510,864	$ 1,431,374	$ 1,320,273	$ 1,306,192	$ 1,105,504	$ 654,560
Acquisitions	8,171	65,020	133,660	0	187,032	444,233
Dispositions during the year	(17,889)	0	(33,053)	0	0	0
Capital expenditures and transfers from construction-in-progress	19,043	14,470	10,494	14,081	13,656	6,711
Investment in Real Estate	$ 1,520,189	$ 1,510,864	$ 1,431,374	$ 1,320,273	$ 1,306,192	$ 1,105,504