Schedule III - Real Estate Assets and Accumulated Depreciation - Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Real estate:
Balance at the beginning of the period	$ 1,605,081	$ 1,368,157	$ 1,266,484
Acquisitions	84,630	318,070	106,208
Improvements	7,223	3,103	7,230
Impairment	0	(21,465)	0
Sales of real estate	(13,729)	(62,784)	(11,765)
Balance at the end of the period	1,683,205	1,605,081	1,368,157
Accumulated depreciation:
Balance at the beginning of the period	(220,359)	(185,926)	(152,185)
Depreciation expense	(41,914)	(40,373)	(34,676)
Impairment	0	5,220	0
Sales of real estate	2,470	720	935
Balance at the end of the period	$ (259,803)	$ (220,359)	$ (185,926)