Schedule III - Real Estate Assets and Accumulated Depreciation - Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Real estate:
Balance at the beginning of the period	$ 1,368,157	$ 1,266,484	$ 986,215
Acquisitions	318,070	106,208	280,477
Improvements	3,103	7,230	744
Impairment	(21,465)	0	0
Sales of real estate	(62,784)	(11,765)	(952)
Balance at the end of the period	1,605,081	1,368,157	1,266,484
Accumulated depreciation:
Balance at the beginning of the period	(185,926)	(152,185)	(121,797)
Depreciation expense	(40,373)	(34,676)	(30,493)
Impairment	5,220	0	0
Sales of real estate	720	935	105
Balance at the end of the period	$ (220,359)	$ (185,926)	$ (152,185)