Schedule III - Real Estate and Accumulated Depreciation - Summarized Activity for Real Estate and Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Balance at beginning of period	$ 1,070,606	$ 881,251	$ 770,779
Acquisition of real estate		166,630	92,310
Additions during period	45,642	22,725	18,162
Write-off of assets as a result of involuntary conversion	(49)
Balance at end of period	1,116,199	1,070,606	881,251
Balance at beginning of period	73,714	58,174	44,672
Depreciation expense	16,765	15,540	13,502
Write-off of assets as a result of involuntary conversion	(17)
Balance at end of period	$ 90,462	$ 73,714	$ 58,174