Selected Quarterly Financial Data (Unaudited) - (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended												12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Rental		$ 29,011	$ 28,835	$ 28,327	$ 27,764	$ 26,877	$ 26,363	$ 26,192	$ 26,192	$ 15,134	$ 0	$ 0	$ 0	$ 113,937	$ 105,624	$ 15,134
Restaurant		4,827	4,676	4,826	4,943	4,391	4,443	4,701	4,859	4,395	4,413	4,624	4,890	19,272	18,394	18,322
Total revenues		33,838	33,511	33,153	32,707	31,268	30,806	30,893	31,051	19,529	4,413	4,624	4,890	133,209	124,018	33,456
Operating Expenses [Abstract]
General and administrative		3,044	2,899	3,459	2,863	2,545	2,608	2,508	3,317	1,856	0	0	0	12,259	10,977	1,856
Depreciation and amortization		5,557	5,425	5,426	5,409	5,230	5,059	5,101	5,187	3,153	208	185	212	21,811	20,577	3,758
Restaurant expenses		4,829	4,571	4,583	4,668	4,254	4,308	4,593	4,698	4,060	4,088	4,335	4,513	18,652	17,853	16,996
Interest expense		5,403	5,463	4,508	4,094	3,239	3,549	3,858	4,182	2,203	0	0	0	19,469	14,828	2,203
Total operating expenses		18,833	18,358	17,976	17,034	15,268	15,524	16,060	17,384	11,272	4,296	4,520	4,725	72,191	64,235	24,813
Other income		113	172	34	5	9	10	18	60					324	97	0
Realized gain on sale, net		3,198	4,042	3,291	0	16,623		0	0					10,532	16,623	0
Income before income taxes		$ 18,316	$ 19,367	$ 18,502	$ 15,678	$ 32,632	$ 15,292	$ 14,851	$ 13,727	$ 8,257	$ 117	$ 104	$ 165	$ 71,874	$ 76,503	$ 8,643
Earnings per share, basic (in USD per share)		$ 0.30	$ 0.31	$ 0.30	$ 0.26	$ 0.54	$ 0.25	$ 0.25	$ 1.95	$ 0.85				$ 1.18	$ 2.75	$ 0.92
Earnings per share, diluted (in USD per share)		0.30	0.31	0.30	0.26	0.54	0.25	0.25	1.61	$ 0.84				1.18	2.63	$ 0.91
Distributions declared per share	$ 0.275	$ 0.2750	$ 0.2425	$ 0.2425	$ 0.2425	$ 0.2425	$ 0.2425	$ 0.2425	$ 0.2425					$ 1.0025	$ 0.970000