Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Revenues	$ 9,294	$ 8,473	$ 27,629	$ 22,821
Operating profit before corporate expenses	2,583	1,389	8,155	4,501
Corporate expenses	(734)	(657)	(2,876)	(2,486)
Corporate expenses	1,849	732	5,279	2,015
Interest expense	738	414	2,215	1,785
Depreciation, depletion and amortization			8,696	9,772
Capital expenditures	8,726	4,710	26,137	11,555
Asset Management [Member]
Segment Reporting Information [Line Items]
Revenues	935	619	2,686	1,919
Operating profit before corporate expenses	392	169	1,103	528
Corporate expenses	(127)	(180)	(496)	(682)
Depreciation, depletion and amortization	219	137	683	408
Capital expenditures	202	100	797	318
Mining Properties [Member]
Segment Reporting Information [Line Items]
Revenues	2,471	2,249	7,779	7,198
Operating profit before corporate expenses	2,083	2,037	6,764	6,531
Corporate expenses	(83)	(69)	(325)	(258)
Depreciation, depletion and amortization	172	38	416	161
Capital expenditures	1	0	11,218	0
Development [Member]
Segment Reporting Information [Line Items]
Revenues	412	401	1,203	1,169
Operating profit before corporate expenses	(865)	(404)	(2,164)	(1,201)
Corporate expenses	(457)	(326)	(1,794)	(1,267)
Depreciation, depletion and amortization	47	53	139	159
Capital expenditures	8,548	4,237	13,927	10,443
Stabilized Joint Venture [Member]
Segment Reporting Information [Line Items]
Revenues	5,476	5,204	15,961	12,535
Operating profit before corporate expenses	973	(413)	2,452	(1,357)
Corporate expenses	(67)	(82)	(261)	(279)
Depreciation, depletion and amortization	2,306	3,568	7,272	8,899
Capital expenditures	(25)	373	195	794
Total Segments [Member]
Segment Reporting Information [Line Items]
Depreciation, depletion and amortization	$ 2,744	$ 3,796	$ 8,510	$ 9,627