Business Segments - Schedule of Operating Results and Certain Other Financial Data for Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Segment Reporting Information [Line Items]
Revenues	$ 10,775	$ 10,633	$ 31,931	$ 31,243
Operating profit (loss)	3,691	5,372	13,135	15,668
General and administrative expenses	2,328	2,289	7,790	6,883
Total operating profit	1,363	3,083	5,345	8,785
Interest expense	739	742	2,258	2,482
Depreciation, depletion and amortization			8,627	7,840
Capital expenditures	24,993	34,571	34,154	47,089
Operating Segments
Segment Reporting Information [Line Items]
Depreciation, depletion and amortization	2,825	2,551	8,158	7,629
Operating Segments | Industrial and commercial
Segment Reporting Information [Line Items]
Revenues	1,229	1,455	3,950	4,353
Operating profit (loss)	341	842	1,427	2,484
Depreciation, depletion and amortization	567	360	1,529	1,083
Capital expenditures	129	235	267	628
Operating Segments | Mining royalty lands
Segment Reporting Information [Line Items]
Revenues	3,689	3,199	10,532	9,393
Operating profit (loss)	3,384	2,946	9,689	8,655
Depreciation, depletion and amortization	213	163	568	471
Capital expenditures	297	18	525	60
Operating Segments | Development
Segment Reporting Information [Line Items]
Revenues	301	297	902	905
Operating profit (loss)	(1,189)	25	(1,802)	102
Depreciation, depletion and amortization	43	43	129	128
Capital expenditures	24,523	34,265	32,697	46,146
Operating Segments | Multifamily
Segment Reporting Information [Line Items]
Revenues	5,556	5,682	16,547	16,592
Operating profit (loss)	1,155	1,559	3,821	4,427
Depreciation, depletion and amortization	2,002	1,985	5,932	5,947
Capital expenditures	$ 44	$ 53	$ 665	$ 255