Reporting Segments and Related Information - Reconciliation of Revenues, Segment Profits (Losses) and Net Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues
Segment revenues	$ 45,619	$ 35,255	$ 45,979
Equity in earnings (losses)	3,834	4,227	7,098
Gain on sale of real estate	0	0	1,044
Investment income	1,344	462	457
Other loss	(59)	(275)	(581)
Total revenues and other income	50,738	39,669	53,997
Segment profits (losses) and net income (loss)
Segment profits	436	(7,518)	(6,765)
Costs and expenses	(45,183)	(42,773)	(52,744)
Income (loss) before income taxes	5,555	(3,104)	1,253
Real estate - commercial/industrial
Revenues
Segment revenues	8,970	9,001	9,840
Real estate - resort/residential
Segment profits (losses) and net income (loss)
Costs and expenses	(1,530)	(1,955)	(1,630)
Mineral resources
Revenues
Segment revenues	14,395	5,983	14,153
Ranch operations
Revenues
Segment revenues	3,691	3,837	3,338
Segment profits (losses) and net income (loss)
Costs and expenses	(5,451)	(5,411)	(5,734)
Operating Segments
Revenues
Segment revenues	45,619	35,255	45,979
Segment profits (losses) and net income (loss)
Segment profits	10,141	2,195	5,046
Operating Segments | Real estate - commercial/industrial
Revenues
Segment revenues	8,970	9,001	9,840
Segment profits (losses) and net income (loss)
Segment profits	2,724	2,472	2,740
Costs and expenses	(6,246)	(6,529)	(7,100)
Operating Segments | Real estate - resort/residential
Segment profits (losses) and net income (loss)
Segment profits	(1,530)	(1,955)	(1,630)
Operating Segments | Mineral resources
Revenues
Segment revenues	14,395	5,983	14,153
Segment profits (losses) and net income (loss)
Segment profits	8,172	3,019	6,357
Costs and expenses	(6,223)	(2,964)	(7,796)
Operating Segments | Farming
Revenues
Segment revenues	18,563	16,434	18,648
Segment profits (losses) and net income (loss)
Segment profits	2,535	233	(25)
Costs and expenses	(16,028)	(16,201)	(18,673)
Operating Segments | Ranch operations
Revenues
Segment revenues	3,691	3,837	3,338
Segment profits (losses) and net income (loss)
Segment profits	(1,760)	(1,574)	(2,396)
Corporate
Segment profits (losses) and net income (loss)
Costs and expenses	$ (9,705)	$ (9,713)	$ (11,811)