Business Segments - Business segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015	Sep. 30, 2015
Segment Reporting Information [Line Items]
Revenues	$ 9,615	$ 8,948	$ 18,438	$ 17,250
Operating profit	3,509	2,159	10,109	4,504
Corporate expenses unallocated to discontinued operations	0	(162)	0	(1,081)
Interest expense	415	620	896	1,065
Depreciation, depletion and amortization			3,957	3,851
Cash items	1,175		1,175		$ 419
Total identifiable net assets	256,142		256,142		252,478
Asset Management
Segment Reporting Information [Line Items]
Revenues	7,574	7,330	14,489	14,087
Operating profit before corporate expenses	3,423	3,187	6,811	6,573
Allocated corporate expenses	(520)	(497)	(898)	(797)
Interest expense	415	620	896	1,065
Capital expenditures	473	382	9,710	1,287
Depreciation, depletion and amortization	1,835	1,776	3,633	3,562
Total identifiable net assets	157,566		157,566		151,023
Mining royalty lands
Segment Reporting Information [Line Items]
Revenues	1,778	1,335	3,437	2,679
Operating profit before corporate expenses	1,649	1,191	3,174	2,391
Allocated corporate expenses	(75)	(526)	(130)	(844)
Capital expenditures	4	0	4	0
Depreciation, depletion and amortization	31	30	65	61
Total identifiable net assets	39,479		39,479		39,300
Land Development and Construction
Segment Reporting Information [Line Items]
Revenues	263	283	512	484
Operating profit before corporate expenses	(555)	(739)	1,864	(1,267)
Allocated corporate expenses	(413)	(295)	(712)	(471)
Capital expenditures	479	309	1,781	1,142
Depreciation, depletion and amortization	63	72	127	138
Total identifiable net assets	57,365		57,365		60,682
Corporate
Segment Reporting Information [Line Items]
Total identifiable net assets	557		557		$ 1,054
Total Segments
Segment Reporting Information [Line Items]
Revenues	9,615	8,948	18,438	17,250
Operating profit	3,509	2,159	10,109	4,504
Allocated corporate expenses	(1,008)	(1,480)	(1,740)	(3,193)
Corporate expenses unallocated to discontinued operations	0	(162)	0	(1,081)
Interest expense	415	620	896	1,065
Capital expenditures	956	691	11,495	2,429
Depreciation, depletion and amortization	$ 1,929	$ 1,878	$ 3,825	$ 3,761