Business Segments (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Real estate - commercial/industrial
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	$ 8,389	$ 7,509
Commercial leases
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	5,078	4,537
Grazing leases
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	1,090	958
Land Sale
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	0	648
All other land management ancillary services
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	2,221	1,366
Mineral resources
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	8,055	11,232
Oil and gas
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	6,198	9,137
Rock aggregate
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	639	944
Cement
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	581	559
Land lease for oil exploration
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	$ 637	$ 592