Business Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Real estate - commercial/industrial
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	$ 2,722	$ 2,148
Commercial leases
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	1,659	1,416
Grazing leases
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	374	293
Land Sale
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	0	141
All other land management ancillary services
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	689	298
Mineral resources [Member]
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	2,866	3,906
Oil and Gas
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	2,254	3,331
Rock Aggregate
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	140	112
Cement
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	160	149
Land Lease for Oil Exploration
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	$ 312	$ 314