Business Segments (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Real estate - commercial/industrial
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	$ 5,547	$ 4,771
Commercial leases
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	3,401	2,958
Grazing leases
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	748	587
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	1,398	578
Mineral resources
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	5,631	7,785
Oil and gas
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	4,418	6,510
Rock aggregate
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	296	305
Cement
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	375	337
Land lease for oil exploration
Revenue components of commercial/industrial real estate segment
Revenue of commercial/industrial real estate segment	$ 542	$ 633