Annual report pursuant to Section 13 and 15(d)

Real Estate Activity (Details)

v3.10.0.1
Real Estate Activity (Details)
$ in Thousands
 12 Months Ended
Dec. 31, 2018
USD ($)
a
county
$ / a
Dec. 31, 2017
USD ($)
a
$ / a
Dec. 31, 2016
USD ($)
a
$ / a
Number of Acres      
Land (surface rights) (acre) | a 877,462 877,633  
Real estate acquired (acre) | a 24,715 10,065  
Total real estate situated in 19 counties in Texas (acres) | a 902,177 887,698  
Net Book Value      
Land (surface rights) | $ $ 0 $ 0  
Real estate acquired | $ 10,492 1,115  
Total real estate situated in 19 counties in Texas | $ $ 10,492 $ 1,115  
Number of countries with real estate and land surface rights | county 19    
Area of real estate property, sold (in acres) | a 171.5 11.0 774.6
Proceeds from sale of real estate | $ $ 4,400 $ 200 $ 2,900
Average sales price (in dollars per acre) | $ / a 25,464 20,000 3,803
Additions (acres) | a 14,650    
Additions | $ $ 9,400    
Average purchase price (in dollars per acre) | $ / a 640