Quarterly report pursuant to Section 13 or 15(d)

Condensed Consolidated Balance Sheets (Parenthetical)

v3.8.0.1
Condensed Consolidated Balance Sheets (Parenthetical)
$ in Thousands
 3 Months Ended
Mar. 31, 2018
USD ($)
a
county
$ / shares
shares
Dec. 31, 2017
USD ($)
a
$ / shares
shares
Property, plant and equipment, net of accumulated depreciation of $791 and $463 as of March 31, 2018 and December 31, 2017, respectively | $ $ 791 $ 463
Number of counties with land surface rights | county 18  
Certificates of proprietary interest, par value (in dollars per share) | $ / shares $ 100 $ 100
Certificates of proprietary interest, outstanding (in shares) | shares 0 0
Sub-share certificates of proprietary interest, par value (in dollars per share) | $ / shares $ 0.0333 $ 0.0333
Sub-share certificates of proprietary interest, outstanding (in shares) | shares 7,808,453 7,821,599
Land Surface Rights    
Land (surface rights), acres (Acre) 877,514 877,633
1/16th Nonparticipating Perpetual Royalty Interest    
Nonparticipating perpetual royalty interest in acres (Acre) 373,777 373,777
1/128th Nonparticipating Perpetual Royalty Interest    
Nonparticipating perpetual royalty interest in acres (Acre) 85,414 85,414