Annual report pursuant to Section 13 and 15(d)

Organization and Description of Business Segments (Details)

v3.20.4
Organization and Description of Business Segments (Details)
a in Thousands
12 Months Ended
Dec. 31, 2020
a
segment
Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Line Items]    
Number of operating segments | segment 2  
1/16th nonparticipating perpetual royalty interest    
Organization, Consolidation and Presentation of Financial Statements [Line Items]    
Nonparticipating perpetual royalty interest rate (in percentage) 6.25% 6.25%
1/128th nonparticipating perpetual royalty interest    
Organization, Consolidation and Presentation of Financial Statements [Line Items]    
Nonparticipating perpetual royalty interest rate (in percentage) 0.78125% 0.78125%
West Texas    
Organization, Consolidation and Presentation of Financial Statements [Line Items]    
Area of land (in acres) 880  
West Texas | 1/128th Nonparticipating perpetual oil and gas royalty interest    
Organization, Consolidation and Presentation of Financial Statements [Line Items]    
Area of land (in acres) 85  
West Texas | 1/16th Nonparticipating perpetual oil and gas royalty interest    
Organization, Consolidation and Presentation of Financial Statements [Line Items]    
Area of land (in acres) 371  
West Texas | 1/8th Net royalty acres    
Organization, Consolidation and Presentation of Financial Statements [Line Items]    
Area of land (in acres) 4