| Income Taxes - Summary of Temporary Differences in Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands | Dec. 31, 2021 | Dec. 31, 2020 | 
|---|---|---|
| Income Tax Disclosure [Abstract] | ||
| Unearned revenue | $ 5,050 | $ 5,633 | 
| Basis difference in pension plan liability | 128 | 452 | 
| Other | 25 | 0 | 
| Total deferred tax assets | 5,203 | 6,085 | 
| Property, plant and equipment | 16,037 | 16,314 | 
| Real estate and royalty interests | 28,114 | 28,494 | 
| Other | 0 | 5 | 
| Total deferred tax liabilities | 44,151 | 44,813 | 
| Deferred taxes payable | $ (38,948) | $ (38,728) | 
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- Definition Deferred Tax Liability, Real Estate and Royalty Interests No definition available. 
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- Definition Amount of deferred tax liability attributable to taxable temporary differences. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from deferred income. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences, classified as other. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from pension benefits. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef 
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- Definition Amount, after deferred tax asset, of deferred tax liability attributable to taxable differences without jurisdictional netting. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount of deferred tax liability attributable to taxable temporary differences classified as other. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount of deferred tax liability attributable to taxable temporary differences from property, plant, and equipment. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef 
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- References No definition available. 
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