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Fair Value Disclosure (Narrative) (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Sep. 30, 2022 | Dec. 31, 2022 | Dec. 31, 2021 | Jun. 30, 2022 | Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Loss (gain) on equity securities |  | $ (283) | $ 3,423 |  |
Long-term debt |  | 18,873 | 20,400 |  |
Quoted prices in active markets for identical assets (level 1) | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Loss (gain) on equity securities |  | 1,900 | 1,700 |  |
Quoted prices in active markets for identical assets (level 1) | Fair Value, Measurements, Recurring | Reported Value Measurement |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Equity securities cost |  |  |  |  | $ 2,000
Quoted prices in active markets for identical assets (level 1) | Fair Value, Measurements, Recurring | Bellaire |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Loss (gain) on equity securities |  | (2,200) | 1,700 |  |
Significant unobservable inputs (level 3) | Fair Value, Nonrecurring |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Carrying amount of long-lived lsset after impairment | $ 0 |  |  |  |
Significant unobservable inputs (level 3) | Fair Value, Nonrecurring | Mineral Management |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Non-cash asset impairment charge | $ 3,900 |  |  |  |
Significant other observable inputs (level 2) |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Long-term debt fair value |  | $ 18,100 | $ 20,500 |  |
Significant other observable inputs (level 2) | Fair Value, Nonrecurring | Mineral Management |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |
Fair value gained from contract termination |  |  |  | $ 4,100 |

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