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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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Amount, excluding unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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