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Represents the coal supply commitment as of the specified date.

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Represents amortized expense for contract with customer asset.

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Represents amortization expense for contract with customer.

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Represents the number of major customers accounting for 10% or more of the specified concentration risk benchmark, which includes, but not limited to, sales revenue, accounts receivable, etc.

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No definition available.

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Represents the number of underground mines that are included in the significant operating segment.

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Represents the quantity of priced coal supply commitment.

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Represents the year in which supply commitments end.

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Amount of allowance for credit loss on accounts receivable.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Value of input used to measure debt instrument, including, but not limited to, convertible and non-convertible debt.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Note 1 - Summary of Significant Accounting Policies (Details Textual) $ in Thousands, T in Millions	5 Months Ended		12 Months Ended		31 Months Ended
	May 31, 2023 USD ($)	May 31, 2022	Dec. 31, 2022 USD ($) T	Dec. 31, 2021 USD ($)	Dec. 31, 2025	Nov. 30, 2023 USD ($)
Number of Reportable Segments			2
Accounts Receivable, Allowance for Credit Loss, Ending Balance			$ 0	$ 0
Regulatory Asset, Total			$ 36,900
Coal Supply Commitment (US Ton) \| T			14.8
Year Supply Commitments End			2027
Priced Coal Supply Commitment (US Ton) \| T			10.8
Revenue, Product and Service Benchmark [Member] \| Customer Concentration Risk [Member] \| Coal [Member]
Number of Major Customers			5	4
Revenue, Product and Service Benchmark [Member] \| Customer Concentration Risk [Member] \| Coal [Member] \| Five Customers [Member]
Concentration Risk, Percentage			90.00%
Revenue, Product and Service Benchmark [Member] \| Customer Concentration Risk [Member] \| Coal [Member] \| Four Customers [Member]
Concentration Risk, Percentage				95.00%
Revenue, Product and Service Benchmark [Member] \| Customer Concentration Risk [Member] \| Electric Distribution [Member]
Number of Major Customers			1
Revenue, Product and Service Benchmark [Member] \| Customer Concentration Risk [Member] \| Electric Distribution [Member] \| One Customer [Member]
Concentration Risk, Percentage			100.00%
Revenue, Product and Service Benchmark [Member] \| Product Concentration Risk [Member] \| Electricity, Generation [Member]
Concentration Risk, Percentage		100.00%
Accounts Receivable [Member] \| Customer Concentration Risk [Member] \| Coal [Member]
Number of Major Customers			4	5
Accounts Receivable [Member] \| Customer Concentration Risk [Member] \| Coal [Member] \| Five Customers [Member]
Concentration Risk, Percentage			86.00%	99.00%
Accounts Receivable [Member] \| Customer Concentration Risk [Member] \| Electric Distribution [Member]
Number of Major Customers			1
Accounts Receivable [Member] \| Customer Concentration Risk [Member] \| Electric Distribution [Member] \| One Customer [Member]
Concentration Risk, Percentage			100.00%
Forecast [Member]
Capacity Payment Reductions	$ 7,500					$ 7,500
Forecast [Member] \| Revenue, Product and Service Benchmark [Member] \| Customer Concentration Risk [Member] \| Energy Output [Member]
Concentration Risk, Percentage	22.00%
Forecast [Member] \| Revenue, Product and Service Benchmark [Member] \| Customer Concentration Risk [Member] \| Energy Capacity [Member]
Concentration Risk, Percentage					32.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)			2 years
Minimum [Member] \| Measurement Input, Discount Rate [Member]
ARO measurement input			0.050
Minimum [Member] \| Surface and Underground Mining Equipment [Member]
Property, Plant and Equipment, Useful Life (Year)			3 years
Minimum [Member] \| Power Plant Equipment [Member]
Property, Plant and Equipment, Useful Life (Year)			4 years
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)			4 years
Maximum [Member] \| Measurement Input, Discount Rate [Member]
ARO measurement input			0.10
Maximum [Member] \| Surface and Underground Mining Equipment [Member]
Property, Plant and Equipment, Useful Life (Year)			25 years
Maximum [Member] \| Power Plant Equipment [Member]
Property, Plant and Equipment, Useful Life (Year)			9 years
Coal Purchase Agreement [Member]
Contract with Customer, Asset, Amortized Expense			$ 14,700
Coal Purchase Agreement [Member] \| Operating Expense [Member]
Contract with Customer, Asset, Amortized Expense			3,600
Power Purchase Agreement [Member]
Contract with Customer, Liability, Amortization Expense			$ 23,300
Southwestern Indiana [Member]
Number of Underground Mines Included in the Significant Operating Segment			2
Sunrise Energy, LLC [Member]
Equity Method Investment, Ownership Percentage			50.00%