Note 7 - Revenue 1 (Details Textual)	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2024 USD ($) MWh	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)	Jan. 01, 2023 USD ($)
Contract Capacity [Member]
Contract with Customer, Liability	$ 39,800,000	$ 39,800,000
Additional Obligations [Member]
Contract with Customer, Liability	45,000,000	45,000,000
Coal [Member]
Accounts Receivable, after Allowance for Credit Loss				$ 16,300,000
Hoosier [Member]
Long Term Purchase Agreement, Prepaid Contract Amount	$ 45,000,000
Long Term Purchase Commitment, Total Usage of Power, Megawatt Per Hour (Megawatt-Hour) | MWh	1,302,480
Hoosier [Member] | Contract Capacity [Member]
Long-term Purchase Commitment, Minimum Quantity Required, Price Per Megawatt Hour		56
Revenue, Remaining Performance Obligation, Amount	$ 186,600,000	186,600,000
Long-term Purchase Commitment, Stand Ready Obligation, Contract Capacity, Price Per Kilowatts-month		$ 7.02
Hoosier [Member] | Electricity, Purchased [Member]
Long-term Purchase Commitment, Minimum Quantity Required, Price Per Megawatt Hour			$ 34
Long-term Purchase Commitment, Stand Ready Obligation, Contract Capacity, Megawatts Provided Year One		917
Long-term Purchase Commitment, Stand Ready Obligation, Contract Capacity, Megawatts Provided Year Two Through Four		300
Long-term Purchase Commitment, Stand Ready Obligation, Contract Capacity, Price Per Kilowatts-month		$ 5.8