Note 19 - Commitments and Contingencies (Details Textual) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Sep. 29, 2023	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Revenue from Contract with Customer, Excluding Assessed Tax		$ 105,251	$ 90,696	$ 242,058	$ 210,384
Unrecorded Unconditional Purchase Obligation		150,000		150,000
Policyholder Benefits and Claims Incurred, Direct		300	600	900	1,700
Restricted Cash, Current		25,267		25,267		$ 26,608
BP Energy Company, Preferred Supplier Agreement [Member]
Accounts Payable, Trade		24,200		24,200
BP Energy Company, Preferred Supplier Agreement [Member] | Asset Pledged as Collateral [Member]
Restricted Cash, Current		1,400		1,400
Accounts Receivable, after Allowance for Credit Loss		67,000		67,000
Surety Bond [Member]
Guarantor Obligations, Current Carrying Value		27,500		27,500
Financial Standby Letter of Credit [Member] | Unused lines of Credit [Member]
Guarantor Obligations, Current Carrying Value		1,000		1,000
Insurance Premium [Member]
Restricted Cash and Cash Equivalent		39,600		39,600
Restricted Cash and Cash Equivalent, Current		16,800		16,800		18,800
Restricted Cash and Cash Equivalent, Noncurrent		70,300		70,300		$ 69,600
Electricity [Member]
Unrecorded Unconditional Purchase Obligation		140,000		140,000
Unrecorded Unconditional Purchase Obligation, Purchases		30,100	19,900	59,800	44,500
Renewable Energy Credits [Member]
Unrecorded Unconditional Purchase Obligation		10,000		10,000
Unrecorded Unconditional Purchase Obligation, Purchases		4,200	8,100	4,700	9,900
Violations of Illinois Consumer Fraud and Deceptive Business Practices Act [Member] | Loss from Alleged Violations [Member] | Residents Energy [Member]
Loss Contingency, Damages Sought, Value Per Violation	$ 50
Revenue from Contract with Customer, Excluding Assessed Tax		$ 5,500	$ 8,200	$ 13,600	$ 20,700