Note 7 - Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Net operating loss	$ 20,029	$ 26,570
Power contracts	23,302	34,233
Compensation	2,287	1,344
Accrued liabilities	570	556
Other	2,016	471
Total deferred tax assets	48,204	63,174
Valuation allowance		(3,681)
Deferred tax assets, net of valuation allowance	48,204	59,493
Coal properties	(25,764)	(27,700)
Power properties	(31,126)	(35,702)
Investment partnerships	(549)	(494)
Other		(203)
Total deferred tax liabilities	(57,439)	(64,099)
Net deferred tax liability	$ (9,235)	$ (4,606)