Note 15 - Segment of Business - Summary of Reportable Segments Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Revenue	$ 165,768	$ 85,084	$ 515,296	$ 209,920
Operating Expense	23,803	5,395	75,280	(4,098)
Depreciation	16,230	11,187	51,375	31,882
Amount attributable to assets acquired	585,186	383,361	585,186	383,361	$ 630,554
Capital Expenditures	18,136	15,441	48,746	38,344
Coal Operations [Member]
Revenue	134,896	84,530	343,267	208,190
Operating Expense	24,764	6,098	64,215	580
Depreciation	11,508	11,149	37,249	31,772
Amount attributable to assets acquired	375,682	374,223	375,682	374,223
Capital Expenditures	11,570	15,097	38,654	38,000
Electric Operations [Member]
Revenue	67,544	0	231,141	0
Operating Expense	(2,676)	(991)	25,285	(991)
Depreciation	4,695	0	14,045	0
Amount attributable to assets acquired	209,455	351	209,455	351
Capital Expenditures	6,566	344	10,092	344
Corporate and Other [Member]
Revenue	(36,672)	554	(59,112)	1,730
Operating Expense	1,715	288	(14,220)	(3,687)
Depreciation	27	38	81	110
Amount attributable to assets acquired	49	8,787	49	8,787
Capital Expenditures	$ 0	$ 0	$ 0	$ 0