Note 15 - Segments of Business - Summary of Reportable Segments Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Revenue	$ 188,334	$ 58,907
Operating Expense	29,233	(8,677)
Depreciation	17,976	9,531
Amount attributable to assets acquired	616,627	357,876	$ 630,554
Capital Expenditures	13,482	9,082
Coal Operations [Member]
Revenue	95,273	58,337
Operating Expense	13,088	(7,446)
Depreciation	13,275	9,496
Amount attributable to assets acquired	391,248	350,076
Capital Expenditures	12,639	9,082
Electric Operations [Member]
Revenue	92,494	0
Operating Expense	18,705	0
Depreciation	4,675	0
Amount attributable to assets acquired	218,132	0
Capital Expenditures	843	0
Corporate and Other [Member]
Revenue	567	570
Operating Expense	(2,560)	(1,231)
Depreciation	26	35
Amount attributable to assets acquired	7,247	7,800
Capital Expenditures	$ 0	$ 0