Note 21 - Derivatives (Details Textual) T in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) T	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Unrealized Gain (Loss) on Derivatives and Commodity Contracts, Total | $	$ (52,204)	$ 0	$ 0
Coal Contract [Member]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts, Total | $	$ 52,204
Coal Contract [Member] | Short [Member]
Derivative, Nonmonetary Notional Amount, Mass (US Ton) | T	2,000
Coal Contract [Member] | Long [Member]
Derivative, Nonmonetary Notional Amount, Mass (US Ton) | T	690