Note 15 - Derivatives - Fair Value of Derivatives (Details) - Coal Contract [Member] - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Assets Derivatives, gross	$ 160	$ 0
Liabilities, gross	(20,597)	0
Effect of Counterparty Netting	(160)	0
Effect of Counterparty Netting	160	(0)
Assets Derivatives, net	0	0
Liabilities, net	$ (20,437)	$ 0

Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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