Note 3 - Inventory	12 Months Ended
Dec. 31, 2020
Notes to Financial Statements
Inventory Disclosure [Text Block]	(3) INVENTORY Inventory is valued at lower of average cost or net realizable value (NRV). As of December 31, 2020, and December 31, 2019, coal inventory includes NRV adjustments of $1.6 million and $2.0 million, respectively.

The entire disclosure for inventory. Includes, but is not limited to, the basis of stating inventory, the method of determining inventory cost, the classes of inventory, and the nature of the cost elements included in inventory.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-URI http://asc.fasb.org/topic&trid=2126998

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