Note 3 - Property, Plant and Equipment (Details) $ in Millions	1 Months Ended
Dec. 31, 2021 USD ($)
Coronado Global Resources Inc.
Asset Acquisition [Line Items]
Amount of cash consideration	$ 30

Amount of contingent consideration recognized as part of consideration transferred in asset acquisition.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 50
-Section 30
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=126928898&loc=d3e9212-128498

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 50
-Section 25
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=127000608&loc=d3e9135-128495

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 50
-Section 30
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=126928898&loc=d3e9215-128498

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration