Note 4 - Acquisitions (Details) a in Thousands, $ in Thousands, MT in Millions			1 Months Ended	12 Months Ended
	Sep. 23, 2022 USD ($) a	Apr. 29, 2022 USD ($) a	Dec. 31, 2021 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($) MT
Asset Acquisition
Fair value of assets				$ 459,091	$ 429,842
Payment of cash bond replacement obligation				1,200
Maben Coal LLC
Asset Acquisition
Voting interest acquired	100.00%
Ramaco Coal Asset Acquisition
Asset Acquisition
Purchase price		$ 65,000
Initial payment		10,000
Deferred purchase price payable due in remainder of 2022		55,000
Quarterly Installment amount in remainder of 2022		5,000
Quarterly Installment amount in remainder of 2023		$ 10,000
Interest rate (as a percent)		9.00%
Area of thermo coal deposit Wyoming | a		16
Upfront payment receivable on royalty		$ 2,000
Minimum quarterly royalty payment receivable		125
Fair value of acquisition		3,700
Reduction in purchase price payable		1,600
Gain on sale of mineral rights		2,100
Consideration paid		68,300
Closing cost on asset acquisition		1,600
Amount reduced the cash investment related to this transaction					$ 11,738
Relinquishment cost on prepaid royalties		1,600
Amount paid to a mineral owner as part of the acquisition		100
Ramaco Coal Asset Acquisition | Mining property and mineral rights
Asset Acquisition
Fair value of assets		65,100
Ramaco Coal Asset Acquisition | Building
Asset Acquisition
Fair value of assets		2,600
Ramaco Coal Asset Acquisition | Equipment
Asset Acquisition
Fair value of assets		$ 600
Maben Coal LLC
Asset Acquisition
Purchase price	$ 30,000
Initial payment	$ 9,000
Area of Real Estate Property | a	28
Consideration paid	$ 33,000
Closing cost on asset acquisition	1,700
Liabilities recognized	1,300
Amount of cash bond replacement obligations incurred by the Company as part of the transaction	1,200
Amount reduced the cash investment related to this transaction	10,700
Aggregate principal amount	21,000
Maben Coal LLC | Mining property and mineral rights
Asset Acquisition
Consideration paid	30,600
Maben Coal LLC | Capitalized mine development cost
Asset Acquisition
Consideration paid	1,000
Maben Coal LLC | Cash bond replacement
Asset Acquisition
Consideration paid	1,200
Maben Coal LLC | Recoupable royalties
Asset Acquisition
Consideration paid	$ 200
Coronado Global Resources Inc.
Asset Acquisition
Purchase price			$ 30,000
Closing cost on asset acquisition				$ 600
Asset acquisition, capacity of coal preparation plant | MT					1.3