Note 24 - Segment Information - Segment Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020		Dec. 31, 2019
Revenue	$ 1,261,034	$ 879,462		$ 1,375,559
Revenue Benchmark [Member] | Pennsylvania Mining Complex [Member] | Customer Concentration Risk [Member] | Customer A [Member]
Revenue	186,622	134,354	[1]	242,702
Revenue Benchmark [Member] | Pennsylvania Mining Complex [Member] | Customer Concentration Risk [Member] | Customer B [Member]
Revenue		223,891		507,099
Revenue Benchmark [Member] | Pennsylvania Mining Complex [Member] | Customer Concentration Risk [Member] | Customer C [Member]
Revenue	141,968	$ 116,536		$ 215,099
Revenue Benchmark [Member] | Pennsylvania Mining Complex [Member] | Customer Concentration Risk [Member] | Customer D [Member]
Revenue	$ 170,901

[1] Revenues from these customers during the periods presented were less than 10% of the Company's total sales.