Note 16 - Coal Workers' Pneumoconiosis and Workers' Compensation - Schedule of Expected Benefit Payments (Details) $ in Thousands	Dec. 31, 2020 USD ($)
2021	$ 10,580
2022	10,392
2023	10,212
2024	10,151
2025	10,015
Year 2026-2030	50,445
Coal Workers Pneumoconiosis [Member]
2021	12,203
2022	11,923
2023	11,762
2024	11,439
2025	11,304
Year 2026-2030	57,386
Actuarial Benefits [Member]
2021	9,051
2022	8,824
2023	8,605
2024	8,504
2025	8,327
Year 2026-2030	41,350
Other Benefits [Member]
2021	1,529
2022	1,568
2023	1,607
2024	1,647
2025	1,688
Year 2026-2030	$ 9,095

Amount of benefit for defined benefit plan expected to be paid in five fiscal years after fifth fiscal year following current fiscal year.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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