Note 3 - Revenue - Revenue (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Total Revenue from Contracts with Customers		$ 214,292	$ 321,444	$ 610,688	$ 1,049,609
Coal Revenue [Member]
Total Revenue from Contracts with Customers	[1]	184,375	301,542	542,140	984,665
Terminal Revenue [Member]
Total Revenue from Contracts with Customers		17,008	16,303	49,407	50,829
Freight Revenue [Member]
Total Revenue from Contracts with Customers		$ 12,909	$ 3,599	$ 19,141	$ 14,115

[1] For the three and nine months ended September 30, 2020 and 2019, the PAMC segment had revenues from the following customers, each comprising over 10% of the Company's total sales: