Note 2 - Revenue - Revenue (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Total Revenue from Contracts with Customers		$ 121,296	$ 371,182	$ 396,396	$ 728,165
Coal Revenue [Member]
Total Revenue from Contracts with Customers	[1]	102,313	350,620	357,765	683,123
Terminal Revenue [Member]
Total Revenue from Contracts with Customers		15,898	16,708	32,399	34,526
Freight Revenue [Member]
Total Revenue from Contracts with Customers		$ 3,085	$ 3,854	$ 6,232	$ 10,516

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