Note 16 - Segment Information - Industry Segment (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Revenue		$ 330,760	$ 275,100
Adjusted EBITDA		106,715	62,934
Assets, Total		2,520,560	2,653,468	$ 2,523,366
Depreciation, Depletion and Amortization		59,897	54,943
Capital Expenditures		13,800	27,178
Coal Revenue [Member]
Revenue	[1]	285,535	255,452
Terminal Revenue [Member]
Revenue		18,212	16,501
Freight Revenue [Member]
Revenue		27,013	3,147
Intersegment Eliminations [Member]
Revenue		0	0
Adjusted EBITDA		0	0
Assets, Total		0	0
Depreciation, Depletion and Amortization		0	0
Capital Expenditures		0	0
Intersegment Eliminations [Member] | Coal Revenue [Member]
Revenue	[1]	0	0
Intersegment Eliminations [Member] | Terminal Revenue [Member]
Revenue		0	0
Intersegment Eliminations [Member] | Freight Revenue [Member]
Revenue		0	0
Pennsylvania Mining Complex [Member] | Operating Segments [Member]
Revenue		311,478	258,599
Adjusted EBITDA		99,185	63,579
Assets, Total		1,855,878	1,949,655
Depreciation, Depletion and Amortization		54,781	48,418
Capital Expenditures		12,579	20,692
Pennsylvania Mining Complex [Member] | Operating Segments [Member] | Coal Revenue [Member]
Revenue	[1]	284,465	255,452
Pennsylvania Mining Complex [Member] | Operating Segments [Member] | Terminal Revenue [Member]
Revenue		0	0
Pennsylvania Mining Complex [Member] | Operating Segments [Member] | Freight Revenue [Member]
Revenue		27,013	3,147
CONSOL Marine Terminal [Member] | Operating Segments [Member]
Revenue		18,212	16,501
Adjusted EBITDA		11,961	10,554
Assets, Total		106,603	86,036
Depreciation, Depletion and Amortization		1,214	1,257
Capital Expenditures		60	106
CONSOL Marine Terminal [Member] | Operating Segments [Member] | Coal Revenue [Member]
Revenue	[1]	0	0
CONSOL Marine Terminal [Member] | Operating Segments [Member] | Terminal Revenue [Member]
Revenue		18,212	16,501
CONSOL Marine Terminal [Member] | Operating Segments [Member] | Freight Revenue [Member]
Revenue		0	0
Other Segments [Member] | Operating Segments [Member]
Revenue		1,070	0
Adjusted EBITDA		(4,431)	(11,199)
Assets, Total		558,079	617,777
Depreciation, Depletion and Amortization		3,902	5,268
Capital Expenditures		1,161	6,380
Other Segments [Member] | Operating Segments [Member] | Coal Revenue [Member]
Revenue	[1]	1,070	0
Other Segments [Member] | Operating Segments [Member] | Terminal Revenue [Member]
Revenue		0	0
Other Segments [Member] | Operating Segments [Member] | Freight Revenue [Member]
Revenue		$ 0	$ 0

[1] For the three months ended March 31, 2021 and 2020, the PAMC segment had revenues from the following customers, each comprising over 10% of the Company's total sales: Three Months Ended March 31, 2021 2020 Customer A $ 57,680 $ 38,908 Customer B $ 33,239 $ 104,354 Customer C $ 36,599 $ 35,683 Customer D $ 44,236 *