Note 17 - Segment Information - Industry Segment (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Revenue		$ 303,222	$ 121,296	$ 633,982	$ 396,396
Adjusted EBITDA		84,417	34,245	191,132	97,179
Assets, Total		2,557,931	2,566,132	2,557,931	2,566,132	$ 2,523,366
Depreciation, Depletion and Amortization		52,199	46,155	112,096	101,098
Capital Expenditures		43,655	19,269	57,455	46,447
Coal Revenue [Member]
Revenue	[1]	259,832	102,313	545,367	357,765
Terminal Revenue [Member]
Revenue		17,380	15,898	35,592	32,399
Freight Revenue [Member]
Revenue		26,010	3,085	53,023	6,232
Intersegment Eliminations [Member]
Revenue		0	0	0	0
Adjusted EBITDA		0	0	0	0
Assets, Total		0	0	0	0
Depreciation, Depletion and Amortization		0	0	0	0
Capital Expenditures		0	0	0	0
Intersegment Eliminations [Member] | Coal Revenue [Member]
Revenue	[1]	0	0	0	0
Intersegment Eliminations [Member] | Terminal Revenue [Member]
Revenue		0	0	0	0
Intersegment Eliminations [Member] | Freight Revenue [Member]
Revenue		0	0	0	0
Pennsylvania Mining Complex [Member] | Operating Segments [Member]
Revenue		284,492	105,111	595,971	363,710
Adjusted EBITDA		78,267	26,882	177,451	90,460
Assets, Total		1,799,848	1,889,557	1,799,848	1,889,557
Depreciation, Depletion and Amortization		50,169	46,793	104,950	95,210
Capital Expenditures		39,874	16,262	52,453	36,954
Pennsylvania Mining Complex [Member] | Operating Segments [Member] | Coal Revenue [Member]
Revenue	[1]	258,482	102,026	542,948	357,478
Pennsylvania Mining Complex [Member] | Operating Segments [Member] | Terminal Revenue [Member]
Revenue		0	0	0	0
Pennsylvania Mining Complex [Member] | Operating Segments [Member] | Freight Revenue [Member]
Revenue		26,010	3,085	53,023	6,232
CONSOL Marine Terminal [Member] | Operating Segments [Member]
Revenue		17,380	15,898	35,592	32,399
Adjusted EBITDA		10,965	10,660	22,926	21,214
Assets, Total		104,848	99,942	104,848	99,942
Depreciation, Depletion and Amortization		1,200	1,260	2,414	2,517
Capital Expenditures		52	514	112	620
CONSOL Marine Terminal [Member] | Operating Segments [Member] | Coal Revenue [Member]
Revenue	[1]	0	0	0	0
CONSOL Marine Terminal [Member] | Operating Segments [Member] | Terminal Revenue [Member]
Revenue		17,380	15,898	35,592	32,399
CONSOL Marine Terminal [Member] | Operating Segments [Member] | Freight Revenue [Member]
Revenue		0	0	0	0
Other Segments [Member] | Operating Segments [Member]
Revenue		1,350	287	2,419	287
Adjusted EBITDA		(4,815)	(3,297)	(9,245)	(14,495)
Assets, Total		653,235	576,633	653,235	576,633
Depreciation, Depletion and Amortization		830	(1,898)	4,732	3,371
Capital Expenditures		3,729	2,493	4,890	8,873
Other Segments [Member] | Operating Segments [Member] | Coal Revenue [Member]
Revenue	[1]	1,350	287	2,419	287
Other Segments [Member] | Operating Segments [Member] | Terminal Revenue [Member]
Revenue		0	0	0	0
Other Segments [Member] | Operating Segments [Member] | Freight Revenue [Member]
Revenue		$ 0	$ 0	$ 0	$ 0

[1] For the three and six months ended June 30, 2021 and 2020, the PAMC segment had revenues from the following customers, each comprising over 10% of the Company's total sales