Note 17 - Segment Information - Industry Segment (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Revenue		$ 292,016	$ 214,292	$ 925,998	$ 610,688
Adjusted EBITDA		66,564	68,298	257,696	165,477
Assets, Total		2,589,747	2,554,838	2,589,747	2,554,838	$ 2,523,366
Depreciation, Depletion and Amortization		55,977	54,959	168,073	156,057
Capital Expenditures		45,863	19,508	103,318	65,955
Coal Revenue [Member]
Revenue	[1]	258,560	184,375	803,927	542,140
Terminal Revenue [Member]
Revenue		14,108	17,008	49,700	49,407
Freight Revenue [Member]
Revenue		19,348	12,909	72,371	19,141
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		275,674	196,975	871,645	560,686
Adjusted EBITDA		69,492	45,272	246,943	135,732
Assets, Total		1,763,319	1,878,350	1,763,319	1,878,350
Depreciation, Depletion and Amortization		50,837	49,944	155,787	145,154
Capital Expenditures		30,665	15,733	83,118	52,687
Pennsylvania Mining Complex [Member] | Operating Segments [Member] | Coal Revenue [Member]
Revenue	[1]	256,326	184,066	799,274	541,545
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		19,348	12,909	72,371	19,141
CONSOL Marine Terminal [Member] | Operating Segments [Member]
Revenue		14,108	17,008	49,700	49,407
Adjusted EBITDA		7,319	11,342	30,244	32,556
Assets, Total		105,134	105,405	105,134	105,405
Depreciation, Depletion and Amortization		1,202	1,283	3,616	3,800
Capital Expenditures		453	740	565	1,360
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		14,108	17,008	49,700	49,407
CONSOL Marine Terminal [Member] | Operating Segments [Member] | Freight Revenue [Member]
Revenue		0	0	0	0
Other Segments [Member] | Operating Segments [Member]
Revenue		2,234	309	4,653	595
Adjusted EBITDA		(10,247)	11,684	(19,491)	(2,811)
Assets, Total		721,294	571,083	721,294	571,083
Depreciation, Depletion and Amortization		3,938	3,732	8,670	7,103
Capital Expenditures		14,745	3,035	19,635	11,908
Other Segments [Member] | Operating Segments [Member] | Coal Revenue [Member]
Revenue	[1]	2,234	309	4,653	595
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 September 30, 2021 and 2020, the PAMC segment had revenues from the following customers, each comprising over 10% of the Company's total sales