Note 1 - Significant Accounting Policies - Schedule of Basic and Dilutive Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net (Loss) Income		$ (13,214)	$ 93,558	$ 178,785
Less: Net (Loss) Income Attributable to Noncontrolling Interest		(3,459)	17,557	25,809
Net (Loss) Income Attributable to CONSOL Energy Inc. Shareholders		$ (9,755)	$ 76,001	$ 152,976
Weighted-average shares of common stock outstanding (in shares)		26,066,971	26,938,339	27,928,245
Effect of dilutive shares * (in shares)	[1]	0	132,769	491,517
Weighted-average diluted shares of common stock outstanding (in shares)		26,066,971	27,071,108	28,419,762
Basic (in dollars per share)		$ (0.37)	$ 2.82	$ 5.48
Dilutive (in dollars per share)		$ (0.37)	$ 2.81	$ 5.38

[1] During periods in which the Company incurs a net loss, diluted weighted average shares outstanding are equal to basic weighted average shares outstanding because the effect of all equity awards is anti-dilutive.