Note 1 - Basis of Presentation - Schedule of Basic and Dilutive Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Net Income (loss)	$ (21,063)	$ 2,475	$ 48,830	$ 20,303	$ (18,588)	$ 69,133
Less: Net (Loss) Income Attributable to Noncontrolling Interest	(3,080)		5,550		(2,972)	11,418
Net (Loss) Income Attributable to CONSOL Energy Inc. Shareholders	$ (17,983)		$ 43,280		$ (15,616)	$ 57,715
Weighted-average shares of common stock outstanding (in shares)	26,031,103		27,498,021		26,009,129	27,514,349
Effect of dilutive shares* (in shares)	0		284,259		0	270,454
Weighted-average diluted shares of common stock outstanding (in shares)	26,031,103		27,782,280		26,009,129	27,784,803
Basic (in dollars per share)	$ (0.69)		$ 1.57		$ (0.60)	$ 2.10
Dilutive (in dollars per share)	$ (0.69)		$ 1.56		$ (0.60)	$ 2.08