Consolidated Statements of Stockholders' Equity (Unaudited) (Parentheticals) - USD ($) $ in Thousands	3 Months Ended
Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020
Cumulative Effect, Period of Adoption, Adjustment [Member] \| Accounting Standards Update 2016-13 [Member]
Cumulative Change in Accounting Principle, Tax						$ 1,109
CONSOL Coal Resources L P [Member]
Unrealized gain (Loss) on Cash Flow Hedges, Tax				$ 127	$ 4
Actuarially Determined Long-Term Liability Adjustments, Tax	$ 1,164	$ 1,427	$ 1,164	1,214	(1,214)	1,214
Interest Rate Hedge, Tax	135	135	144			933
Actuarially Determined Long-Term Liability Adjustments, Tax	(1,164)	$ (1,427)	$ (1,164)	(1,214)	$ 1,214	$ (1,214)
Unrealized gain (Loss) on Cash Flow Hedges, Tax	$ (135)			$ (127)

Amount of cumulative tax effect on beginning retained earnings from change in accounting principle.

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Amount, after reclassification, of tax expense (benefit) for gain (loss) from derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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