Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Common Stock [Member] CONSOL Coal Resources L P [Member]	Common Stock [Member]	Additional Paid-in Capital [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Additional Paid-in Capital [Member] CONSOL Coal Resources L P [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Retained Earnings [Member] CONSOL Coal Resources L P [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	AOCI Attributable to Parent [Member] CONSOL Coal Resources L P [Member]	AOCI Attributable to Parent [Member]	Parent [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Parent [Member] CONSOL Coal Resources L P [Member]	Parent [Member]	Noncontrolling Interest [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Noncontrolling Interest [Member] CONSOL Coal Resources L P [Member]	Noncontrolling Interest [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member]	CONSOL Coal Resources L P [Member]	Total
Balance at Dec. 31, 2019	$ 0		$ 259	$ 0		$ 523,762	$ (3,298)		$ 259,903	$ 0		$ (348,725)	$ (3,298)		$ 435,199	$ 0		$ 137,196	$ (3,298)		$ 572,395
Net Income (Loss)			0			0			2,367			0			2,367			108			2,475
Actuarially Determined Long-Term Liability Adjustments, Net of Tax			0			0			0			3,609			3,609			15			3,624
Interest Rate Hedge			0			0			0			(2,773)			(2,773)			0			(2,773)
Comprehensive Income (loss)			0			0			2,367			836			3,203			123			3,326
Issuance of Common Stock			1						0			0			0			0			0
Issuance of Common Stock						(1)
Amortization of Stock-Based Compensation Awards			0			4,856			0			0			4,856						5,014
Shares Withheld for Taxes			0			(555)			0			0			(555)			(217)			(772)
Comprehensive Income (loss)			0			0			2,367			836			3,203			123			3,326
Balance at Mar. 31, 2020			260			528,062			258,972			(347,889)			439,405			131,685			571,090
Amortization of Stock-Based Compensation Awards																		158
Distributions to Noncontrolling Interest			0			0			0			0			0			(5,575)			(5,575)
Balance at Dec. 31, 2019	$ 0		259	$ 0		523,762	$ (3,298)		259,903	$ 0		(348,725)	$ (3,298)		435,199	$ 0		137,196	$ (3,298)		572,395
Net Income (Loss)																					(27,948)
Interest Rate Hedge																					(2,408)
Comprehensive Income (loss)																					(19,484)
Comprehensive Income (loss)																					(19,484)
Balance at Sep. 30, 2020			260			532,360			233,765			(340,306)			426,079			126,649			552,728
Balance at Mar. 31, 2020			260			528,062			258,972			(347,889)			439,405			131,685			571,090
Net Income (Loss)									(17,983)						(17,983)			(3,080)			(21,063)
Actuarially Determined Long-Term Liability Adjustments, Net of Tax			0			0			0			3,609			3,609			15			3,624
Interest Rate Hedge		$ 0			$ 0			$ 0			$ (12)			$ (12)			$ 0			$ (12)
Comprehensive Income (loss)		0			0			(17,983)			3,597			(14,386)			(3,065)				(17,451)
Amortization of Stock-Based Compensation Awards			0			2,162			0			0			2,162						2,236
Comprehensive Income (loss)		0			0			(17,983)			3,597			(14,386)			(3,065)				(17,451)
Balance at Jun. 30, 2020			260			530,224			240,989			(344,292)			427,181			128,694			555,875
Amortization of Stock-Based Compensation Awards																		74
Net Income (Loss)			0			0			(7,224)			0			(7,224)			(2,136)			(9,360)
Actuarially Determined Long-Term Liability Adjustments, Net of Tax			0			0			0			3,609			3,609			15			3,624
Interest Rate Hedge																					377
Comprehensive Income (loss)			0			0			(7,224)			3,986			(3,238)			(2,121)			(5,359)
Amortization of Stock-Based Compensation Awards			0			2,136			0			0			2,136						2,212
CCR Merger		0			0			0			377			$ 377			$ 0			377
Comprehensive Income (loss)			0			0			(7,224)			3,986			(3,238)			(2,121)			(5,359)
Balance at Sep. 30, 2020			260			532,360			233,765			(340,306)			$ 426,079			126,649			552,728
Amortization of Stock-Based Compensation Awards																		$ 76
Balance at Dec. 31, 2020			340			642,887			246,850			(336,558)									553,519
Net Income (Loss)			0			0			26,404			0									26,404
Actuarially Determined Long-Term Liability Adjustments, Net of Tax			0			0			0			3,360									3,360
Interest Rate Hedge			0			0			0			414									414
Comprehensive Income (loss)			0			0			26,404			3,774									30,178
Issuance of Common Stock			4						0			0									0
Issuance of Common Stock						(4)
Amortization of Stock-Based Compensation Awards			0			1,509			0			0									1,509
Shares Withheld for Taxes			0			(2,072)			0			0									(2,072)
CCR Merger		$ 0			$ (266)			$ 0			$ 197									$ (69)
Comprehensive Income (loss)			0			0			26,404			3,774									30,178
Balance at Mar. 31, 2021			344			642,054			273,254			(332,587)									583,065
Balance at Dec. 31, 2020			340			642,887			246,850			(336,558)									553,519
Net Income (Loss)																					(83,213)
Interest Rate Hedge																					1,195
Comprehensive Income (loss)																					(71,174)
Comprehensive Income (loss)																					(71,174)
Balance at Sep. 30, 2021			345			644,920			163,637			(324,322)									484,580
Balance at Mar. 31, 2021			344			642,054			273,254			(332,587)									583,065
Net Income (Loss)			0			0			4,172			0									4,172
Actuarially Determined Long-Term Liability Adjustments, Net of Tax			0			0			0			4,125									4,125
Interest Rate Hedge			0			0			0			391									391
Comprehensive Income (loss)			0			0			4,172			4,516									8,688
Issuance of Common Stock			1						0			0									0
Issuance of Common Stock						(1)
Amortization of Stock-Based Compensation Awards			0			1,210			0			0									1,210
Shares Withheld for Taxes			0			(230)			0			0									(230)
Comprehensive Income (loss)			0			0			4,172			4,516									8,688
Balance at Jun. 30, 2021			345			643,033			277,426			(328,071)									592,733
Net Income (Loss)			0			0			(113,789)			0									(113,789)
Actuarially Determined Long-Term Liability Adjustments, Net of Tax			0			0			0			3,359									3,359
Interest Rate Hedge			0			0			0			390									390
Comprehensive Income (loss)			0			0			(113,789)			3,749									(110,040)
Amortization of Stock-Based Compensation Awards			0			1,888			0			0									1,888
Shares Withheld for Taxes			0			(1)			0			0									(1)
Comprehensive Income (loss)			0			0			(113,789)			3,749									(110,040)
Balance at Sep. 30, 2021			$ 345			$ 644,920			$ 163,637			$ (324,322)									$ 484,580