Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Cumulative Effect, Period of Adoption, Adjustment [Member] Common Stock [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Additional Paid-in Capital [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Retained Earnings [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] AOCI Attributable to Parent [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Parent [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Noncontrolling Interest [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member]	CONSOL Coal Resources L P Member Common Stock [Member]	CONSOL Coal Resources L P Member Additional Paid-in Capital [Member]	CONSOL Coal Resources L P Member Retained Earnings [Member]	CONSOL Coal Resources L P Member AOCI Attributable to Parent [Member]	CONSOL Coal Resources L P Member Parent [Member]	CONSOL Coal Resources L P Member Noncontrolling Interest [Member]	CONSOL Coal Resources L P Member	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Parent [Member]	Noncontrolling Interest [Member]	Total
Balance at Dec. 31, 2018															$ 274	$ 550,995	$ 182,148	$ (323,482)	$ 409,935	$ 141,676	$ 551,611
Net Income (loss)															0	0	14,435	0	14,435	5,868	20,303
Actuarially Determined Long-Term Liability Adjustments															0	0	0	2,461	2,461	(1)	2,460
Comprehensive Income															0	0	14,435	2,461	16,896	5,867	22,763
Issuance of Common Stock															2		0	0	0	0	0
Issuance of Common Stock																(2)
Amortization of Stock-Based Compensation Awards															0	7,053	0	0	7,053		7,450
Amortization of Stock-Based Compensation Awards																				397
Shares/Units Withheld for Taxes															0	(3,863)	0	0	(3,863)	(880)	(4,743)
Distributions to Noncontrolling Interest															0	0	0	0	0	(5,559)	(5,559)
Balance at Mar. 31, 2019															276	554,183	196,583	(321,021)	430,021	141,501	571,522
Balance at Dec. 31, 2018															274	550,995	182,148	(323,482)	409,935	141,676	551,611
Net Income (loss)																					76,157
Actuarially Determined Long-Term Liability Adjustments																					7,376
Interest Rate Hedge																					(525)
Comprehensive Income																					83,008
Balance at Sep. 30, 2019															259	524,896	245,957	(316,626)	454,486	138,961	593,447
Balance at Mar. 31, 2019															276	554,183	196,583	(321,021)	430,021	141,501	571,522
Net Income (loss)															0	0	43,280	0	43,280	5,550	48,830
Actuarially Determined Long-Term Liability Adjustments															0	0	0	2,460	2,460	(1)	2,459
Interest Rate Hedge															0	0	0	(264)	(264)	0	(264)
Comprehensive Income															0	0	43,280	2,196	45,476	5,549	51,025
Amortization of Stock-Based Compensation Awards															0	2,584	0	0	2,584		2,925
Amortization of Stock-Based Compensation Awards																				341
Distributions to Noncontrolling Interest															0	0	0	0	0	(5,560)	(5,560)
Balance at Jun. 30, 2019															273	549,686	237,369	(318,825)	468,503	141,740	610,243
Repurchases of Common Stock															(3)	(7,053)	(2,494)	0	(9,550)	0	(9,550)
Purchases of CCR Units								$ 0	$ (28)	$ 0	$ 0	$ (28)	$ (91)	$ (119)
Net Income (loss)															0	0	4,340	0	4,340	2,684	7,024
Actuarially Determined Long-Term Liability Adjustments															0	0	0	2,460	2,460	(3)	2,457
Interest Rate Hedge															0	0	0	(261)	(261)	0	(261)
Comprehensive Income															0	0	4,340	2,199	6,539	2,681	9,220
Amortization of Stock-Based Compensation Awards															0	2,630	0	0	2,630		2,974
Amortization of Stock-Based Compensation Awards																				344
Shares/Units Withheld for Taxes															0	(2)	0	0	(2)	0	(2)
Distributions to Noncontrolling Interest															0	0	0	0	0	(5,555)	(5,555)
Balance at Sep. 30, 2019															259	524,896	245,957	(316,626)	454,486	138,961	593,447
Repurchases of Common Stock															(14)	(27,417)		0	(23,183)	0	(23,183)
Purchases of CCR Units															0	(1)	0	0	(1)	(249)	(250)
Repurchases of Common Stock, retained earnings																	4,248
Balance at Dec. 31, 2019															259	523,762	259,903	(348,725)	435,199	137,196	572,395
Net Income (loss)															0	0	2,367	0	2,367	108	2,475
Actuarially Determined Long-Term Liability Adjustments															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															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
Amortization of Stock-Based Compensation Awards																				158
Shares/Units Withheld for Taxes															0	(555)	0	0	(555)	(217)	(772)
Distributions to Noncontrolling Interest															0	0	0	0	0	(5,575)	(5,575)
Balance (Accounting Standards Update 2016-13 [Member]) at Mar. 31, 2020	$ 0	$ 0	$ (3,298)	$ 0	$ (3,298)	$ 0	$ (3,298)
Balance at Mar. 31, 2020															260	528,062	258,972	(347,889)	439,405	131,685	571,090
Balance at Dec. 31, 2019															259	523,762	259,903	(348,725)	435,199	137,196	572,395
Net Income (loss)																					(27,948)
Actuarially Determined Long-Term Liability Adjustments																					10,872
Interest Rate Hedge																					(2,408)
Comprehensive Income																					(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)															0	0	(17,983)	0	(17,983)	(3,080)	(21,063)
Actuarially Determined Long-Term Liability Adjustments															0	0	0	3,609	3,609	15	3,624
Interest Rate Hedge															0	0	0	(12)	(12)	0	(12)
Comprehensive Income															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
Amortization of Stock-Based Compensation Awards																				74
Balance at Jun. 30, 2020															260	530,224	240,989	(344,292)	427,181	128,694	555,875
Net Income (loss)															0	0	(7,224)	0	(7,224)	(2,136)	(9,360)
Actuarially Determined Long-Term Liability Adjustments															0	0	0	3,609	3,609	15	3,624
Interest Rate Hedge															0	0	0	377	377	0	377
Comprehensive Income															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
Amortization of Stock-Based Compensation Awards																				76
Balance at Sep. 30, 2020															$ 260	$ 532,360	$ 233,765	$ (340,306)	$ 426,079	$ 126,649	$ 552,728