Guarantor Subsidiaries Financial Information (Guarantor Subsidiaries Comprehensive Income Statement) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Statement of Income Captions [Line Items]
Net Income	$ 17,401	$ 7,024	$ 48,830	$ 20,303	$ 46,034	$ 9,084	$ 52,709	$ 70,958	$ 93,558	$ 178,785	$ 82,569
Other Comprehensive Income (Loss):
Net Actuarial (Loss) Gain									(25,132)	66,341	94,919
Net unrealized loss									(117)	0	0
Other Comprehensive (Loss) Income									(25,249)	66,341	94,919
Comprehensive Income (Loss)									68,309	245,126	177,488
Less: Comprehensive Income Attributable to Noncontrolling Interest									17,551	25,803	14,896
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders									50,758	219,323	162,592
Reportable Legal Entities | Parent Issuer
Condensed Statement of Income Captions [Line Items]
Net Income									76,001	152,976	67,629
Other Comprehensive Income (Loss):
Net Actuarial (Loss) Gain									(25,132)	66,341	94,919
Net unrealized loss									(117)
Other Comprehensive (Loss) Income									(25,249)	66,341	94,919
Comprehensive Income (Loss)									50,752	219,317	162,548
Less: Comprehensive Income Attributable to Noncontrolling Interest									0	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders									50,752	219,317	162,548
Reportable Legal Entities | Guarantor
Condensed Statement of Income Captions [Line Items]
Net Income									75,213	175,322	(137,236)
Other Comprehensive Income (Loss):
Net Actuarial (Loss) Gain									0	0	0
Net unrealized loss									0
Other Comprehensive (Loss) Income									0	0	0
Comprehensive Income (Loss)									75,213	175,322	(137,236)
Less: Comprehensive Income Attributable to Noncontrolling Interest									0	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders									75,213	175,322	(137,236)
Reportable Legal Entities | Non-Guarantor
Condensed Statement of Income Captions [Line Items]
Net Income									36,796	(2,481)	(1,995)
Other Comprehensive Income (Loss):
Net Actuarial (Loss) Gain									0	0	0
Net unrealized loss									0
Other Comprehensive (Loss) Income									0	0	0
Comprehensive Income (Loss)									36,796	(2,481)	(1,995)
Less: Comprehensive Income Attributable to Noncontrolling Interest									0	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders									36,796	(2,481)	(1,995)
Elimination
Condensed Statement of Income Captions [Line Items]
Net Income									(140,003)	(213,598)	113,707
Other Comprehensive Income (Loss):
Net Actuarial (Loss) Gain									1,341	1,477	(1,366)
Net unrealized loss									0
Other Comprehensive (Loss) Income									1,341	1,477	(1,366)
Comprehensive Income (Loss)									(138,662)	(212,121)	112,341
Less: Comprehensive Income Attributable to Noncontrolling Interest									17,551	25,803	14,896
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders									(156,213)	(237,924)	97,445
CCR | Reportable Legal Entities | Non-Guarantor
Condensed Statement of Income Captions [Line Items]
Net Income									45,551	66,566	40,464
Other Comprehensive Income (Loss):
Net Actuarial (Loss) Gain									(1,341)	(1,477)	1,366
Net unrealized loss									0
Other Comprehensive (Loss) Income									(1,341)	(1,477)	1,366
Comprehensive Income (Loss)									44,210	65,089	41,830
Less: Comprehensive Income Attributable to Noncontrolling Interest									0	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders									$ 44,210	$ 65,089	$ 41,830