Guarantor Subsidiaries Financial Information (Guarantor Subsidiaries Comprehensive Income Statement) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Statement of Income Captions [Line Items]
Net Income	$ 46,034	$ 9,084	$ 52,709	$ 70,958	$ (24,640)	$ 8,518	$ 52,246	$ 46,445	$ 178,785	$ 82,569	$ 50,450
Other Comprehensive Income (Loss):
Net Actuarial Loss (Gain)									66,341	94,919	(31,409)
Other Comprehensive Income (Loss)									66,341	94,919	(31,409)
Comprehensive Income									245,126	177,488	19,041
Less: Comprehensive Income Attributable to Noncontrolling Interests									25,803	14,896	9,216
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders									219,323	162,592	9,825
Reportable Legal Entities | Parent Issuer
Condensed Statement of Income Captions [Line Items]
Net Income									152,976	67,629	41,496
Other Comprehensive Income (Loss):
Net Actuarial Loss (Gain)									66,341	94,919	(31,409)
Other Comprehensive Income (Loss)									66,341	94,919	(31,409)
Comprehensive Income									219,317	162,548	10,087
Less: Comprehensive Income Attributable to Noncontrolling Interests									0	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders									219,317	162,548	10,087
Reportable Legal Entities | Guarantor
Condensed Statement of Income Captions [Line Items]
Net Income									175,322	(137,236)	33,631
Other Comprehensive Income (Loss):
Net Actuarial Loss (Gain)									0	0	0
Other Comprehensive Income (Loss)									0	0	0
Comprehensive Income									175,322	(137,236)	33,631
Less: Comprehensive Income Attributable to Noncontrolling Interests									0	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders									175,322	(137,236)	33,631
Reportable Legal Entities | Non-Guarantor
Condensed Statement of Income Captions [Line Items]
Net Income									(2,481)	(1,995)	(103)
Other Comprehensive Income (Loss):
Net Actuarial Loss (Gain)									0	0	0
Other Comprehensive Income (Loss)									0	0	0
Comprehensive Income									(2,481)	(1,995)	(103)
Less: Comprehensive Income Attributable to Noncontrolling Interests									0	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders									(2,481)	(1,995)	(103)
Elimination
Condensed Statement of Income Captions [Line Items]
Net Income									(213,598)	113,707	(50,425)
Other Comprehensive Income (Loss):
Net Actuarial Loss (Gain)									1,477	(1,366)	(818)
Other Comprehensive Income (Loss)									1,477	(1,366)	(818)
Comprehensive Income									(212,121)	112,341	(51,243)
Less: Comprehensive Income Attributable to Noncontrolling Interests									25,803	14,896	9,216
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders									(237,924)	97,445	(60,459)
CONSOL Coal Resources LP | Reportable Legal Entities | Non-Guarantor
Condensed Statement of Income Captions [Line Items]
Net Income									66,566	40,464	25,851
Other Comprehensive Income (Loss):
Net Actuarial Loss (Gain)									(1,477)	1,366	818
Other Comprehensive Income (Loss)									(1,477)	1,366	818
Comprehensive Income									65,089	41,830	26,669
Less: Comprehensive Income Attributable to Noncontrolling Interests									0	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders									$ 65,089	$ 41,830	$ 26,669