GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION - Statement of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Statement of Income Captions [Line Items]
Net Income	$ 9,084	$ 8,518	$ 132,751	$ 107,209
Other Comprehensive Income (Loss):
Actuarially Determined Long-Term Liability Adjustments (Net of tax: ($1,232), ($1,893), ($3,697), ($5,679))	4,177	3,285	12,356	9,855
Other Comprehensive Income	4,177	3,285	12,356	9,855
Comprehensive Income	13,261	11,803	145,107	117,064
Less: Comprehensive Income Attributable to Noncontrolling Interest	3,346	779	19,444	10,533
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	9,915	11,024	125,663	106,531
Elimination
Condensed Statement of Income Captions [Line Items]
Net Income	(19,242)	(81,205)	(160,079)	(95,177)
Other Comprehensive Income (Loss):
Actuarially Determined Long-Term Liability Adjustments (Net of tax: ($1,232), ($1,893), ($3,697), ($5,679))	2	39	6	118
Other Comprehensive Income	2	39	6	118
Comprehensive Income	(19,240)	(81,166)	(160,073)	(95,059)
Less: Comprehensive Income Attributable to Noncontrolling Interest	3,346	779	19,444	10,533
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	(22,586)	(81,945)	(179,517)	(105,592)
Parent Issuer | Reportable Legal Entities
Condensed Statement of Income Captions [Line Items]
Net Income	5,734	7,728	113,304	96,642
Other Comprehensive Income (Loss):
Actuarially Determined Long-Term Liability Adjustments (Net of tax: ($1,232), ($1,893), ($3,697), ($5,679))	4,177	3,285	12,356	9,855
Other Comprehensive Income	4,177	3,285	12,356	9,855
Comprehensive Income	9,911	11,013	125,660	106,497
Less: Comprehensive Income Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	9,911	11,013	125,660	106,497
Guarantor | Reportable Legal Entities
Condensed Statement of Income Captions [Line Items]
Net Income	14,619	4,057	131,788	76,678
Other Comprehensive Income (Loss):
Actuarially Determined Long-Term Liability Adjustments (Net of tax: ($1,232), ($1,893), ($3,697), ($5,679))	0	0	0	0
Other Comprehensive Income	0	0	0	0
Comprehensive Income	14,619	4,057	131,788	76,678
Less: Comprehensive Income Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	14,619	4,057	131,788	76,678
Non-Guarantor | Reportable Legal Entities
Condensed Statement of Income Captions [Line Items]
Net Income	(672)	74,324	(2,240)	(88)
Other Comprehensive Income (Loss):
Actuarially Determined Long-Term Liability Adjustments (Net of tax: ($1,232), ($1,893), ($3,697), ($5,679))	0	0	0	0
Other Comprehensive Income	0	0	0	0
Comprehensive Income	(672)	74,324	(2,240)	(88)
Less: Comprehensive Income Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	(672)	74,324	(2,240)	(88)
Non-Guarantor | Reportable Legal Entities | CCR Non-Guarantor
Condensed Statement of Income Captions [Line Items]
Net Income	8,645	3,614	49,978	29,154
Other Comprehensive Income (Loss):
Actuarially Determined Long-Term Liability Adjustments (Net of tax: ($1,232), ($1,893), ($3,697), ($5,679))	(2)	(39)	(6)	(118)
Other Comprehensive Income	(2)	(39)	(6)	(118)
Comprehensive Income	8,643	3,575	49,972	29,036
Less: Comprehensive Income Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	$ 8,643	$ 3,575	$ 49,972	$ 29,036