GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION - Statement of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Condensed Statement of Income Captions [Line Items]
Net Income (Loss)	$ 70,958	$ 46,445
Other Comprehensive (Loss) Income:
Net Actuarial Loss (Gain)	3,997	3,414
Other Comprehensive Income	3,997	3,414
Comprehensive Income	74,955	49,859
Less: Comprehensive Income Attributable to Noncontrolling Interest	8,548	5,452
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	66,407	44,407
Elimination
Condensed Statement of Income Captions [Line Items]
Net Income (Loss)	(77,636)	(35,543)
Other Comprehensive (Loss) Income:
Net Actuarial Loss (Gain)	0	(39)
Other Comprehensive Income	0	(39)
Comprehensive Income	(77,636)	(35,582)
Less: Comprehensive Income Attributable to Noncontrolling Interest	8,548	5,452
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	(86,184)	(41,034)
Parent Issuer | Reportable Legal Entities
Condensed Statement of Income Captions [Line Items]
Net Income (Loss)	62,408	40,981
Other Comprehensive (Loss) Income:
Net Actuarial Loss (Gain)	3,999	3,414
Other Comprehensive Income	3,999	3,414
Comprehensive Income	66,407	44,395
Less: Comprehensive Income Attributable to Noncontrolling Interest	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	66,407	44,395
Guarantor | Reportable Legal Entities
Condensed Statement of Income Captions [Line Items]
Net Income (Loss)	62,789	26,941
Other Comprehensive (Loss) Income:
Net Actuarial Loss (Gain)	0	0
Other Comprehensive Income	0	0
Comprehensive Income	62,789	26,941
Less: Comprehensive Income Attributable to Noncontrolling Interest	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	62,789	26,941
Non-Guarantor | Reportable Legal Entities
Condensed Statement of Income Captions [Line Items]
Net Income (Loss)	(695)	0
Other Comprehensive (Loss) Income:
Net Actuarial Loss (Gain)	0	0
Other Comprehensive Income	0	0
Comprehensive Income	(695)	0
Less: Comprehensive Income Attributable to Noncontrolling Interest	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	(695)	0
Non-Guarantor | Reportable Legal Entities | CCR Non-Guarantor
Condensed Statement of Income Captions [Line Items]
Net Income (Loss)	24,092	14,066
Other Comprehensive (Loss) Income:
Net Actuarial Loss (Gain)	(2)	39
Other Comprehensive Income	(2)	39
Comprehensive Income	24,090	14,105
Less: Comprehensive Income Attributable to Noncontrolling Interest	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	$ 24,090	$ 14,105