GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION - Statement of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Condensed Statement of Income Captions [Line Items]
Net Income	$ 52,709	$ 52,246	$ 123,667	$ 98,690
Other Comprehensive (Loss) Income:
Actuarially Determined Long-Term Liability Adjustments (Net of tax: ($1,183), ($1,819), ($2,464), ($3,786))	4,182	3,155	8,179	6,569
Other Comprehensive Income	4,182	3,155	8,179	6,569
Comprehensive Income	56,891	55,401	131,846	105,259
Less: Comprehensive Income Attributable to Noncontrolling Interest	7,550	4,302	16,098	9,754
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	49,341	51,099	115,748	95,505
Elimination
Condensed Statement of Income Captions [Line Items]
Net Income	(65,144)	21,570	(140,837)	(13,972)
Other Comprehensive (Loss) Income:
Actuarially Determined Long-Term Liability Adjustments (Net of tax: ($1,183), ($1,819), ($2,464), ($3,786))	0	0	0	1,366
Other Comprehensive Income	0	0	0	1,366
Comprehensive Income	(65,144)	21,570	(140,837)	(12,606)
Less: Comprehensive Income Attributable to Noncontrolling Interest	7,550	4,302	16,098	9,754
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	(72,694)	17,268	(156,935)	(22,360)
Parent Issuer | Reportable Legal Entities
Condensed Statement of Income Captions [Line Items]
Net Income	45,162	47,933	107,570	88,913
Other Comprehensive (Loss) Income:
Actuarially Determined Long-Term Liability Adjustments (Net of tax: ($1,183), ($1,819), ($2,464), ($3,786))	4,184	3,155	8,183	6,569
Other Comprehensive Income	4,184	3,155	8,183	6,569
Comprehensive Income	49,346	51,088	115,753	95,482
Less: Comprehensive Income Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	49,346	51,088	115,753	95,482
Guarantor | Reportable Legal Entities
Condensed Statement of Income Captions [Line Items]
Net Income	54,188	45,681	117,169	72,621
Other Comprehensive (Loss) Income:
Actuarially Determined Long-Term Liability Adjustments (Net of tax: ($1,183), ($1,819), ($2,464), ($3,786))	0	0	0	0
Other Comprehensive Income	0	0	0	0
Comprehensive Income	54,188	45,681	117,169	72,621
Less: Comprehensive Income Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	54,188	45,681	117,169	72,621
Non-Guarantor | Reportable Legal Entities
Condensed Statement of Income Captions [Line Items]
Net Income	(873)	(74,412)	(1,568)	(74,412)
Other Comprehensive (Loss) Income:
Actuarially Determined Long-Term Liability Adjustments (Net of tax: ($1,183), ($1,819), ($2,464), ($3,786))	0	0	0	0
Other Comprehensive Income	0	0	0	0
Comprehensive Income	(873)	(74,412)	(1,568)	(74,412)
Less: Comprehensive Income Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	(873)	(74,412)	(1,568)	(74,412)
Non-Guarantor | Reportable Legal Entities | CCR Non-Guarantor
Condensed Statement of Income Captions [Line Items]
Net Income	19,376	11,474	41,333	25,540
Other Comprehensive (Loss) Income:
Actuarially Determined Long-Term Liability Adjustments (Net of tax: ($1,183), ($1,819), ($2,464), ($3,786))	(2)	0	(4)	(1,366)
Other Comprehensive Income	(2)	0	(4)	(1,366)
Comprehensive Income	19,374	11,474	41,329	24,174
Less: Comprehensive Income Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders	$ 19,374	$ 11,474	$ 41,329	$ 24,174