Other Income and Expenses [Abstract] Schedule of Miscellaneous Other Income Interest and Other Income [Table Text Block] Condensed Financial Information of Parent Company Only Disclosure [Abstract] Condensed Statement of Comprehensive Income [Table] Condensed Statement of Comprehensive Income [Table] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Parent Issuer Parent Company [Member] Guarantor Guarantor Subsidiaries [Member] Non-Guarantor Non-Guarantor Subsidiaries [Member] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Reportable Legal Entities Reportable Legal Entities [Member] Elimination Consolidation, Eliminations [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] CCR Non-Guarantor CONSOL Coal Resources LP [Member] CONSOL Coal Resources LP [Member] Condensed Statement of Income Captions [Line Items] Condensed Statement of Income Captions [Line Items] Net Income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Other Comprehensive Income (Loss): Other Comprehensive Income (Loss), Net of Tax [Abstract] Actuarially Determined Long-Term Liability Adjustments (Net of tax: ($1,232), ($1,893), ($3,697), ($5,679)) Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, after Tax Other Comprehensive Income Other Comprehensive Income (Loss), Net of Tax Comprehensive Income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Less: Comprehensive Income Attributable to Noncontrolling Interest Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Comprehensive Income Attributable to CONSOL Energy Inc. Shareholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent Debt Disclosure [Abstract] Schedule of Long-term Debt Schedule of Long-term Debt Instruments [Table Text Block] Accounting Policies [Abstract] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Basis of Consolidation Consolidation, Policy [Policy Text Block] Cost Allocations Cost Allocations Policy [Policy Text Block] Cost Allocations Policy [Policy Text Block] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Earnings per Share Earnings Per Share, Policy [Policy Text Block] Revenue Recognition Revenue from Contract with Customer [Policy Text Block] Revenue from Contract with Customer [Policy Text Block] Statement of Comprehensive Income [Abstract] Actuarially Determined Long-Term Liability Adjustments, Tax Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, Tax Inventory Disclosure [Abstract] Schedule of Inventory Schedule of Inventory, Current [Table Text Block] Related Party Transactions [Abstract] Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] CNX Resources Corporation CNX Resources Corporation [Member] CNX Resources Corporation [Member] CNX Coal Resources LP CNX Coal Resources LP [Member] CNX Coal Resources LP [Member] Affiliated Entity Affiliated Entity [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Senior Secured Revolving Credit Facility Senior Secured Revolving Credit Facility [Member] Senior Secured Revolving Credit Facility [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Line of Credit Line of Credit [Member] Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Affiliated Company Credit Agreement Affiliated Company Credit Agreement [Member] Affiliated Company Credit Agreement [Member] Limited Partners' Capital Account by Class [Axis] Limited Partners' Capital Account by Class [Axis] Limited Partners' Capital Account, Class [Domain] Limited Partners' Capital Account, Class [Domain] Preferred Class A Preferred Class A [Member] Consol Coal Resources LP Units Consol Coal Resources LP Units [Member] Consol Coal Resources LP Units [Member] CONSOL Thermal Holdings LLC CONSOL Thermal [Member] CONSOL Thermal [Member] CONSOL Coal Resources LP Related Party Transaction [Line Items] Related Party Transaction [Line Items] Accounts payable, related parties Accounts Payable, Related Parties Notes receivable, related parties Notes Receivable, Related Parties Other receivables - related parties Notes Receivable, Related Parties, Current Accounts receivable, related parties, noncurrent Notes Receivable, Related Parties, Noncurrent Separation and distribution costs Separation and Distribution Costs Separation and Distribution Costs Payment of separation and distribution costs Payment of Separation and Distribution Costs Payment of Separation and Distribution Costs Number of independent businesses Separation, Number Of Independent Businesses Separation, Number Of Independent Businesses Units sold in initial public offering (in shares) Partners' Capital Account, Units, Sold in Public Offering Initial public offering share price (in dollars per share) Initial Public Offering Share Price Initial Public Offering Share Price Net proceeds initial public offering Proceeds from Issuance Initial Public Offering Over-allotment option (in shares) Initial Public Offering overallotment Initial Public Offering overallotment Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Initial draw on line of credit Proceeds from Lines of Credit Origination fees Payments of Financing Costs Net proceeds line of credit Proceeds from Debt, Net of Issuance Costs Net proceeds from initial public offering Net Proceeds from Initial Public Offering Net Proceeds from Initial Public Offering Undivided interest (as a percent) Transactions Between Entities Under Common Control, Percentage of Undivided Interest Transactions Between Entities Under Common Control, Percentage of Undivided Interest Cash consideration Transactions Between Entities Under Common Control, Payments to Acquire Assets, Gross Transactions Between Entities Under Common Control, Payments to Acquire Assets, Gross Preferred units issued (in shares) Stock Issued During Period, Shares, Conversion of Convertible Securities Issue price (in dollars per share) Transactions Between Entities Under Common Control, Share Issue Price Transactions Between Entities Under Common Control, Share Issue Price Equity consideration Transactions Between Entities Under Common Control, Consideration Transferred, Equity Interest Issued and Issuable Transactions Between Entities Under Common Control, Consideration Transferred, Equity Interest Issued and Issuable Weighted average trading price (in dollars per share) Transactions Between Entities Under Common Control, Consideration Transferred, Volume Weighted-average Trading Price Per Share Transactions Between Entities Under Common Control, Consideration Transferred, Volume Weighted-average Trading Price Per Share Price premium (as a percent) Transactions Between Entities Under Common Control, Consideration Transferred, Volume Weighted-average Trading Price, Premium Transactions Between Entities Under Common Control, Consideration Transferred, Volume Weighted-average Trading Price, Premium Line of credit amount drawn Long-term Line of Credit Stated interest rate (as a percent) Debt Instrument, Interest Rate, Stated Percentage Interest expense Interest Expense, Related Party Net payable Accounts Payable, Related Parties, Current Stock and debt repurchase additional amount authorized Stock and Debt Repurchase Program, Additional Authorized Amount Stock and Debt Repurchase Program, Additional Authorized Amount Shares repurchased (in shares) Stock Repurchased During Period, Shares Average share price (in dollars per share) Treasury Stock Acquired, Average Cost Per Share Coal Inventory, Raw Materials, Net of Reserves Supplies Inventory, Supplies, Net of Reserves Total Inventories Inventory, Net Segment Reporting [Abstract] Number of reportable segments Number of Reportable Segments Income Tax Disclosure [Abstract] INCOME TAXES Income Tax Disclosure [Text Block] Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock Common Stock [Member] Capital in Excess of Par Value Additional Paid-in Capital [Member] Retained Earnings (Deficit) Retained Earnings [Member] Accumulated Other Comprehensive (Loss) Income AOCI Attributable to Parent [Member] Total CONSOL Energy Inc. Stockholders' Equity Parent [Member] Noncontrolling Interest Noncontrolling Interest [Member] Statement [Line Items] Statement [Line Items] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Actuarially Determined Long-Term Liability Adjustments (Net of $3,697 Tax) Reclassification of Stranded Tax Effect of Change in Tax Law Stockholders Equity Reclassification Adjustment, Change in Tax Law Stockholders Equity Reclassification Adjustment, Change in Tax Law Separation Adjustments Stockholders' Equity, Separation Related Adjustments Stockholders' Equity, Separation Related Adjustments Issuance of Common Stock Proceeds from Issuance of Common Stock Retirement of outstanding shares Stock Repurchased During Period, Value Amortization of Stock-Based Compensation Awards Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Units/Shares Withheld for Taxes Adjustments Related to Tax Withholding for Share-based Compensation Distributions to Noncontrolling Interest Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Ending balance Income Statement Condensed Income Statement [Table Text Block] Balance Sheet Condensed Balance Sheet [Table Text Block] Condensed Statement of Cash Flows Condensed Cash Flow Statement [Table Text Block] Statement of Comprehensive Income Condensed Statement of Comprehensive Income [Table Text Block] Net Income Other Comprehensive Income: LONG-TERM DEBT Long-term Debt [Text Block] Schedule of Revenue by Major Customers, by Reporting Segments [Table] Schedule of Revenue by Major Customers, by Reporting Segments [Table] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Sales Revenue, Goods, Net Sales Revenue, Goods, Net [Member] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Customer Concentration Risk Customer Concentration Risk [Member] Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] Customer A Customer A [Member] Customer A [Member] Customer B Customer B [Member] Customer B [Member] Customer C Customer C [Member] Customer C [Member] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] PAMC Pennsylvania Mining Complex [Member] Pennsylvania Mining Complex [Member] Revenue, Major Customer [Line Items] Revenue, Major Customer [Line Items] Revenue from contracts with customers Revenue from Contract with Customer, Excluding Assessed Tax Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Restricted cash Restricted Cash Cash and cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Short-term Debt [Abstract] Schedule of Short-term Debt [Table] Schedule of Short-term Debt [Table] Short-term Debt, Type [Axis] Short-term Debt, Type [Axis] Short-term Debt, Type [Domain] Short-term Debt, Type [Domain] Accounts Receivable Securitization Facility Accounts Receivable Securitization Facility [Member] Accounts Receivable Securitization Facility [Member] Short-term Debt [Line Items] Short-term Debt [Line Items] Security facility program fee (as a percent) Line of Credit Facility, Commitment Fee Percentage Unused commitment fee (as a percent) Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Accounts receivable eligible for securitization Accounts Receivable Eligible for Securitization Accounts Receivable Eligible for Securitization Outstanding borrowings Line of Credit Facility, Fair Value of Amount Outstanding Letters of credit outstanding Letters of Credit Outstanding, Amount Borrowings and issuance of letters of credit remaining capacity Line of Credit Facility, Remaining Borrowing Capacity Costs associated with receivables facility Statement of Cash Flows [Abstract] Term Loan A Term Loan A Facility [Member] Term Loan A Facility [Member] Term Loan B Term Loan B Facility [Member] Term Loan B Facility [Member] Senior Secured Second Lien Notes due 2025 Senior Secured Second Lien Notes due 2025 [Member] Senior Secured Second Lien Notes due 2025 [Member] Cash Flows from Operating Activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation, Depletion and Amortization Depreciation, Depletion and Amortization Gain on Sale of Assets Gain (Loss) on Disposition of Assets Stock/Unit Based Compensation Share-based Compensation Deferred Income Taxes Deferred Income Tax Expense (Benefit) Changes in Operating Assets: Increase (Decrease) in Operating Capital [Abstract] Accounts and Notes Receivable Increase (Decrease) in Accounts and Notes Receivable Inventories Increase (Decrease) in Inventories Prepaid Expenses Increase (Decrease) in Prepaid Expense Changes in Other Assets Increase (Decrease) in Other Operating Assets Changes in Operating Liabilities: Increase (Decrease) in Operating Liabilities [Abstract] Accounts Payable Increase (Decrease) in Accounts Payable Other Operating Liabilities Increase (Decrease) in Other Current Liabilities Changes in Other Liabilities Increase (Decrease) in Other Noncurrent Liabilities Other Other Operating Activities, Cash Flow Statement Net Cash Provided by Operating Activities Net Cash Provided by (Used in) Operating Activities Cash Flows from Investing Activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Capital Expenditures Payments to Acquire Productive Assets Proceeds from Sales of Assets Proceeds from Sale of Productive Assets Net Cash Used in Investing Activities Net Cash Provided by (Used in) Investing Activities Cash Flows from Financing Activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Payments on Capitalized Leases Repayments of Long-term Capital Lease Obligations Net Payments on Revolver - MLP Proceeds from (Repayments of) Lines of Credit Payments of loans Proceeds from (Repayments of) Debt Repurchases of Common Stock Payments for Repurchase of Common Stock Spin Distribution to CNX Resources Spin Distribution Spin Distribution Distributions to Noncontrolling Interest Payments to Noncontrolling Interests Other Parent Net Distributions Payments Of Distributions To Parent Payments Of Distributions To Parent Shares/Units Withheld for Taxes Payments Related to Tax Withholding for Share-based Compensation Debt-Related Financing Fees Net Cash Used in Financing Activities Net Cash Provided by (Used in) Financing Activities Net Increase (Decrease) in Cash and Cash Equivalents and Restricted Cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect Cash and Cash Equivalents and Restricted Cash at Beginning of Period Cash and Cash Equivalents and Restricted Cash at End of Period Non-Cash Investing and Financing Activities: Noncash Investing and Financing Items [Abstract] Capital Lease Capital Lease Obligations Incurred RELATED PARTY TRANSACTIONS Related Party Transactions Disclosure [Text Block] Equity [Abstract] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Senior Notes Senior Notes [Member] Senior Secured Notes due 2025 Senior Secured Notes due 2025 [Member] Senior Secured Notes due 2025 [Member] Class of Stock [Line Items] Class of Stock [Line Items] Aggregate authorized amount Stock Repurchase Program, Authorized Amount Stock and debt repurchase authorized amount Stock and Debt Repurchase Program, Authorized Amount Stock and Debt Repurchase Program, Authorized Amount Repayments of debt Repayments of Debt Subsequent Events [Abstract] SUBSEQUENT EVENTS Subsequent Events [Text Block] Retirement Benefits [Abstract] COMPONENTS OF PENSION AND OTHER POST-EMPLOYMENT BENEFIT (OPEB) PLANS NET PERIODIC BENEFIT COSTS Pension and Other Postretirement Benefits Disclosure [Text Block] ACCOUNTS RECEIVABLE SECURITIZATION Accounts Receivable Securitization [Text Block] Accounts Receivable Securitization [Text Block] Condensed Financial Statements [Table] Condensed Financial Statements [Table] Loans Payable Loans Payable [Member] Condensed Financial Statements, Captions [Line Items] Condensed Financial Statements, Captions [Line Items] Debt instrument face value Debt Instrument, Face Amount Payables and Accruals [Abstract] Schedule of Accrued Liabilities Schedule of Accrued Liabilities [Table Text Block] Schedule of Components of Net Periodic Benefit Cost Schedule of Changes in Accumulated Postemployment Benefit Obligations [Table Text Block] Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Plant and Equipment Coal And Other Plant And Equipment [Member] Coal And Other Plant And Equipment [Member] Coal Properties and Surface Lands Mining Properties and Mineral Rights [Member] Airshafts Airshafts [Member] Airshafts [Member] Mine Development Mine Development [Member] Advance Mining Royalties Coal Advance Mining Royalties [Member] Coal Advance Mining Royalties [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Total Property, Plant and Equipment Property, Plant and Equipment, Gross Less: Accumulated Depreciation, Depletion and Amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Total Property, Plant and Equipment—Net Property, Plant and Equipment, Net Gross assets under capital lease Capital Leased Assets, Gross Accumulated amortization for capital leases Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation Amortization expense for assets under capital lease Capital Leases, Income Statement, Amortization Expense COMPONENTS OF COAL WORKERS’ PNEUMOCONIOSIS (CWP) AND WORKERS’ COMPENSATION NET PERIODIC BENEFIT COSTS Pneumoconiosis Benefits And Workers Compensation Disclosure [Text Block] Pneumoconiosis Benefits And Workers Compensation Disclosure [Text Block] Fair Value Disclosures [Abstract] Schedule of Financial Instruments Measured at Fair Value Fair Value, Assets Measured on Recurring Basis [Table Text Block] Schedule of Fair Value of Financial Instruments Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block] Revenue from Contract with Customer [Abstract] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Products and Services [Axis] Products and Services [Axis] Products and Services [Domain] Products and Services [Domain] Coal Revenue Coal Revenue [Member] Coal Revenue [Member] Terminal Revenue Terminal Revenue [Member] Terminal Revenue [Member] Freight Revenue Freight Revenue [Member] Freight Revenue [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Total Revenue from Contracts with Customers STOCK, UNIT AND DEBT REPURCHASE Stockholders' Equity Note Disclosure [Text Block] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Revolving Credit Facility Revolving Credit Facility [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Scenario, Forecast Scenario, Forecast [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] First lien gross leverage ratio, maximum Debt Instrument, Covenant, First Lien Gross Leverage Ratio, Maximum Debt Instrument, Covenant, First Lien Gross Leverage Ratio First lien gross leverage ratio, actual Debt Instrument, Covenant, First Lien Gross Leverage Ratio, Actual Debt Instrument, Covenant, First Lien Gross Leverage Ratio, Actual Total net leverage ratio, maximum Debt Instrument, Covenant, Net Leverage Ratio, Maximum Debt Instrument, Covenant, Net Leverage Ratio, Maximum Total net leverage ratio, actual Debt Instrument, Covenant, Net Leverage Ratio, Actual Debt Instrument, Covenant, Net Leverage Ratio, Actual Fixed charge coverage ratio, minimum Debt Instrument, Covenant, Fixed Charge Coverage Ratio, Minimum Debt Instrument, Covenant, Fixed Charge Coverage Ratio, Minimum Fixed charge coverage ratio Debt Instrument, Covenant, Fixed Charge Coverage Ratio, Actual Debt Instrument, Covenant, Fixed Charge Coverage Ratio, Actual Letters of credit outstanding Letters Of Credit Amount Outstanding Letters Of Credit, Amount Outstanding Principal Repayment on line of credit Repayments of Lines of Credit Accelerated repayment Accelerated Repayments on Line of Credit Accelerated Repayments on Line of Credit Debt repurchased Debt Instrument, Repurchased Face Amount Loss on debt extinguishment Gain (Loss) on Extinguishment of Debt Condensed Income Statement [Table] Condensed Income Statement [Table] Condensed Income Statements, Captions [Line Items] Condensed Income Statements, Captions [Line Items] Revenue and Other Income: Revenues [Abstract] Miscellaneous Other Income Other Income Gain on Sale of Assets Total Revenue and Other Income Revenues Costs and Expenses: Costs and Expenses [Abstract] Operating and Other Costs Operating Costs and Expenses Freight Expense Freight Expense Freight Expense Selling, General and Administrative Costs Selling, General and Administrative Expense Interest Expense, net Interest Income (Expense), Net Total Costs and Expenses Costs and Expenses Income Tax (Benefit) Expense Income Tax Expense (Benefit) Net Income Less: Net Income Attributable to Noncontrolling Interest Net Income (Loss) Attributable to Noncontrolling Interest Net Income Attributable to CONSOL Energy Inc. Shareholders Net Income (Loss) Attributable to Parent Numerator: Earnings Per Share [Abstract] Denominator: Earnings Per Share, Diluted, Other Disclosures [Abstract] Weighted-average shares of common stock outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic Effect of dilutive shares (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Weighted-average diluted shares of common stock outstanding (in shares) Weighted Average Number of Shares Outstanding, Diluted Earnings per Share: Earnings Per Share, Basic and Diluted [Abstract] Basic (in dollars per share) Income (Loss) from Continuing Operations, Per Basic Share Dilutive (in dollars per share) Income (Loss) from Continuing Operations, Per Diluted Share Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statements, Captions [Line Items] Condensed Balance Sheet Statements, Captions [Line Items] Current Assets: Assets, Current [Abstract] Cash and Cash Equivalents Trade Accounts Receivable, Net, Current Other Receivables Other Receivables, Net, Current Inventories Prepaid Expenses and Other Assets Prepaid Expense and Other Assets, Current Total Current Assets Assets, Current Property, Plant and Equipment: Property, Plant and Equipment, Net [Abstract] Property, Plant and Equipment Less—Accumulated Depreciation, Depletion and Amortization Other Assets: Other Assets [Abstract] Deferred Income Taxes Deferred Income Tax Assets, Net Affiliated Credit Facility Restricted Cash and Cash Equivalents, Noncurrent Investment in Affiliates Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures Other Other Assets, Miscellaneous, Noncurrent Total Other Assets Other Assets, Noncurrent TOTAL ASSETS Assets Current Liabilities: Liabilities, Current [Abstract] Accounts Payable Accounts Payable, Current Accounts Payable (Recoverable)-Related Parties Current Portion of Long-Term Debt Long-term Debt and Capital Lease Obligations, Current Other Accrued Liabilities Accrued Liabilities, Current Total Current Liabilities Liabilities, Current Long-Term Debt Long-term Debt and Capital Lease Obligations Deferred Credits and Other Liabilities: Deferred Credits and Other Liabilities [Abstract] Postretirement Benefits Other Than Pensions Liability, Other Postretirement Defined Benefit Plan, Noncurrent Pneumoconiosis Benefits Employee Related Liabilities, Medical and Disability Benefits, Noncurrent Employee Related Liabilities, Medical and Disability Benefits, Noncurrent Asset Retirement Obligations Asset Retirement Obligations, Noncurrent Workers’ Compensation Workers' Compensation Liability, Noncurrent Salary Retirement Liability, Defined Benefit Pension Plan, Noncurrent Other Other Liabilities, Noncurrent Total Deferred Credits and Other Liabilities Liabilities, Other than Long-term Debt, Noncurrent Total CONSOL Energy Inc. Stockholders' Equity Stockholders' Equity Attributable to Parent Noncontrolling Interest Stockholders' Equity Attributable to Noncontrolling Interest TOTAL LIABILITIES AND EQUITY Liabilities and Equity MEDCO Revenue Bonds in Series due September 2025 at 5.75% MEDCO Revenue Bonds in Series due September 2025 at 5.75% [Member] MEDCO Revenue Bonds in Series due September 2025 at 5.75% [Member] Advance royalty commitments Advance Royalty Commitments [Member] Advance Royalty Commitments [Member] Long-term debt Long-term Debt Long term debt, carrying amount Long-term Debt, Gross Less: Unamortized Debt Issuance Costs Debt Issuance Costs, Net Less amounts due in one year Long-term Debt, Current Maturities Long-Term Debt Long-term Debt, Excluding Current Maturities Unamortized discount Unamortized Debt Issuance Expense Weighted average interest rate (as a percent) Debt, Weighted Average Interest Rate Current portion of capital lease obligations Capital Lease Obligations, Current Schedule of Industry Segment Results Schedule of Segment Reporting Information, by Segment [Table Text Block] Schedule of Segment Revenues from Major Customers Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block] Schedule of Total Assets Reconciliation of Assets from Segment to Consolidated [Table Text Block] Schedule of Related Party Transactions Schedule of Related Party Transactions [Table Text Block] MISCELLANEOUS OTHER INCOME Interest and Other Income [Text Block] Effective tax rate (as a percent) Effective Income Tax Rate Reconciliation, Percent Deferred tax expense Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Change In Tax Rate, Deferred Tax Asset Provisional Income Tax Expense (Benefit) Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Change In Tax Rate, Deferred Tax Asset Provisional Income Tax Expense (Benefit) Tax benefit Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount Schedule of Components of Net Periodic Benefit (Credit) Cost Schedule of Defined Benefit Plans Disclosures [Table Text Block] Document and Entity Information [Abstract] Document and Entity Information [Abstract] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Income Statement [Abstract] (Loss) Gain on Sale of Assets Loss on Debt Extinguishment Less: Net Income Attributable to Noncontrolling Interest Earnings per Share: Total Basic Earnings per Share Total Dilutive Earnings per Share Commitments and Contingencies Disclosure [Abstract] COMMITMENTS AND CONTINGENT LIABILITIES Commitments Contingencies and Guarantees [Text Block] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Retirement Plan Name [Axis] Retirement Plan Name [Axis] Retirement Plan Name [Domain] Retirement Plan Name [Domain] CWP Coal Workers Pneumoconiosis [Member] Coal Workers' Pneumoconiosis Workers' Compensation Workers Compensation [Member] Workers' Compensation Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Service Cost Defined Benefit Plan, Service Cost Interest Cost Defined Benefit Plan, Interest Cost Amortization of Actuarial Gain Defined Benefit Plan, Amortization of Gain (Loss) State Administrative Fees and Insurance Bond Premiums Post Employment Benefit Plan, State Administrative Fees and Insurance Bond Premiums Post Employment Benefit Plan, State Administrative Fees and Insurance Bond Premiums Net Periodic Benefit (Credit) Cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) FAIR VALUE OF FINANCIAL INSTRUMENTS Fair Value Disclosures [Text Block] PROPERTY, PLANT AND EQUIPMENT Property, Plant and Equipment Disclosure [Text Block] Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Current Assets: Accounts and Notes Receivable Accounts, Notes, Loans and Financing Receivable, Net, Current [Abstract] Property, Plant and Equipment: Other Assets: LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Current Liabilities: Long-Term Debt: Liabilities, Noncurrent [Abstract] Capital Lease Obligations Capital Lease Obligations, Noncurrent Total Long-Term Debt TOTAL LIABILITIES Liabilities Stockholders' Equity: Partners' Capital [Abstract] Common Stock, $0.01 Par Value; 62,500,000 Shares Authorized, 27,815,470 Issued and Outstanding at September 30, 2018; 27,973,281 Issued and Outstanding at December 31, 2017 Common Stock, Value, Issued Capital in Excess of Par Value Additional Paid in Capital Retained Earnings (Deficit) Retained Earnings (Accumulated Deficit) Accumulated Other Comprehensive Loss Accumulated Other Comprehensive Income (Loss), Net of Tax TOTAL EQUITY Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Carrying Amount Reported Value Measurement [Member] Fair Value Estimate of Fair Value Measurement [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Long-Term Debt, Carrying Amount Long-Term Debt, Fair Value Long-term Debt, Fair Value Schedule of Restricted Cash and Cash Equivalents Schedule of Cash and Cash Equivalents [Table Text Block] Schedule of Antidilutive Securities Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Schedule of Basic and Dilutive Earnings Per Share Schedule of Basic and Dilutive Earnings Per Share [Table Text Block] Schedule of Basic and Dilutive Earnings Per Share [Text Block] Schedule of Commitment Expiration Schedule of Guarantor Obligations [Table Text Block] Retained Earnings Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2018-02 Accounting Standards Update 2018-02 [Member] Accounting Standards Update 2018-02 [Member] ParentCo ParentCo [Member] ParentCo [Member] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Pennsylvania Mining Operations Pennsylvania Mining Operations [Member] Pennsylvania Mining Operations [Member] Cumulative effect adjustments Cumulative Effect of New Accounting Principle in Period of Adoption Ownership percentage Equity Method Investment, Ownership Percentage Common stock distributed in completion of separation agreement (in shares) Preferred stock, shares authorized Preferred Stock, Shares Authorized Preferred stock, shares issued Preferred Stock, Shares Issued Preferred stock, shares outstanding Preferred Stock, Shares Outstanding Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Pension Benefits Pension Plan [Member] Other Post-Employment Benefits Other Postretirement Benefits Plan [Member] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Expected Return on Plan Assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Amortization of Prior Service Credits Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Amortization of Actuarial Loss Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Anti-Dilutive Restricted Stock Units Restricted Stock Units (RSUs) [Member] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive securities excluded from calculation of earnings per share (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Subsequent Event [Table] Subsequent Event [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Subsequent Event [Line Items] Subsequent Event [Line Items] Cash distribution declared (per common unit) Distribution Made to Limited Partner, Distributions Declared, Per Unit Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Other Corporate and Other [Member] Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Segment Assets Capital Expenditures BASIS OF PRESENTATION Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block] OTHER ACCRUED LIABILITIES Accounts Payable and Accrued Liabilities Disclosure [Text Block] GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION Condensed Financial Information of Parent Company Only Disclosure [Text Block] Schedule of Guarantor Obligations [Table] Schedule of Guarantor Obligations [Table] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] Letters of Credit Standby Letters of Credit [Member] Surety Bonds Surety Bond [Member] Guarantees Other Guarantee Obligations [Member] Other Guarantee Obligations [Member] Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Employee-Related Employee-Related Commitment [Member] Employee-Related Commitment [Member] Environmental Environmental Commitment [Member] Environmental Commitment [Member] Other Other Commitment [Member] Other Commitment [Member] Guarantor Obligations [Line Items] Guarantor Obligations [Line Items] Total Amounts Committed Guarantor Obligations, Maximum Exposure, Undiscounted Less Than 1 Year Guarantor Obligations, Maximum Exposure, Undiscounted, Due in Next Twelve Months Guarantor Obligations, Maximum Exposure, Undiscounted, Due in Next Twelve Months 1-3 Years Guarantor Obligations, Maximum Exposure, Undiscounted, Due in Second and Third Year Guarantor Obligations, Maximum Exposure, Undiscounted, Due in Second and Third Year 3-5 Years Guarantor Obligations, Maximum Exposure, Undiscounted, Due in Fourth and Fifth Year Guarantor Obligations, Maximum Exposure, Undiscounted, Due in Fourth and Fifth Year Beyond 5 Years Guarantor Obligations, Maximum Exposure, Undiscounted, Due after Fifth Year Guarantor Obligations, Maximum Exposure, Undiscounted, Due after Fifth Year Retirement of common stock (in shares) Condensed Cash Flow Statement [Table] Condensed Cash Flow Statement [Table] Condensed Cash Flow Statements, Captions [Line Items] Condensed Cash Flow Statements, Captions [Line Items] Net Cash Provided by (Used in) Operating Activities Cash Flows from Investing Activities: (Investments in), net of Distributions from, Subsidiaries Payments for (Proceeds from) Businesses and Interest in Affiliates Cash Flows from Financing Activities: Payments on Capitalized Lease Obligations Affiliated Credit Facility Payments On Long Term Notes Including Redemption Premium Payments On Long Term Notes Including Redemption Premium Repayment of debt Distributions to Noncontrolling Interest Proceeds from (Payments to) Noncontrolling Interests Intercompany Contributions/(Distributions) Increase (Decrease) for Intercompany Transactions Increase (Decrease) for Intercompany Transactions Payments Of Distributions To Parent Debt-Related Financing Fees Payments of Debt Issuance Costs Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Operating and Other Costs Operating And Other Costs [Member] Operating And Other Costs [Member] Selling, General and Administrative Costs Selling, General and Administrative Expenses [Member] Majority Shareholder Majority Shareholder [Member] Total Services from CONSOL Energy Related Party Transaction, Expenses from Transactions with Related Party Common stock par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock shares authorized (in shares) Common Stock, Shares Authorized Common stock shares issued (in shares) Common Stock, Shares, Issued Common stock shares outstanding (in shares) Common Stock, Shares, Outstanding REVENUE Revenue from Contract with Customer [Text Block] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value Recurring Fair Value, Measurements, Recurring [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 1 Fair Value, Inputs, Level 1 [Member] Level 2 Fair Value, Inputs, Level 2 [Member] Level 3 Fair Value, Inputs, Level 3 [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Murray Energy Guarantees Guarantees, Fair Value Disclosure Disaggregation of Revenue by Major Source Disaggregation of Revenue [Table Text Block] Reconciliation of Assets from Segment to Consolidated [Table] Reconciliation of Assets from Segment to Consolidated [Table] Reportable Segments Reportable Segments [Member] Reportable Segments [Member] All Other Segments Other Segments [Member] Operating Segments Operating Segments [Member] Corporate Reconciling Items and Eliminations Corporate Reconciling Items And Eliminations [Member] Corporate Reconciling Items and Eliminations [Member] Segment Reporting, Asset Reconciling Item [Line Items] Segment Reporting, Asset Reconciling Item [Line Items] Items excluded from segment assets: Segment Reporting, Other Significant Reconciling Item, Consolidated [Abstract] Cash and other investments Investments and Cash Deferred tax assets Segment Assets SEGMENT INFORMATION Segment Reporting Disclosure [Text Block] Subsidence Liability Accrued Subsidence Liability, Current Accrued Subsidence Liability, Current Accrued Payroll and Benefits Accrued Payroll And Employee Benefits, Current Accrued Payroll And Employee Benefits, Current Accrued Interest Interest Payable, Current Litigation Estimated Litigation Liability, Current Accrued Other Taxes Accrual for Taxes Other than Income Taxes, Current Short-Term Incentive Compensation Accrued Bonuses, Current Deferred Revenue Contract with Customer, Liability, Current Longwall Equipment Buyout Gas Purchase Payable, Current Equipment Lease Rental Accrued Rent, Current Other Other Accrued Liabilities, Current Current Portion of Long-Term Liabilities: Long-Term Liabilities, Current [Abstract] Long-Term Liabilities, Current [Abstract] Postretirement Benefits Other than Pensions Liability, Other Postretirement Defined Benefit Plan, Current Liability, Other Postretirement Defined Benefit Plan, Current Asset Retirement Obligations Asset Retirement Obligation, Current Workers' Compensation Workers' Compensation Liability, Current Pneumoconiosis Benefits Employee Related Liabilities, Medical And Disability Benefits, Current Employee Related Liabilities, Medical And Disability Benefits, Current Total Other Accrued Liabilities Property, Plant and Equipment Property, Plant and Equipment [Table Text Block] INVENTORIES Inventory Disclosure [Text Block] Royalty Income - Non-Operated Coal Royalty Income Non-Operated Coal Royalty Income Non-Operated Coal Purchased Coal Sales Purchased Coal Sales Purchased Coal Sales Property Easements and Option Income Property Easements and Option Income Property Easements and Option Income Rental Income Rental Income, Nonoperating Interest Income Interest Income, Other Contract Buyout Gain (Loss) on Contract Termination Other Other Nonoperating Income Miscellaneous Other Income Loss Contingencies [Table] Loss Contingencies [Table] Litigation Case [Axis] Litigation Case [Axis] Litigation Case [Domain] Litigation Case [Domain] Fitzwater Litigation Fitzwater Litigation [Member] Fitzwater Litigation [Member] Casey Litigation Casey Litigation [Member] Casey Litigation [Member] Litigation Status [Axis] Litigation Status [Axis] Litigation Status [Domain] Litigation Status [Domain] Pending Litigation Pending Litigation [Member] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Number of plaintiffs Loss Contingency, Number of Plaintiffs Number of mines sold Number of Mines Sold Number of Mines Sold Guarantees maximum exposure Guarantees, Maximum Exposure Guarantees, Maximum Exposure Fair value of guarantees