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Identified intangible assets amortized, contract term Business Combination, Identified Intangible Assets Amortized, Contract Term Business Combination, Identified Intangible Assets Amortized, Contract Term Total Amounts Committed Guarantor Obligations, Maximum Exposure, Undiscounted Line of Credit Line of Credit [Member] Restatement Determination Date Restatement Determination Date Expected Return on Plan Assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Pneumoconiosis Benefits Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Pneumoconiosis Benefits Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Pneumoconiosis Benefits Long-Term Debt Net of Debt Issuance Costs Long-Term Debt and Lease Obligation, Including Current Maturities Derivative Instrument [Axis] Derivative Instrument [Axis] Beginning balance Ending balance Accounts Receivable, Allowance for Credit Loss Proceeds from Sales of Assets Proceeds from Sale of Productive Assets Amendment Flag Amendment Flag Consolidated Entities [Axis] Consolidated Entities [Axis] Current Liabilities: Liabilities, Current [Abstract] Common stock, average price (in dollars per share) Shares Acquired, Average Cost Per Share Provision for Expected Credit Losses Accounts Receivable, Credit Loss Expense (Reversal) Gross contractual amount of receivables Business Combination, Acquired Receivable, Purchased without Credit Deterioration, Gross Contractual Amount Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Payments on Finance Lease Obligations Finance Lease, Principal Payments Leer South Mine Leer South Mine [Member] Leer South Mine Gross Unrealized Losses Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax Letters of Credit: Standby Letters of Credit [Member] Property, Plant and Equipment, net Business Combination, Recognized Asset Acquired, Property, Plant, and Equipment Gross assets under finance leases Finance Lease, Right-of-Use Asset, before Accumulated Amortization Schedule Available-for-Sale Securities Debt Securities, Available-for-Sale [Table Text Block] Loss Contingencies [Table] Loss Contingencies [Table] Long-Term Debt Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Long-term Debt Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Long-term Debt Payments of Excise Tax on Share Repurchases Payments of Excise Tax on Share Repurchases Payments of Excise Tax on Share Repurchases Total Long-Term Liabilities Liabilities, Noncurrent Merger with Arch Stock Issued During Period, Value, Acquisitions Consolidated Entities [Domain] Consolidated Entities [Domain] Business Combination, Pro Forma Information, Nonrecurring Adjustment [Axis] Business Combination, Pro Forma Information, Nonrecurring Adjustment [Axis] Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Schedule of Cash and Cash Equivalents Schedule of Cash and Cash Equivalents [Table Text Block] Property, Plant, and Equipment [Abstract] Entity Address, State or Province Entity Address, State or Province PEO Total Compensation Amount PEO Total Compensation Amount Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Capital Expenditures Segment Reporting, Long-Lived Asset, Expenditure for Addition Cash and Cash Equivalents [Abstract] Components of Coal Workers' Pneumoconiosis (CWP) and Workers' Compensation Net Periodic Benefit Costs Pneumoconiosis Benefits And Workers Compensation Disclosure [Text Block] Represents disclosure of pneumoconiosis benefits and workers compensation. Long-Term Liabilities: Liabilities, Noncurrent [Abstract] Weighted-Average Shares of Common Stock Outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic Price Risk Derivative Price Risk Derivative [Member] Retirement Benefits [Abstract] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Loss Contingencies [Line Items] Loss Contingencies [Line Items] Number of reportable segments Number of Reportable Segments Total Current Liabilities Liabilities, Current Excise Tax on Repurchases of Common Stock Stock Repurchased During Period, Excise Taxes Stock Repurchased During Period, Excise Taxes Nonrecurring Adjustment, Inventory Fair Value Adjustment Business Combination, Pro Forma Information, Nonrecurring Adjustment, Inventory, Fair Value Adjustment [Member] Short-Term Debt, Type [Domain] Short-Term Debt, Type [Domain] Amortized Cost Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss Entity Address, City or Town Entity Address, City or Town Pending Litigation Pending Litigation [Member] Receivables [Abstract] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Expected amortization rate in 2029 Finite-Lived Intangible Asset, Expected Amortization Rate, Year Three Finite-Lived Intangible Asset, Expected Amortization Rate, Year Three Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Aggregate notional volume (in gallons) Derivative, Nonmonetary Notional Amount Debt Securities, Held-to-Maturity [Table] Debt Securities, Held-to-Maturity [Table] Level 2 Fair Value, Inputs, Level 2 [Member] Receivable [Domain] Receivable [Domain] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Arch Resources, Inc Arch Resources, Inc [Member] Arch Resources, Inc Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Other Comprehensive Income Other Comprehensive Income (Loss), Net of Tax Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Schedule of Long-Term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] PRB PRB [Member] PRB Earnings (Loss) per Share Earnings Per Share, Policy [Policy Text Block] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Litigation Case [Axis] Litigation Case [Axis] Equipment Financing Capital Expenditures Incurred but Not yet Paid Schedule of Segment Reporting Information by Segment Segment Reporting [Table Text Block] Defined Contribution Plan Disclosure [Line Items] Defined Contribution Plan Disclosure [Line Items] Actuarially Determined Long-Term Liability Adjustments, Tax Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax Schedule of Other Accrued Liabilities Schedule of Accrued Liabilities [Table Text Block] Repayments of lines of credit Repayments of Lines of Credit Reconciliation of Segment Profit or Loss Measure to Consolidated Earnings (Loss) Before Income Tax: Segment Reporting, Reconciliation [Abstract] Intangible assets acquired Business Combination, Recognized Asset Acquired, Identifiable Intangible Asset, Excluding Goodwill Property, Plant and Equipment Property, Plant, and Equipment [Text Block] Document Period End Date Document Period End Date Changes in Operating Assets: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Net Cash (Used in) Provided by Investing Activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Preferred stock, shares outstanding (in shares) Preferred Stock, Shares Outstanding Debt instrument, face amount Debt Instrument, Face Amount Stock Repurchases Equity [Text Block] Costs and Expenses: Costs and Expenses [Abstract] Security Exchange Name Security Exchange Name Debt instrument, term Debt Instrument, Term Debt instrument, covenant, fixed charge coverage ratio, minimum Debt Instrument Covenant Fixed Charge Coverage Ratio Minimum Represents information related to minimum fixed coverage ratio for debt instrument covenant. Asset Retirement Obligations Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Asset Retirement Obligations Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Asset Retirement Obligations Annual servicing costs Estimated Liability Annual Servicing Cost Estimated Liability Annual Servicing Cost Accumulated Other Comprehensive Loss Accumulated Other Comprehensive Income (Loss), Net of Tax Entity Shell Company Entity Shell Company Consolidation Items [Domain] Consolidation Items [Domain] Closed and Idle Mine Costs Closed and Idle Mine Costs Closed and Idle Mine Costs Schedule of Allowance for Credit Losses Accounts Receivable, Allowance for Credit Loss [Table Text Block] Schedule of Property, Plant and Equipment Property, Plant, and Equipment [Table Text Block] Statement of Comprehensive Income [Abstract] Other Debt Arrangements Other Asset Backed Financing [Member] Represents information related to other asset backed financing. Name Outstanding Recovery, Individual Name Earnings (Loss) per Share: Earnings Per Share [Abstract] Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Document Fiscal Period Focus Document Fiscal Period Focus Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Accounts and Notes Receivable Increase (Decrease) in Accounts and Notes Receivable Total Liabilities Liabilities Trading Symbol Trading Symbol Fair Value Available-for-sale debt securities Debt Securities, Available-for-Sale, Excluding Accrued Interest Geographical [Domain] Geographical [Domain] Capital Expenditures Payments to Acquire Property, Plant, and Equipment Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Series 2020 Series 2020 [Member] Series 2020 Accounts and Notes Receivable: Accounts and Financing Receivable, after Allowance for Credit Loss [Abstract] Airshafts Airshafts [Member] Represents information related to airshafts. Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Financing Receivable, Allowance for Credit Loss [Line Items] Financing Receivable, Allowance for Credit Loss [Line Items] Schedule of Allocation of Aggregate Purchase Price Business Combination, Recognized Asset Acquired and Liability Assumed [Table Text Block] Company Selected Measure Name Company Selected Measure Name Schedule of Restricted Cash Restrictions on Cash and Cash Equivalents [Table Text Block] Income Tax Disclosure [Abstract] Non-Service Related Pension and Postretirement Benefit Costs Pension and Other Postretirement Benefits Cost (Reversal of Cost) Coal Coal [Member] Unrealized Gain on Investments in Available-for-Sale Securities (Net of Tax: ($339), ($119), ($293), ($47)) Investments in Available-for-Sale Securities OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment and Tax Non-Cash Investing and Financing Activities: Noncash Investing and Financing Items [Abstract] Purchase of Arch Tax-Exempt Bonds Payments to Acquire Other Investments Other Accrued Liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Accrued Liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Accrued Liabilities Long-Term Debt, Gross Long-Term Debt, Gross Fee percentage Line of Credit Facility, Commitment Fee Percentage Credit Facility [Domain] Credit Facility [Domain] Depreciation, Depletion and Amortization Depreciation, Depletion and Amortization, Nonproduction Cash Flows from Operating Activities: Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Other Receivables, net Other Receivables, Net, Current Compensation Amount Outstanding Recovery Compensation Amount Individual: Individual [Axis] Weighted-Average Diluted Shares of Common Stock Outstanding (in shares) Weighted Average Number of Shares Outstanding, Diluted Business acquisition, percentage Business Combination, Voting Equity Interest Acquired, Percentage Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Entity Emerging Growth Company Entity Emerging Growth Company Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Net Assets Acquired Business Combination, Recognized Asset Acquired to Liability Assumed, Excess (Less) Credit Loss [Abstract] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Proceeds from lines of credit Proceeds from Lines of Credit Total Property, Plant and Equipment—Net Total Property, Plant and Equipment—Net Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization Derivatives Derivative Instruments and Hedging Activities Disclosure [Text Block] U.S. Treasury Securities US Treasury Securities [Member] Dividend Equivalents Earned on Stock-Based Compensation Awards Dividend, Share-Based Payment Arrangement Postretirement Benefits Other than Pensions Postretirement Benefits Other than Pensions Represents current liability for other postretirement defined benefit plan. WVEDA Solid Waste Disposal Facility Revenue Bonds at 5.45% WVEDA Solid Waste Disposal Revenue Bonds [Member] WVEDA Solid Waste Disposal Revenue Bonds Changes in Other Assets Increase (Decrease) in Other Noncurrent Assets Revenue from Contract with Customer [Abstract] Debt instrument, covenant, net leverage ratio, actual Debt Instrument Covenant Net Leverage Ratio Actual Represents actual net leverage ratio for debt instrument covenant. Less: Accumulated Depreciation, Depletion and Amortization Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, Accumulated Depreciation and Amortization Award Timing Predetermined Award Timing Predetermined [Flag] Restricted Cash—Current Restricted Cash, Current Debt instrument, covenant, first lien gross leverage ratio Debt Instrument Covenant First Lien Gross Leverage Ratio Represents first lien gross leverage ratio for debt instrument covenant. Letters of credit outstanding Letters of Credit Outstanding, Amount Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Employee Stock-Based Compensation APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Level 1 Fair Value, Inputs, Level 1 [Member] Equity Issued as Consideration for Merger Equity Issued as Consideration for Merger Equity Issued as Consideration for Merger Effective tax rate Effective Income Tax Rate Reconciliation, Percent Organization, Consolidation and Presentation of Financial Statements [Abstract] Litigation Status [Domain] Litigation Status [Domain] Effect of Dilutive Shares (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements All Executive Categories All Executive Categories [Member] Corporate and Other Corporate And Reconciling Items [Member] Corporate And Reconciling Items Repurchases of Common Stock Stock Repurchased and Retired During Period, Value Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Other Comprehensive Income: Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Long-Term Debt (Excluding Debt Issuance Costs) Long-Term Debt, Fair Value Schedule of Net Periodic Benefit Costs Schedule of Net Benefit Costs [Table Text Block] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Short-Term Investments Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Short-Term Investments Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Short-Term Investments Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Axis] Metallurgical Metallurgical [Member] Metallurgical Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Fair Value Disclosures [Abstract] Debt Disclosure [Abstract] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Current Portion of Long-Term Debt Less: Current Portion of Long-Term Debt Long-Term Debt and Lease Obligation, Current Segment Information Segment Reporting [Text Block] Borrowings outstanding Long-Term Line of Credit Industrial Industrial [Member] Industrial Minimum Minimum [Member] Payments on Other Debt Repayments of Other Debt Expiration Date Trading Arrangement Expiration Date Schedule of Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Payments on Asset Retirement Obligations Increase (Decrease) in Asset Retirement Obligations Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Workers' Compensation Workers Compensation [Member] Represents information related to workers compensation. Third-Party Terminal Revenue Terminal Revenue [Member] Represents information related to terminal revenue. Business Combination [Line Items] Business Combination [Line Items] Dividends on Common Shares Aggregate amount of dividends Dividends, Common Stock Net Periodic Benefit Cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Derivative [Table] Derivative [Table] Financing Receivable, Allowance for Credit Loss [Table] Financing Receivable, Allowance for Credit Loss [Table] Common stock, shares authorized (in shares) Common Stock, Shares Authorized Trade Receivables, net Business Combination, Recognized Asset Acquired, Receivable, Current Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Security, Excluded EPS Calculation [Table] Schedule of Held-to-Maturity Securities [Line Items] Schedule of Held-to-Maturity Securities [Line Items] Schedule of Carrying Values and Estimated Fair Values of Debt Instruments Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block] Exercise Price Award Exercise Price Cash Flows from Investing Activities: Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Litigation Status [Axis] Litigation Status [Axis] Aggregate amount Share Repurchase Program, Authorized, Amount Segment Reporting [Line Items] Segment Reporting [Line Items] Net Loss Business Combination, Pro Forma Information, Pro Forma Income (Loss), after Tax Document Quarterly Report Document Quarterly Report Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Segments [Domain] Segments [Domain] Trade receivables Accounts Receivable, after Allowance for Credit Loss Pneumoconiosis Benefits Employee Related Liabilities Medical And Disability Benefits, Current Represents current medical and disability for employee related liabilities. Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Business Combination [Table] Business Combination [Table] Equity Component [Domain] Equity Component [Domain] PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract] Investments in DTA Payments to Acquire Projects Costs and Expenses Costs and Expenses Adoption Date Trading Arrangement Adoption Date Finance Lease Obligations Weighted-Average Interest Rate Finance Lease, Weighted Average Discount Rate, Percent Stated Interest Rate Debt instrument, interest rate, stated percentage Debt Instrument, Interest Rate, Stated Percentage Export Export Coal Revenue [Member] Represents information related to export cocal revenue. Total Stockholders’ Equity Beginning balance Ending balance Equity, Attributable to Parent Other Noncurrent Assets, net Business Combination, Recognized Asset Acquired, Other Asset, Noncurrent Total Workers’ Compensation Expense Defined Benefit Plan, Workers Compensation Expense Defined Benefit Plan, Workers Compensation Expense Pension Benefits Assets for Plan Benefits, Defined Benefit Plan ASSETS Assets [Abstract] Title Trading Arrangement, Individual Title Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Other Liabilities Disclosure [Abstract] Workers' Compensation Workers' Compensation Liability, Current Current Portion of Long-Term Liabilities: Other Liabilities, Current [Abstract] Stock issued (in shares) Business Combination, Consideration Transferred, Equity Interest, Share Issued, Number of Shares Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Insider Trading Policies and Procedures [Line Items] Finance Lease Obligations Finance Lease, Liability Other Non-Trade Contractual Arrangements Other Non-trade Contractual Arrangements [Member] Represents other non-trade contractual arrangements. Other Accrued Liabilities Accounts Payable and Accrued Liabilities Disclosure [Text Block] Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Performance Share Units Performance Shares [Member] Deferred Income Taxes Deferred Income Tax Expense (Benefit) Business Combination [Domain] Business Combination [Domain] Debt instrument, covenant, net leverage ratio, maximum Debt Instrument Covenant Net Leverage Ratio Maximum Represents maximum net leverage ratio for debt instrument covenant. Commitments and Contingent Liabilities Commitments and Contingencies Disclosure [Text Block] Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Antidilutive securities excluded from computation of earnings per share, amount (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Proceeds from Sales of Short-Term Investments Proceeds from Sale of Short-Term Investments Restricted Stock Units (RSUs) Restricted Stock Units (RSUs) [Member] Schedule of Antidilutive Securities Excluded from Computation of Earnings (Loss) per Share Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Entity Central Index Key Entity Central Index Key Non-Guarantor Subsidiaries Non-Guarantor Subsidiaries [Member] All Adjustments to Compensation All Adjustments to Compensation [Member] Business Combination [Axis] Business Combination [Axis] Equity [Abstract] Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Net Cash Provided by Operating Activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Water Treatment Trust Funds Water Treatment Trust Funds [Member] Water Treatment Trust Funds Outstanding performance obligation, percentage Revenue, Remaining Performance Obligation, Percentage Stockholders' Equity: Equity, Attributable to Parent [Abstract] Income Statement [Abstract] Income Statement [Abstract] Document Transition Report Document Transition Report Expected amortization rate in 2026 Finite-Lived Intangible Asset, Expected Amortization Rate, Remainder of Fiscal Year Finite-Lived Intangible Asset, Expected Amortization Rate, Remainder of Fiscal Year Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Intersegment Revenues Intersegment Eliminations [Member] Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Margin percentage Reduced annual rate Debt Instrument, Basis Spread on Variable Rate Other Current Assets Business Combination, Recognized Asset Acquired, Other Asset, Current City Area Code City Area Code Total Property, Plant and Equipment Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, before Accumulated Depreciation and Amortization Accumulated Other Comprehensive (Loss) Income AOCI Attributable to Parent [Member] All Individuals All Individuals [Member] Subsequent Events Subsequent Events [Text Block] Dividends and Dividend Equivalents Paid Payments of Dividends Pension Benefits Liability, Defined Benefit Pension Plan, Noncurrent Name Forgone Recovery, Individual Name Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Equity portion of purchase consideration Total Equity Portion of Purchase Price Consideration Business Combination, Consideration Transferred, Equity Interest Basis of Presentation [Table] Basis of Presentation [Table] Basis of Presentation Statement [Line Items] Statement [Line Items] Total Assets Segment assets Segment Assets Assets High CV Thermal High CV Thermal [Member] Represents information related to Pennsylvania Mining Complex. Workers’ Compensation Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Worker's Compensation Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Worker's Compensation Coal Properties and Surface Lands Mining Properties and Mineral Rights [Member] Preferred stock, shares issued (in shares) Preferred Stock, Shares Issued Environmental Environmental Commitment [Member] Represents information related to environmental commitment. Amortization of Prior Service Credits Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Operating Segments Operating Segments [Member] Accumulated amortization for finance leases Finance Lease, Right-of-Use Asset, Accumulated Amortization Interest Expense Interest Expense, Nonoperating Pro forma expense adjustments (before tax) Business Combination, Pro Forma Information, Pro Forma Income (Loss), Before Tax Business Combination, Pro Forma Information, Pro Forma Income (Loss), Before Tax Gross Unrealized Gains Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax Total Liabilities Assumed Business Combination, Recognized Liability Assumed, Liability Metallurgical Metallurgical Segment [Member] Represents CONSOL Marine Terminal. PEO PEO [Member] Accrued Other Taxes Accrual for Taxes Other than Income Taxes, Current Credit Losses Credit Loss, Financial Instrument [Text Block] Measurement Basis [Axis] Measurement Basis [Axis] Repurchases of Common Stock (in shares) Repurchased and retired (in shares) Stock Repurchased and Retired During Period, Shares Other Noncurrent Liabilities Other Liabilities, Noncurrent Retirement Plan Type [Axis] Retirement Plan Type [Axis] Inventories Business Combination, Recognized Asset Acquired, Inventory, Current Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Accounts Payable Business Combination, Recognized Liability Assumed, Accounts Payable, Current Equipment Financing (6.84% and 7.55% Weighted-Average Interest Rates) Equipment Financing [Member] Equipment Financing Subsequent Event Type [Domain] Subsequent Event Type [Domain] Amortized over a weighted average remaining contract term Business Combination, Amortized Over Weighted Average Remaining Contract Term Business Combination, Amortized Over Weighted Average Remaining Contract Term Retained Earnings Retained Earnings [Member] Revolving Credit Facility Revolving Credit Facility [Member] Cash and Cash Equivalents Business Combination, Recognized Asset Acquired, Cash and Cash Equivalent Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Business Interruption Loss [Domain] Business Interruption Loss [Domain] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Award Timing Disclosures [Line Items] Diluted Earnings (Loss) per Share (in dollars per share) Diluted (in dollars per share) Earnings Per Share, Diluted Entity Current Reporting Status Entity Current Reporting Status Net Cash Used in Financing Activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Total Shareholder Return Amount Total Shareholder Return Amount Shares Withheld for Taxes Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation United Mine Workers of America 1992 Benefit Plan Litigation United Mine Workers of America 1992 Benefit Plan Litigation [Member] Represents united mine workers of America 1992 benefit plan litigation. Litigation Case [Domain] Litigation Case [Domain] Other Revenue Other Revenue [Member] Other Revenue Amortization expenses Intangible Asset, Finite-Lived, Amortization Expense Dominion Terminal Dominion Terminal [Member] Dominion Terminal Less Than 1 Year Guarantor Obligations Maximum Exposure Undiscounted Due In Next Twelve Months Represents undiscounted maximum exposure for guarantor obligation due in next twelve months. Schedule of Pro Forma Adjustments Business Combination, Pro Forma Information [Table Text Block] Adjustments to Reconcile Net Income (Loss) to Net Cash Provided by Operating Activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Total Assets Acquired Business Combination, Recognized Asset Acquired, Asset Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Pension Benefits Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Pension Benefits Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Pension Benefits Business Combination, Pro Forma Information, Nonrecurring Adjustment [Domain] Business Combination, Pro Forma Information, Nonrecurring Adjustment [Domain] Cash Flows from Financing Activities: Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Revenues Total Revenue from Contracts with Customers Revenue from Contract with Customer, Excluding Assessed Tax Other Other Commitment [Member] Represents information related to other commitment. Unused borrowing capacity Line of Credit Facility, Remaining Borrowing Capacity Fee on unused commitments percentage Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Interest Cost Defined Benefit Plan, Interest Cost Financial Instruments [Domain] Financial Instruments [Domain] Surety Bonds: Surety Bond [Member] Commodity Derivatives Derivative Asset Inventories Inventory Disclosure [Text Block] Revolving Credit Facility and TLA Facility Revolving Credit Facility and TLA Facility [Member] Represents information related to revolving credit facility and TLA facility. Intangible Asset, Finite-Lived, Class [Axis] Intangible Asset, Finite-Lived, Class [Axis] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Underlying Securities Award Underlying Securities Amount Purchases of Short-Term Investments Payments to Acquire Short-Term Investments Fair Value Estimate of Fair Value Measurement [Member] Revenue from Contracts with Customers Revenue from Contract with Customer [Text Block] Issuance of Common Stock Stock Issued During Period, Value, New Issues Debt instrument, covenant, first lien gross leverage ratio, actual Debt Instrument Covenant First Lien Gross Leverage Ratio Actual Represents the actual first lien gross leverage ratio for debt instrument covenant. Other Operating Liabilities Increase (Decrease) in Other Current Liabilities Other Investing Activity Payment for (Proceeds from) Other Investing Activity Inventories Increase (Decrease) in Inventories Plant and Equipment Coal and Other Plant and Equipment [Member] Represents information related to coal and other plant and equipment. Postretirement Benefits Other Than Pensions Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Postretirement Benefits Other Than Pensions Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Postretirement Benefits Other Than Pensions Number of states operating with mining and terminal facilities Number Of States Operating With Mining And Terminal Facilities Number Of States Operating With Mining And Terminal Facilities Segment Reporting [Table] Segment Reporting [Table] Other Current Assets Other Assets, Current Commitments and Contingencies Disclosure [Abstract] All Trading Arrangements All Trading Arrangements [Member] Net gains on changes in fair value Derivative, Gain (Loss) on Derivative, Net Other Performance Measure, Amount Other Performance Measure, Amount Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Income (Loss) from Operations Operating Income (Loss) Outstanding performance obligation, amount Revenue, Remaining Performance Obligation, Amount Current Fiscal Year End Date Current Fiscal Year End Date Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Derivative [Line Items] Derivative [Line Items] Merger with Arch Business Combination [Text Block] Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Dividends Declared per Common Share (in dollars per share) Dividends on Common Shares (in dollars per share) Dividends announced (in dollars per share) Common Stock, Dividends, Per Share, Declared Entity File Number Entity File Number Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Service Cost Defined Benefit Plan, Service Cost Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Common stock, shares issued (in shares) Common Stock, Shares, Issued Measure: Measure [Axis] 1-3 Years Guarantor Obligations Maximum Exposure Undiscounted Due In Second And Third Year Represents undiscounted maximum exposure due in send and third year for guarantor obligations. Schedule of Guarantor Obligations Schedule of Guarantor Obligations [Table Text Block] Asset Retirement Obligations Asset Retirement Obligations, Noncurrent Cost of Sales (exclusive of items shown separately below) Cost of Goods and Service, Excluding Depreciation, Depletion, and Amortization Equity Components [Axis] Equity Components [Axis] Product and Service [Domain] Product and Service [Domain] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Entity Interactive Data Current Entity Interactive Data Current Core Marine Terminal Core Marine Terminal [Member] Core Marine Terminal Deferred Income Taxes Deferred Income Tax Liabilities, Net Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Entity Small Business Entity Small Business Comprehensive Income (Loss) Comprehensive Income (Loss), Net of Tax, Attributable to Parent Beyond 5 Years Guarantor Obligations Maximum Exposure Undiscounted Due After Fifth Year Represents undiscounted maximum exposure for guarantor obligations due after fifth year. Termination Date Trading Arrangement Termination Date Property, Plant, and Equipment [Line Items] Property, Plant, and Equipment [Line Items] Number of mines Business Combination, Number Of Mines Business Combination, Number Of Mines Subsequent Events [Abstract] Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Statutory income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Actuarially Determined Long-Term Liability Adjustments (Net of Tax: ($191), ($109), ($382), ($218)) Actuarially Determined Long-Term Liability Adjustments Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Total Other Assets Other Assets, Noncurrent Document Type Document Type 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] Net fair value of derivatives included in Other Current Assets Derivative Asset, Current Other Accrued Liabilities Total Other Accrued Liabilities Accrued Liabilities, Current Loss on Debt Extinguishment Loss on Debt Extinguishment Loss on extinguishment of debt Gain (Loss) on Extinguishment of Debt Fair Value as of Grant Date Award Grant Date Fair Value Allowance for Credit Losses Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest Nonrecurring Adjustments Business Combination, Pro Forma Information, Nonrecurring Adjustment, Total [Member] Business Combination, Pro Forma Information, Nonrecurring Adjustment, Total Gain on Sale of Assets Gain (Loss) on Disposition of Assets Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Arrangement Duration Trading Arrangement Duration Subsequent Event [Line Items] Subsequent Event [Line Items] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Proceeds from Long-Term Debt Issuance Proceeds from Issuance of Long-Term Debt Local Phone Number Local Phone Number Other Postretirement Benefits Other Postretirement Benefits Plan [Member] Consolidation Items [Axis] Consolidation Items [Axis] Period for outstanding amounts prior to stated maturity Line Of Credit Facility, Outstanding Balance, Period Prior To Stated Maturity Line Of Credit Facility, Outstanding Balance, Period Prior To Stated Maturity Entity Address, Postal Zip Code Entity Address, Postal Zip Code Entity Registrant Name Entity Registrant Name Advance Royalty Commitments (8.04% Weighted-Average Interest Rates) Advance Royalty Commitments [Member] Represents information related to advance royalty commitments. Earnings (Loss) Before Income Tax Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Commitments and Contingent Liabilities (Note 14) Commitments and Contingencies Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Loss from Equity Method Investments Income (Loss) from Equity Method Investments Other Assets: Other Assets [Abstract] Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Pneumoconiosis Benefits Pneumoconiosis Benefits Represents noncurrent medical and disability benefits for employee related liabilities. Executive Category: Executive Category [Axis] Transportation Costs Transportation Expense Transportation Expense Amortization expense for assets under finance lease Finance Lease, Right-of-Use Asset, Amortization Receivable Type [Axis] Receivable Type [Axis] Accounts Receivable Securitization Accounts Receivable Securitization [Text Block] Entire disclosure of accounts receivable securitization. Changes in Operating Liabilities: Increase (Decrease) in Operating Liabilities [Abstract] Supplies Inventory, Supplies, Net of Reserves Number of export terminals with ownership interest Number Of Export Terminals, Ownership Interests Number Of Export Terminals, Ownership Interests LIABILITIES AND STOCKHOLDERS’ EQUITY Liabilities and Equity [Abstract] Intangible Asset, Finite-Lived, Class [Domain] Intangible Asset, Finite-Lived, Class [Domain] Funds for Asset Retirement Obligations Funds For Asset Retirement Obligations Funds For Asset Retirement Obligations Inventories Total Inventories Inventory, Net All Award Types Award Type [Domain] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Fair Value of Financial Instruments Fair Value Disclosures [Text Block] Level 3 Fair Value, Inputs, Level 3 [Member] Mine Development Mine Development [Member] Workers’ Compensation Workers' Compensation Liability, Noncurrent Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] PEO Name PEO Name Series 2021 Series 2021 [Member] Series 2021 Geographical [Axis] Geographical [Axis] Debt instrument, covenant, fixed charge coverage ratio, actual Debt Instrument Covenant Fixed Charge Coverage Ratio Actual Represents actual fixed charge coverage ratio for debt instrument covenant. Other Segment Items Segment Reporting, Other Segment Item, Amount Long-Lived Asset, Class [Axis] Long-Lived Asset, Class [Axis] Retirement Plan Name [Domain] Retirement Plan Name [Domain] Net Cash and Restricted Cash Acquired from Merger Cash Acquired from Acquisition Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Entity Tax Identification Number Entity Tax Identification Number Accounts Receivable, Allowance for Credit Loss [Roll Forward] Accounts Receivable, Allowance for Credit Loss [Roll Forward] Assets Acquired: Business Combination, Recognized Asset Acquired, Asset [Abstract] State Administrative Fees and Insurance Bond Premiums State Administrative Fees and Insurance Bond Premiums State Administrative Fees and Insurance Bond Premiums Cash, Cash Equivalents and Restricted Cash at Beginning of Period Cash, Cash Equivalents and Restricted Cash at End of Period Cash, Cash Equivalents and Restricted Cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Accounts Payable Increase (Decrease) in Accounts Payable Other Other Accrued Liabilities, Current Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Business Interruption Loss [Axis] Business Interruption Loss [Axis] Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Non-NEOs Non-NEOs [Member] Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Debt Instrument [Axis] Debt Instrument [Axis] Subsequent Event [Table] Subsequent Event [Table] Other Noncurrent Liabilities Business Combination, Recognized Liability Assumed, Other Liability, Noncurrent Purchase price consideration Payments to Acquire Businesses, Gross Stock-Based Compensation Share-Based Payment Arrangement, Noncash Expense Adjusted EBITDA Adjusted EBITDA Represents adjusted earnings before interest, taxes, depreciation, and amortization. Schedule of Inventories Schedule of Inventory, Current [Table Text Block] Long-Term Debt, Type [Domain] Long-Term Debt, Type [Domain] Basic Earnings (Loss) per Share (in dollars per share) Basic (in dollars per share) Earnings Per Share, Basic Repurchases of Common Stock Payments for Repurchase of Common Stock Total Current Assets Assets, Current Statistical Measurement [Axis] Statistical Measurement [Axis] Insider Trading Arrangements [Line Items] Award Type Award Type [Axis] Debt-Related Financing Fees Payments of Financing Costs Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Insured Workers’ Compensation Fees and Assessments Defined Benefit Plan, Workers Compensation Expense Insured Portion Defined Benefit Plan, Workers Compensation Expense Insured Portion Trade Receivables, net Accounts Receivable, after Allowance for Credit Loss, Current Retained Earnings Retained Earnings (Accumulated Deficit) Product and Service [Axis] Product and Service [Axis] Restricted Cash—Noncurrent Restricted Cash, Noncurrent Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Employee-Related Employee Related Commitment [Member] Represents information related to employee related commitment. Pension Benefits Pension Plan [Member] Common Stock Common Stock [Member] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Current Portion of Long-Term Debt Business Combination, Recognized Liability Assumed, Long-Term Debt, Current Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block] Cover [Abstract] Cover [Abstract] Other Receivables, net Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other Receivables, Net Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other Receivables, Net Reclassifications Reclassification, Comparability Adjustment [Policy Text Block] Basis of Presentation [Line Items] Basis of Presentation [Line Items] Basis of Presentation Derivative Contract [Domain] Derivative Contract [Domain] Equity Awards Adjustments Equity Awards Adjustments [Member] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Total Liabilities and Stockholders’ Equity Liabilities and Equity Nonrecurring Adjustment, Merger-Related Costs Business Combination, Pro Forma Information, Nonrecurring Adjustment, Acquisition-Related Cost [Member] Employee Stock Option Share-Based Payment Arrangement, Option [Member] Asset Retirement Obligations Asset Retirement Obligation, Current Segments [Axis] Segments [Axis] Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Inventory Disclosure [Abstract] Tabular List, Table Tabular List [Table Text Block] Capital in Excess of Par Value Additional Paid in Capital Changes in Other Liabilities Increase (Decrease) in Other Noncurrent Liabilities Other Costs Other Nonoperating Income (Expense) Long-Term Debt Long-Term Debt [Text Block] MEDCO Port Facilities Refunding Revenue Bonds at 5.00% MEDCO Revenue Bonds [Member] Represents information related to MEDCO revenue bonds in series due September 2025 at 5.75%. Other Operating Income and Expense, net Other Operating Income (Expense), Net Name Awards Close in Time to MNPI Disclosures, Individual Name Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Subsidence Liability Subsidence Liability, Current Represents current accrued subsidence liability. General and Administrative Costs General and Administrative Costs General and Administrative Expense Long-Lived Asset, Class [Domain] Long-Lived Asset, Class [Domain] Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Additional Information Segment Reporting, Other Disclosure [Abstract] Property, Plant, and Equipment [Table] Property, Plant, and Equipment [Table] Adjustment to Compensation: Adjustment to Compensation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Expected amortization rate in 2028 Finite-Lived Intangible Asset, Expected Amortization Rate , Year Two Finite-Lived Intangible Asset, Expected Amortization Rate , Year Two Hedging Designation [Axis] Hedging Designation [Axis] Francis Scott Key Bridge Collapse Francis Scott Key Bridge Collapse [Member] Francis Scott Key Bridge Collapse Trade Receivables Trade Accounts Receivable [Member] Credit Facility [Axis] Credit Facility [Axis] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Other Profit or Loss Reconciliation Of Segment Information, Other Profit (Loss) Reconciliation Of Segment Information, Other Profit (Loss) Advance Mining Royalties Coal Advance Mining Royalties [Member] Represents information related to Coal advance mining royalties. Long-Term Debt Long-Term Debt and Lease Obligation Name Measure Name Income Taxes Income Tax Disclosure [Text Block] Accounts Payable Accounts Payable, Current Pay vs Performance Disclosure [Line Items] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Other Adjustments to Net Income (Loss) Other Noncash Income (Expense) Debt Instrument [Line Items] Debt Instrument [Line Items] Other Current Assets Increase (Decrease) in Other Current Assets Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Expected amortization rate in 2027 Finite-Lived Intangible Asset, Expected Amortization Rate, Year One Finite-Lived Intangible Asset, Expected Amortization Rate, Year One Total Consideration Transferred Business Combination, Consideration Transferred Retirement Plan Type [Domain] Retirement Plan Type [Domain] Capital in Excess of Par Value Additional Paid-in Capital [Member] Entity Filer Category Entity Filer Category Defined Contribution Plan [Table] Defined Contribution Plan [Table] Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] Name Trading Arrangement, Individual Name Cash and Cash Equivalents Cash and Cash Equivalent Coal Inventory, Raw Materials, Net of Reserves Compensation Related Costs [Abstract] Company Selected Measure Amount Company Selected Measure Amount Not Designated as Hedging Instrument Not Designated as Hedging Instrument [Member] Funds for Asset Retirement Obligations Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Funds For Asset Retirement Obligations Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Funds For Asset Retirement Obligations Depreciation, Depletion and Amortization Depreciation, Depletion and Amortization Depreciation, Depletion and Amortization Entity Address, Address Line Two Entity Address, Address Line Two Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Accounts and Financing Receivables [Table] Retirement Plan Name [Axis] Retirement Plan Name [Axis] Current Assets: Assets, Current [Abstract] Insurance recoveries Insurance Recoveries Revenues Business Combination, Pro Forma Information, Pro Forma Revenue Non-PEO NEO Non-PEO NEO [Member] Power Generation Power Generation [Member] Power Generation Entity Address, Address Line One Entity Address, Address Line One CWP Coal Workers Pneumoconiosis [Member] Represents information related to coal workers pneumoconiosis. Amount outstanding Line of Credit Facility, Fair Value of Amount Outstanding Income Tax Expense Income tax expense Income Tax Expense (Benefit) PEDFA Solid Waste Disposal Facility Revenue Bonds at 5.45% PEDFA Solid Waste Disposal Revenue Bonds [Member] Represents information related to PEDFA solid waste disposal revenue bonds. Award Timing Method Award Timing Method [Text Block] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Basis of Consolidation Consolidation, Policy [Policy Text Block] Net Increase in Cash, Cash Equivalents and Restricted Cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Deferred Income Taxes Business Combination, Recognized Liability Assumed, Deferred Tax Liability Recognized Net Actuarial Loss (Gain) Defined Benefit Plan, Amortization of Gain (Loss) Net Income (Loss) Net Income (Loss) Net Income (Loss) Net income attributable to the SPVs Net Income (Loss) Attributable to Parent Long-Term Debt, Type [Axis] Long-Term Debt, Type [Axis] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Less: Unamortized Debt Issuance Costs Unamortized Debt Issuance Expense Statement [Table] Statement [Table] Liquidity requirement Line Of Credit Facility, Liquidity Requirement Linee Of Credit Facility, Liquidity Requirement, Minimum Domestic Domestic Coal Revenue [Member] Represents information related to domestic coal revenue. Accounts receivable eligible for securitization Accounts Receivable Eligible For Securitization Represents information related to accounts receivable eligible for securitization. Above Market Leases Above Market Leases [Member] Restatement Determination Date: Restatement Determination Date [Axis] Liability for below market lease acquired Business Combination, Recognized Liability Assumed, Below Market Lease, Gross, Noncurrent Business Combination, Recognized Liability Assumed, Below Market Lease, Gross, Noncurrent Interest Income Investment Income, Interest Liabilities Assumed: Business Combination, Recognized Liability Assumed, Liability [Abstract] Other Operating Income and Expense, net Other Operating Income (Expense), Net, Adjusted Other Operating Income (Expense), Net, Adjusted Property, plant and equipment Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment Damages value Loss Contingency, Damages Sought, Value Cash Costs of Revenue Cash Costs Of Revenue Cash Costs Of Revenue Postretirement Benefits Other Than Pensions Liability, Other Postretirement Defined Benefit Plan, Noncurrent Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Numerator: Net Income (Loss) Available to Common Stockholders, Diluted [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract]