75000 - Document - Cover link:presentationLink link:calculationLink link:definitionLink 75010 - Statement - CONDENSED STATEMENTS OF OPERATIONS link:presentationLink link:calculationLink link:definitionLink 75020 - Statement - CONDENSED BALANCE SHEETS link:presentationLink link:calculationLink link:definitionLink 75030 - Statement - CONDENSED BALANCE SHEETS (Parenthetical) link:presentationLink link:calculationLink link:definitionLink 75040 - Statement - CONDENSED STATEMENTS OF CASH FLOWS link:presentationLink link:calculationLink link:definitionLink 75050 - Statement - CONDENSED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY link:presentationLink link:calculationLink link:definitionLink 995455 - Disclosure - Business and Basis of Presentation link:presentationLink link:calculationLink link:definitionLink 995465 - Disclosure - Summary of Significant Accounting Policies link:presentationLink link:calculationLink link:definitionLink 995475 - Disclosure - Inventories, net link:presentationLink link:calculationLink link:definitionLink 995485 - Disclosure - Income Taxes link:presentationLink link:calculationLink link:definitionLink 995495 - Disclosure - Debt link:presentationLink link:calculationLink link:definitionLink 995505 - Disclosure - Leases link:presentationLink link:calculationLink link:definitionLink 995515 - Disclosure - Net Income (Loss) per Share link:presentationLink link:calculationLink link:definitionLink 995525 - Disclosure - Commitments and Contingencies link:presentationLink link:calculationLink link:definitionLink 995535 - Disclosure - Stockholders' Equity link:presentationLink link:calculationLink link:definitionLink 995545 - Disclosure - Derivative Instruments link:presentationLink link:calculationLink link:definitionLink 995555 - Disclosure - Fair Value of Financial Instruments link:presentationLink link:calculationLink link:definitionLink 995565 - Disclosure - Segment Information link:presentationLink link:calculationLink link:definitionLink 995575 - Disclosure - Summary of Significant Accounting Policies (Policies) link:presentationLink link:calculationLink link:definitionLink 995585 - 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Disclosure - Income Taxes (Details) link:presentationLink link:calculationLink link:definitionLink 995685 - Disclosure - Debt - Schedule of Long-Term Debt Instruments (Details) link:presentationLink link:calculationLink link:definitionLink 995695 - Disclosure - Debt - Schedule of Long-Term Debt Instruments (Details) link:presentationLink link:calculationLink link:definitionLink 995705 - Disclosure - Debt - Schedule of Long-Term Debt Instruments (Parenthetical) (Details) link:presentationLink link:calculationLink link:definitionLink 995715 - Disclosure - Debt - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 995725 - Disclosure - Leases - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 995735 - Disclosure - Leases - Schedule of Supplemental Balance Sheet Information (Details) link:presentationLink link:calculationLink link:definitionLink 995745 - Disclosure - Leases - Schedule of Supplemental Balance Sheet Information (Parenthetical) (Details) link:presentationLink link:calculationLink link:definitionLink 995755 - Disclosure - Leases - Schedule of Components of Lease Expense (Details) link:presentationLink link:calculationLink link:definitionLink 995765 - Disclosure - Leases - Schedule of Maturities of Lease Liabilities (Details) link:presentationLink link:calculationLink link:definitionLink 995775 - Disclosure - Leases - Schedule of Maturities of Lease Liabilities (Details) link:presentationLink link:calculationLink link:definitionLink 995785 - Disclosure - Leases - Schedule of Maturities of Lease Liabilities (Parenthetical) (Details) link:presentationLink link:calculationLink link:definitionLink 995795 - Disclosure - Leases - Schedule of Supplemental Cash Flow Information Related to Leases (Details) link:presentationLink link:calculationLink link:definitionLink 995805 - Disclosure - Net Income (Loss) per Share - Schedule of Earnings Per Share, Basic and Diluted (Details) link:presentationLink link:calculationLink link:definitionLink 995815 - Disclosure - Commitments and Contingencies (Details) link:presentationLink link:calculationLink link:definitionLink 995825 - Disclosure - Stockholders' Equity - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 995835 - Disclosure - Stockholders' Equity - Schedule of Dividends on Common Shares (Details) link:presentationLink link:calculationLink link:definitionLink 995845 - Disclosure - Derivative Instruments (Details) link:presentationLink link:calculationLink link:definitionLink 995855 - Disclosure - Fair Value of Financial Instruments - Schedule of Fair Value, Liabilities Measured on Recurring Basis (Details) link:presentationLink link:calculationLink link:definitionLink 995865 - Disclosure - Fair Value of Financial Instruments (Details) link:presentationLink link:calculationLink link:definitionLink 995875 - Disclosure - Segment Information - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 995885 - Disclosure - Segment Information - Schedule of Reconciliations of Segment Information to Consolidated Amounts (Details) link:presentationLink link:calculationLink link:definitionLink 995895 - Disclosure - Segment Information - Schedule of Revenue by Major Customers (Details) link:presentationLink link:calculationLink link:definitionLink 995905 - Disclosure - Segment Information - Schedule of Reconciliation of Segment Adjusted EBITDA to Net Income (Loss) (Details) link:presentationLink link:calculationLink link:definitionLink Scenario [Axis] Scenario [Axis] Common Stock, Dividends, Per Share, Cash Paid Dividends per share: Preferred Stock, Shares Issued Preferred stock issued (in shares) Debt Disclosure [Text Block] Debt Share Repurchase Program, Authorized, Amount Authorized amount of stock to be repurchased, value Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss, Current Short-term investments Long-Term Line of Credit Aggregate principal amount drawn Aggregate principal amount drawn Debt Instrument, Basis Spread on Variable Rate Basis spread on variable rate (as a percent) Basis spread on variable rate (as a percent) Commodity Contract [Member] Commodity Contract Weighted Average Number of Shares Outstanding, Diluted Weighted average number of shares outstanding - diluted Weighted-average shares used to compute net income (loss) per share - diluted (in shares) Not Designated as Hedging Instrument [Member] Not Designated as Hedging Instrument APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Stock based compensation expense Minimum [Member] Minimum Lessee, Operating And Finance Leases, Supplemental Cash Flow Information, Non-Cash Items [Abstract] Lessee, Operating And Finance Leases, Supplemental Cash Flow Information, Non-Cash Items [Abstract] Non-cash right-of-use assets obtained in exchange for lease obligations: Letter of Credit [Member] Letter of Credit O 2026 Q1 Dividends O 2026 Q1 Dividends [Member] O 2026 Q1 Dividends. Preferred Stock, Shares Outstanding Preferred stock outstanding (in shares) Debt Instrument, maturity date, description Debt Instrument, Maturity Date, Description Finance Lease, Liability, to be Paid, Year Two 2027 Fair Value, Recurring [Member] Fair Value, Recurring Common Stock, Shares, Issued Common stock issued (in shares) Common stock shares issued (in shares) Segment Reporting [Line Items] Segment Reporting Information [Line Items] Debt Instrument, Face Amount Face amount of debt Income Tax Expense (Benefit) Income tax (benefit) expense Income tax (expense) benefit Income tax expense (benefit) Income tax (expense) benefit Effective Income Tax Rate Reconciliation, Tax Credit, Energy-Related, Amount Recognized benefit from the 45X Credit Energy [Domain] Energy [Domain] Operating Segments [Member] Operating Segments Line of Credit Facility, Maximum Borrowing Capacity Aggregate lender commitment Treasury Stock, Common, Value Treasury stock, at cost (2,221,841 shares as of June 30, 2026, and December 31, 2025) Subsequent Event Type [Domain] Subsequent Event Type [Domain] Segment Reporting, Long-Lived Asset, Expenditure for Addition Capital expenditures Cost of Goods and Services Sold Cost of sales (exclusive of items shown separately below) Senior Secured Notes Due 2024, Existing Notes [Member] Senior Secured Notes Due 2024, Existing Notes [Member] Senior Secured Notes Due 2024, Existing Notes Senior Secured Notes Due 2024, Existing Notes Schedule of Long-Term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Product and Service, Other [Member] Other revenues Other revenues Other revenues Income Statement [Abstract] Income Statement [Abstract] Lessee, Finance Leases [Text Block] Leases Debt Instrument, Unamortized Discount Debt discount Lease, Cost [Table Text Block] Schedule of Components of Lease Expense Earnings Per Share, Basic Net income per share - basic Net income (loss) per share - basic Document Period End Date Document Period End Date Document Information [Table] Document Information [Table] Finance Lease, Interest Expense Interest on lease liabilities Operating cash flows from finance leases Cost of Goods and Service, Excluding Depreciation, Depletion, and Amortization Cash cost of sales Debt Instrument [Line Items] Debt Instrument [Line Items] Kelli K. Gant [Member] Kelli K. Gant. Kelli K. Gant [Member] Common Stock, Shares Authorized Common stock authorized (in shares) Common stock shares authorized (in shares) Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Finance Lease, Right-of-Use Asset, after Accumulated Amortization Finance lease right-of-use assets, net Finance lease right-of-use assets, net Prepaid Expense and Other Assets, Current Prepaid expenses and other receivables Total prepaid expenses and other Dividends [Domain] Dividends [Domain] Debt Instrument, Interest Rate, Stated Percentage Stated interest rate (as a percent) Costs and Expenses Total costs and expenses Assets Assets Total assets Title of 12(b) Security Title of 12(b) Security Preferred Stock, Value, Issued Preferred stock, $0.01 par value per share (10,000,000 shares authorized; no shares issued and outstanding) No Trading Symbol Flag No Trading Symbol Flag Finance Lease, Liability, to be Paid, Year Three 2028 Variable Rate [Axis] Variable Rate [Axis] Product [Member] Sales Inventory, raw materials, purchased parts, supplies and other, net of reserve. Inventory, Raw Materials, Purchased Parts, Supplies And Other, Net Of Reserve Raw materials, parts, supplies and other, net Recorded Unconditional Purchase Obligation Throughput obligation Recorded Unconditional Purchase Obligation, Total Lease obligation Right-of-Use Asset Obtained in Exchange for Finance Lease Liability Finance leases Finance leases Finance Lease, Right-of-Use Asset, Accumulated Amortization Accumulated amortization Accumulated amortization Segment Reporting [Table Text Block] Schedule of Reconciliations of Segment Information to Consolidated Amounts O 2025 Q4 Dividends O 2025 Q4 Dividends [Member] O 2025 Q4 Dividends Lessee, Operating Leases [Text Block] Leases Equity, Attributable to Parent Balance, end of period Balance, beginning of period Total stockholders’ equity Treasury Stock, Common [Member] Treasury Stock Other Assets, Noncurrent Other long-term assets Total other long-term assets Customer B. Customer B [Member] Customer B Income Tax Disclosure [Text Block] Income Taxes O 2025 Q2 Dividends [Member] O 2025 q2 dividends. O 2025 Q2 Dividends Earnings Per Share [Text Block] Net Income (Loss) per Share Swap [Member] Swap Number of Reportable Segments Number of reportable segments Assets And Liabilities, Lessee Assets And Liabilities, Lessee [Table Text Block] Schedule of Supplemental Balance Sheet Information Basis of Accounting, Policy [Policy Text Block] Basis of Presentation Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss, Noncurrent Long-term investments Fair Value, Liabilities Measured on Recurring Basis [Table Text Block] Schedule of Fair Value, Liabilities Measured on Recurring Basis Long-Term Debt Total debt Credit Facility [Axis] Credit Facility [Axis] O 2024 Q3 Dividends [Member] O 2024 q3 dividends. O 2024 Q3 Dividends Finance Lease, Liability, Undiscounted Excess Amount Less: amount representing interest Less: amount representing interest Stock, Class of Stock [Table] Schedule of Stock by Class [Table] Interest Income (Expense), Nonoperating Interest (expense) income, net Repayments of Long-Term Debt Repayment of debt Retirements of debt Proceeds from equipment financing facility. Proceeds From Equipment Financing Facility Proceeds from equipment financing Contractual Obligation Contractual Obligation, Total Future payments required under signed lease agreements Revolving Credit Facility [Member] ABL Facility ABL Borrowings Statistical Measurement [Axis] Statistical Measurement [Axis] Entity Interactive Data Current Entity Interactive Data Current Common Stock, Value, Issued Common stock, $0.01 par value, (140,000,000 shares authorized as of June 30, 2026, and December 31, 2025; 55,023,805 issued and 52,801,964 outstanding as of June 30, 2026; 54,791,997 issued and 52,570,156 outstanding as of December 31, 2025) Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Schedule of Earnings Per Share, Basic and Diluted Royalty Expense Coal royalty expense Proceeds from Sale of Property, Plant, and Equipment Proceeds from Sale of Property, Plant, and Equipment, Total Proceeds from sale of property, plant and equipment Unrecorded Unconditional Purchase Obligation Future payments required under signed lease agreements that have not yet commenced Unrecorded Unconditional Purchase Obligation, Total Unrecorded Unconditional Purchase Obligation Balance Sheet Amount Liabilities Total liabilities Senior Notes [Member] Senior Secured Notes Senior Secured Notes Energy Related Inventory, Coal Coal Product and Service [Axis] Product and Service [Axis] Retained Earnings (Accumulated Deficit) Retained earnings Fair Value, Inputs, Level 3 [Member] Level 3 Increase (Decrease) in Accounts Payable Accounts payable Common Stock, Dividends, Per Share, Declared Dividend per share (in dollars per share) Dividend per share (in dollars per share) Revenues [Abstract] Revenues: Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Business and Basis of Presentation Increase (Decrease) in Operating Capital [Abstract] Changes in operating assets and liabilities: O 2025 Q1 Dividends [Member] O 2025 q1 dividends. O 2025 Q1 Dividends Lease, Cost [Abstract] Finance lease cost: Deferred Income Tax Liabilities, Net Deferred income taxes Variable Rate [Domain] Variable Rate [Domain] Line of Credit Facility, Description Line of credit facility, description Restricted Cash Restricted cash Restricted cash at beginning of period Restricted Cash, Total Restricted cash at end of period Derivative Liability Natural gas swap contracts Operating Lease, Cost Operating lease cost S 2024 Q1 Dividends S 2024 Q1 Dividends [Member] S 2024 Q1 Dividends Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Walter J. Scheller, I I I [Member] Walter J. Scheller, I I I. Walter J. Scheller, III [Member] Customer D. Customer D [Member] Customer D Line of Credit Facility, Remaining Borrowing Capacity Amount of borrowings available Amount of borrowings available Second Amended And Restated Credit Agreement Second Amended And Restated Credit Agreement [Member] Second Amended and Restated Credit Agreement Base Rate [Member] Base Rate Share Repurchase Program [Axis] Share Repurchase Program [Axis] Customer [Domain] Customer [Domain] Derivative [Line Items] Derivative [Line Items] Payments for (Proceeds from) Investments Payments for (Proceeds from) Investments, Total Proceeds from (purchase of) investments Proceeds from sale of short-term investments Liabilities and Equity Total liabilities and stockholders’ equity Document Fiscal Period Focus Document Fiscal Period Focus Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Schedule of Supplemental Cash Flow Information Related to Leases Schedule of Held-to-Maturity Securities [Line Items] Schedule of Held-to-maturity Securities [Line Items] Schedule of Inventory, Current [Table Text Block] Schedule of Inventories, Net Costs and Expenses [Abstract] Costs and expenses: Letters of Credit Outstanding, Amount Letters of credit outstanding Asset Retirement Obligation, Current Asset retirement obligations Asset retirement obligations, current Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Net increase (decrease) in cash, cash equivalents and restricted cash Entity Current Reporting Status Entity Current Reporting Status Use of Estimates, Policy [Policy Text Block] Use of Estimates O 2026 Q2 Dividends O 2026 Q2 Dividends [Member] O 2026 Q2 Dividends. Fair Value, Inputs, Level 1 [Member] Level 1 Class of Stock [Domain] Class of Stock [Domain] Citibank [Member] Citibank [Member] Citibank The New Stock Repurchase Program [Member] The New Stock Repurchase Program [Member] New Stock Repurchase Program Accounts Payable, Current Accounts payable Financial Instrument [Axis] Financial Instrument [Axis] Document Transition Report Document Transition Report Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Increase (Decrease) in Inventories Inventories, net Increase (Decrease) in Other Accounts Payable and Accrued Liabilities Accrued expenses and other current liabilities Lessor, Lease, Description [Table] Lessor, Lease, Description [Table] Common Stock [Member] Common Stock Derivative Instruments and Hedging Activities Disclosure [Text Block] Derivative Instruments Credit Facility [Domain] Credit Facility [Domain] Statistical Measurement [Domain] Statistical Measurement [Domain] Customer C. Customer C [Member] Customer C Equity, Attributable to Parent [Abstract] Stockholders’ Equity: Weighted Average Number of Shares Outstanding, Basic Weighted average number of shares outstanding - basic Weighted-average shares used to compute net income (loss) per share - basic (in shares) Finance Lease, Liability, to be Paid, Remainder of Fiscal Year 2025 Assets [Abstract] ASSETS Entity Central Index Key Entity Central Index key Receivable [Policy Text Block] Trade Accounts Receivable and Allowance for Credit Losses Class of Stock [Line Items] Class of Stock [Line Items] Other Liabilities, Current Other current liabilities Consolidation Items [Axis] Consolidation Items [Axis] Current Fiscal Year End Date Current Fiscal Year End Date Derivative [Table] Derivative [Table] Document Quarterly Report Document Quarterly Report Debt Instrument, Maturity Date Debt instrument, Maturity date Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Product and Service, Revenue [Table] Revenue from External Customers by Products and Services [Table] Fair Value, Inputs, Level 2 [Member] Level 2 Net Cash Provided by (Used in) Operating Activities Net cash provided by operating activities Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Earnings Per Share, Diluted Net income per share - diluted Net income (loss) per share - diluted Dividends Dividends declared Preferred Stock, Par or Stated Value Per Share Preferred stock, par value (in dollars per share) Preferred stock, par value (in dollars per share) O 2026 Q3 Dividends Member O 2026 Q3 Dividends Member O 2026 Q3 Dividends Net income (loss) Commitments and Contingencies Disclosure [Text Block] Commitments and Contingencies Measurement Frequency [Domain] Measurement Frequency [Domain] Income Taxes Receivable, Current Income tax receivable Scenario [Domain] Scenario [Domain] Debt Instrument, Fair Value Disclosure Fair value of debt instrument Equity Components [Axis] Equity Components [Axis] Net Cash Provided by (Used in) Investing Activities [Abstract] INVESTING ACTIVITIES Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Dividends Declared [Table Text Block] Schedule of Dividends on Common Shares Increase (Decrease) in Prepaid Expense and Other Assets Prepaid expenses and other receivables Unrealized Gain (Loss) on Derivatives Unrealized gain loss on derivatives Fair Value Disclosures [Text Block] Fair Value of Financial Instruments Finance Lease, Liability, Noncurrent Noncurrent Long-term financing lease liabilities Depreciation, Depletion and Amortization Depreciation and depletion Depreciation and depletion Depreciation and depletion Depreciation and depletion Mineral Properties, Net Mineral interests, net Lessor, Lease, Description [Line Items] Lessor, Lease, Description [Line Items] Preferred Stock, Shares Authorized Preferred stock authorized (in shares) Preferred stock shares authorized (in shares) Derivative Contract [Domain] Derivative Contract [Domain] Class of Stock [Axis] Class of Stock [Axis] Deferred Income Tax Assets, Net Deferred income taxes Finance Lease, Liability, to be Paid, Maturity [Table Text Block] Schedule of Maturities of Lease Liabilities Inventory, Net Inventories, net Total inventories, net Jack K. Richardson [Member] Jack K. Richardson. Jack K. Richardson [Member] Senior Secured Notes Due 2028 Senior Secured Notes Due 2028 [Member] Senior Secured Notes Senior Secured Notes Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] Finance lease, right-of-use asset, statement of financial position [Extensible Enumeration] Accrued Liabilities, Current Accrued expenses Total accrued expenses Mining Segment [Member] Mining Segment [Member] Mining Long-Term Debt, Current Maturities Less: current debt Less: current debt Customer [Axis] Customer [Axis] Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Document Type Document Type Net Cash Provided by (Used in) Operating Activities [Abstract] OPERATING ACTIVITIES Liabilities and Equity [Abstract] LIABILITIES AND STOCKHOLDERS’ EQUITY Subsequent Event [Member] Subsequent Event Operating Income (Loss) Segment profit Operating income (loss) Asset Retirement Obligations, Noncurrent Asset retirement obligations Asset retirement obligations, noncurrent Lender Name [Axis] Lender Name [Axis] Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Table Text Block] Schedule of Revenue by Major Customers Segment Reporting [Table] Schedule of Segment Reporting Information, by Segment [Table] Lessee, Finance Lease, Remaining Lease Term Remaining lease terms Entity File Number Entity File Number Transportation and royalties. Transportation And Royalties Transportation and royalties Asset Retirement Obligation, Accretion Expense Accretion of asset retirement obligations Dividends Payable, Date of Record Record Date Retained Earnings [Member] Retained Earnings Entity Registrant Name Entity Registrant Name Accounting Policies [Abstract] Accounting Policies [Abstract] Selling, General and Administrative Expense Selling, general and administrative Selling, general and administrative Other Operating Segment [Member] All other Debt Securities, Held-to-Maturity, Restricted Debt securities, held-to-maturity, restricted Entity Address, Address Line One Entity Address, Address Line One Derivative, Number of Instruments Held Derivative, Number of Instruments Held, Total Derivative contracts outstanding Fixed Income Securities [Member] Fixed Income Securities Other Cost of Operating Revenue Cost of other revenues Cost of other revenues Cost of other revenues Cost of other revenues (exclusive of items shown separately below) Assets, Current Total current assets Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Gain (Loss) on Sale of Derivatives Gain loss on derivatives Segments [Axis] Segments [Axis] 2030 Finance Lease, Liability, to be Paid, Year Five Debt Instrument, Initial Price Of Percentage Debt Instrument, Initial Price Of Percentage Percentage of initial price Deferred Income Tax Expense (Benefit) Total deferred income tax expense (benefit) Deferred income tax benefit Entity Small Business Entity Small Business Long-Term Debt, Excluding Current Maturities Long-term debt Total long-term debt Finance Lease, Liability, to be Paid, after Year Five Thereafter Customer A. Customer A [Member] Customer A Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Dilutive restrictive stock awards Long-Term Debt, Type [Axis] Long-term Debt, Type [Axis] Significant Accounting Policies [Text Block] Summary of Significant Accounting Policies Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Accounts Receivable, after Allowance for Credit Loss, Current Trade accounts receivable Consolidation Items [Domain] Consolidation Items [Domain] Schedule of Long-Term Debt Instruments [Table Text Block] Schedule of Long-Term Debt Instruments Finance Lease, Liability, to be Paid, Year Four 2029 Energy [Axis] Energy [Axis] Permanent deduction, FDDEI Effective Income Tax Rate Reconciliation, FDDEI, Percent Earnings Per Share [Abstract] Basic and diluted net income (loss) per share: Investment, Policy [Policy Text Block] Investments Adjusted Earnings Before Interest, Taxes, Depreciation And Amortization Adjusted Earnings Before Interest, Taxes, Depreciation And Amortization Segment Adjusted EBITDA Customer E. Customer E [Member] Customer E Subsequent Event Type [Axis] Subsequent Event Type [Axis] Equity [Abstract] Equity [Abstract] Long-Term Line of Credit, Noncurrent Outstanding debt under ABL Facility Product and Service [Domain] Product and Service [Domain] Equity [Text Block] Stockholders' Equity Measurement Frequency [Axis] Measurement Frequency [Axis] Net Cash Provided by (Used in) Financing Activities [Abstract] FINANCING ACTIVITIES Federal Coal Lease Liability Current Federal coal lease liability current. Federal coal lease obligations Short-term federal coal lease obligations Line of Credit Facility, Lender [Domain] Line of Credit Facility, Lender [Domain] Entity Tax Identification Number Entity Tax Identification Number Treasury Stock, Common, Shares Treasury stock (in shares) O 2025 Q3 Dividends [Member] O 2025 Q3 Dividends. O 2025 Q3 Dividends Derivative Instrument [Axis] Derivative Instrument [Axis] Equity Component [Domain] Equity Component [Domain] O 2024 Q1 Dividends O 2024 Q1 Dividends [Member] O 2024 Q1 Dividends Entity Address, City or Town Entity Address, City or Town Credit Adjustment Spread Credit Adjustment Spread [Member] Credit Adjustment Spread Stock Issued During Period, Value, New Issues Issuance of shares Segments [Domain] Segments [Domain] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding (in shares) The First Stock Repurchase Program [Member] The First Stock Repurchase Program [Member] The First Stock Repurchase Program Self Insurance Reserve, Noncurrent Black lung obligations Black lung obligations, noncurrent Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Denominator: Share repurchase program, shares purchased to date. Share Repurchase Program, Shares Purchased To Date Shares repurchased (in shares) Payments to Acquire Other Property, Plant, and Equipment Purchase of property, plant and equipment Statement [Table] Statement [Table] Lease, Cost Net lease cost Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income before income tax expense Income before income taxes Income (loss) before income tax expense (benefit) Segment Reporting, Reconciliation of Profit (Loss) by Segment to Consolidated [Table Text Block] Schedule of Reconciliation of Segment Adjusted EBITDA to Net Income (Loss) Entity Shell Company Entity Shell Company Net Cash Provided by (Used in) Investing Activities Net cash used in investing activities Statement [Line Items] Statement [Line Items] 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] Maximum [Member] Maximum Federal Coal Lease Liability Noncurrent Federal coal lease liability noncurrent. Federal coal lease obligations Long-term federal coal lease obligations Debt Disclosure [Abstract] Debt Disclosure [Abstract] Finance Lease, Liability, to be Paid Total Lease liability Investment Income, Interest Interest income Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Statutory federal income tax rate Payments to Acquire Mining Assets Deferred mine development costs Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation Tax withholdings on vested equity awards Payment, Tax Withholding, Share-Based Payment Arrangement Payments for taxes related to net share settlement of equity awards O 2024 Q2 Dividends O 2024 Q2 Dividends [Member] O 2024 q2 dividends. Finance Lease, Liability, Current Current Short-term financing lease liabilities Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Product and Service, Revenue [Line Items] Revenue from External Customer [Line Items] Leases [Abstract] Leases [Abstract] Document Fiscal Year Focus Document Fiscal Year Focus Common Stock, Shares, Outstanding Common stock outstanding (in shares) Common stock shares outstanding (in shares) Financial Instruments [Domain] Financial Instruments [Domain] Revenue from Contract with Customer [Policy Text Block] Revenue Recognition Forecast [Member] Forecast Secured Overnight Financing Rate (SOFR) [Member] Secured Overnight Financing Rate (SOFR) Security Exchange Name Security Exchange Name Revenues Revenues Revenues, Total Finance Lease, Weighted Average Discount Rate, Percent Weighted average discount rate - finance leases (as a percent) Derivative, Gain (Loss) on Derivative, Net Mark-to-market loss on gas hedges Mark-to-market net loss on gas hedges 1.6 Realized losses on derivatives Entity Address, State or Province Entity Address, State or Province Amendment Flag Amendment Flag Finance Lease, Liability, to be Paid, Gross Difference [Abstract] Finance lease liabilities Effective Income Tax Rate Reconciliation, Tax Credit, Energy-Related, Percent Tax credit on eligible production costs Net Income (Loss) Available to Common Stockholders, Diluted [Abstract] Numerator: Debt Instrument [Axis] Debt Instrument [Axis] Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents Cash, cash equivalents and restricted cash at end of period Cash, cash equivalents and restricted cash at beginning of period Cash, cash equivalents and restricted cash City Area Code City Area Code Interest Expense, Nonoperating Interest expense Interest expense Preferred Stock [Member] Preferred Stock Other Operating Activities, Cash Flow Statement Other Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization Property, plant and equipment, net Property, plant and equipment, net Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Cash, Cash Equivalents and Restricted Cash Inventory Disclosure [Text Block] Inventories, net Payable Date Dividends Payable, Date to be Paid Common Stock, Par or Stated Value Per Share Common stock, par value (in dollars per share) Finance Lease, Liability, to be Paid, Year One 2026 Lease liability first installment Liabilities, Current Total current liabilities Segment Reporting [Text Block] Segment Information Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract] Trading Symbol Trading Symbol Share Repurchase Program [Domain] Share Repurchase Program [Domain] Finance Lease, Weighted Average Remaining Lease Term Weighted average remaining lease term - finance leases (in months) Finance Lease, Right-of-Use Asset, Amortization Amortization of leased assets Amortization of Debt Issuance Costs and Discounts Amortization of debt issuance costs and debt discount Revenue from Contract with Customer, Including Assessed Tax Other revenues Total revenues Entity Emerging Growth Company Entity Emerging Growth Company Dividends Payable, Date Declared Declaration Date Additional Paid-in Capital [Member] Additional Paid in Capital Dividends [Axis] Dividends [Axis] Long-Term Debt, Gross Long-term debt, gross Finance lease principal payments inflows (outflows). Finance Lease, Principal Payments, Inflows (Outflows) Financing cash flows from finance leases Finance Lease, Liability Present value of lease liabilities Total finance lease liabilities Payments of Dividends Dividends paid Dividends Paid Cover [Abstract] Cover [Abstract] Segment Reporting, Other Segment Item, Amount Other segment items Debt Securities, Held-to-Maturity [Table] Debt Securities, Held-to-maturity [Table] Long-Term Debt, Type [Domain] Long-term Debt, Type [Domain] Cash And Fixed Income Securities [Member] Cash And Fixed Income Securities [Member] Cash and Fixed Income Securities Amended Revolving Credit Facility [Member] Amended revolving credit facility. Amended ABL Facility Amended ABL Borrowings Share-Based Payment Arrangement, Noncash Expense Stock based compensation expense Additional Paid in Capital Additional paid in capital Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income (loss) to net cash provided by operating activities: O 2024 Q4 Dividends [Member] O 2024 q4 dividends. O 2024 Q4 Dividends Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents Cash and cash equivalents at beginning of period Cash and Cash Equivalent, Total Cash and cash equivalents at end of period Share Repurchase Program, Remaining Authorized, Amount Remaining authorized repurchase amount Remaining authorized repurchase amount Natural Gas [Member] Natural Gas Net Cash Provided by (Used in) Financing Activities Net cash (used in) provided by financing activities Lessee, Operating And Finance Leases, Supplemental Cash Flow Information [Abstract] Lessee, Operating And Finance Leases, Supplemental Cash Flow Information [Abstract] Cash paid (received) for amounts included in the measurement of lease liabilities: Entity Filer Category Entity Filer Category Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Increase (Decrease) in Accounts Receivable Trade accounts receivable Inventory Disclosure [Abstract] Inventory Disclosure [Abstract] Share repurchase program, shares purchases to date, amount. Share Repurchase Program, Shares Purchases To Date, Amount Shares repurchased, value Document Information [Line Items] Document Information [Line Items] Segment Reporting [Abstract] Segment Reporting [Abstract] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Finance Lease, Principal Payments Financing cash flows from finance leases Principal repayments of finance lease obligations Local Phone Number Local Phone Number