1.0.0.3 false Consolidated Statements of Cash Flows (USD $) In Thousands false 1 $ false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 USDEPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 false 2 $ false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 USDEPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 false 3 $ false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 USDEPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 3 Operating activities: 1 us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 4 Net income attributable to Alpha Natural Resources, Inc. 2 us-gaap_NetIncomeLoss us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 true true 58005000 58005 false false 2 true true 165701000 165701 false false 3 true true 27734000 27734 false false No definition available. No authoritative reference available. false 5 Adjustments to reconcile net income to net cash provided by operating activities: 2 us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 6 Depreciation, depletion and amortization 3 us-gaap_DepreciationDepletionAndAmortization us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 253736000 253736 false false 2 false true 172570000 172570 false false 3 false true 159579000 159579 false false No definition available. No authoritative reference available. false 7 Amortization of acquired coal supply agreements, net 3 us-gaap_AmortizationOfIntangibleAssets us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 127608000 127608 false false 2 false true 0 0 false false 3 false true 0 0 false false No definition available. No authoritative reference available. false 8 Amortization of debt issuance costs 3 anr_AmortizationOfDebtIssuanceCosts anr false debit duration monetary Amortization of Debt Issuance Costs. false false false false false false false false false 1 false true 4689000 4689 false false 2 false true 4364000 4364 false false 3 false true 2318000 2318 false false Amortization of Debt Issuance Costs. No authoritative reference available. false 9 Mark-to-market adjustments for derivatives 3 us-gaap_UnrealizedGainLossOnDerivatives us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -3647000 -3647 false false 2 false true 47265000 47265 false false 3 false true -8925000 -8925 false false No definition available. No authoritative reference available. false 10 Accretion of asset retirement obligation 3 us-gaap_AssetRetirementObligationAccretionExpense us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 12101000 12101 false false 2 false true 7499000 7499 false false 3 false true 6845000 6845 false false No definition available. No authoritative reference available. false 11 Accretion of debt discount 3 anr_AccretionOfDebtDiscount anr false debit duration monetary Amount recognized for the passage of time, typically for liabilities, that have been discounted to their net present values.... false false false false false false false false false 1 false true 11516000 11516 false false 2 false true 7681000 7681 false false 3 false true 0 0 false false Amount recognized for the passage of time, typically for liabilities, that have been discounted to their net present values. Excludes accretion associated with asset retirement obligations. Amount recognized for the passage of time, typically for liabilities, that have been discounted to their net present values. Excludes accretion associated with asset retirement obligations. No authoritative reference available. false 12 Loss on early extinguishment of debt 3 us-gaap_GainsLossesOnExtinguishmentOfDebt us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 5641000 5641 false false 2 false true 14702000 14702 false false 3 false true 0 0 false false No definition available. No authoritative reference available. false 13 Stock-based compensation 3 us-gaap_ShareBasedCompensation us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 37802000 37802 false false 2 false true 17871000 17871 false false 3 false true 9681000 9681 false false No definition available. No authoritative reference available. false 14 Gain on sale of discontinued operations 3 us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 0 0 false false 2 false true -13622000 -13622 false false 3 false true 0 0 false false No definition available. No authoritative reference available. false 15 Gain on sale of coal reserves 3 anr_GainOnSaleOfCoalReserves anr false credit duration monetary The difference between the book value and the sale price of property that has been found to have proven coal reserves. This... false false false false false false false false false 1 false true 0 0 false false 2 false true -12936000 -12936 false false 3 false true 0 0 false false The difference between the book value and the sale price of property that has been found to have proven coal reserves. This element refers to the gain (loss). No authoritative reference available. false 16 Employee benefit plans, net 3 us-gaap_PensionAndOtherPostretirementBenefitExpense us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 30696000 30696 false false 2 false true 8673000 8673 false false 3 false true 8552000 8552 false false No definition available. No authoritative reference available. false 17 Mine closure/asset impairment charges 3 us-gaap_AssetImpairmentCharges us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 0 0 false false 2 false true 34706000 34706 false false 3 false true 0 0 false false No definition available. No authoritative reference available. false 18 Deferred income taxes 3 us-gaap_DeferredIncomeTaxExpenseBenefit us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -49754000 -49754 false false 2 false true -17107000 -17107 false false 3 false true 1032000 1032 false false No definition available. No authoritative reference available. false 19 Other, net 3 us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesOther us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 547000 547 false false 2 false true -1601000 -1601 false false 3 false true 348000 348 false false No definition available. No authoritative reference available. false 20 Changes in operating assets and liabilities: 3 us-gaap_IncreaseDecreaseInOperatingCapitalAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 21 Trade accounts receivable, net 4 us-gaap_IncreaseDecreaseInAccountsReceivable us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 14574000 14574 false false 2 false true 19674000 19674 false false 3 false true -12968000 -12968 false false No definition available. No authoritative reference available. false 22 Inventories, net 4 us-gaap_IncreaseDecreaseInInventories us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -11609000 -11609 false false 2 false true -16037000 -16037 false false 3 false true 15543000 15543 false false No definition available. No authoritative reference available. false 23 Prepaid expenses and other current assets 4 us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -40037000 -40037 false false 2 false true -1438000 -1438 false false 3 false true 8195000 8195 false false No definition available. No authoritative reference available. false 24 Other non-current assets 4 us-gaap_IncreaseDecreaseInOtherOperatingAssets us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 1080000 1080 false false 2 false true -2736000 -2736 false false 3 false true -24303000 -24303 false false No definition available. No authoritative reference available. false 25 Trade accounts payable 4 us-gaap_IncreaseDecreaseInAccountsPayable us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -26735000 -26735 false false 2 false true 14324000 14324 false false 3 false true 23548000 23548 false false No definition available. No authoritative reference available. false 26 Accrued expenses and other current liabilities 4 anr_IncreaseDecreaseInAccruedExpenseAndOtherCurrentLiabilities anr false debit duration monetary Miscellaneous liabilities expected to be paid within one year, not including current liabilities associated with debt or... false false false false false false false false false 1 false true -22384000 -22384 false false 2 false true 13864000 13864 false false 3 false true 11684000 11684 false false Miscellaneous liabilities expected to be paid within one year, not including current liabilities associated with debt or trade accounts payable. No authoritative reference available. false 27 Pension and postretirement medical benefit obligations 4 us-gaap_IncreaseDecreaseInEmployeeRelatedLiabilities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -37450000 -37450 false false 2 false true 164000 164 false false 3 false true -969000 -969 false false No definition available. No authoritative reference available. false 28 Asset retirement obligations 4 us-gaap_IncreaseDecreaseInAssetRetirementObligations us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -7298000 -7298 false false 2 false true -4825000 -4825 false false 3 false true -6124000 -6124 false false No definition available. No authoritative reference available. false 29 Other non-current liabilities 4 us-gaap_IncreaseDecreaseInOtherOperatingLiabilities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -2861000 -2861 false false 2 false true -713000 -713 false false 3 false true 3971000 3971 false false No definition available. No authoritative reference available. true 30 Net cash provided by operating activities 2 us-gaap_NetCashProvidedByUsedInOperatingActivities us-gaap true na duration monetary No definition available. false false false false false false false false false 1 false true 356220000 356220 false false 2 false true 458043000 458043 false false 3 false true 225741000 225741 false false No definition available. No authoritative reference available. true 31 Investing activities: 1 us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 32 Capital expenditures 2 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -187093000 -187093 false false 2 false true -137751000 -137751 false false 3 false true -126381000 -126381 false false No definition available. No authoritative reference available. false 33 Cash acquired from Foundation 2 us-gaap_CashAcquiredFromAcquisition us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 23505000 23505 false false 2 false true 0 0 false false 3 false true 0 0 false false No definition available. No authoritative reference available. false 34 Proceeds from disposition of property and equipment 2 us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 1197000 1197 false false 2 false true 16649000 16649 false false 3 false true 6101000 6101 false false No definition available. No authoritative reference available. false 35 Purchase of acquired companies 2 us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 0 0 false false 2 false true 0 0 false false 3 false true -43908000 -43908 false false No definition available. No authoritative reference available. false 36 Purchases of marketable securities 2 us-gaap_PaymentsToAcquireMarketableSecurities us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -119419000 -119419 false false 2 false true 0 0 false false 3 false true 0 0 false false No definition available. No authoritative reference available. false 37 Proceeds from sale of discontinued operations 2 us-gaap_ProceedsFromDivestitureOfBusinesses us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 0 0 false false 2 false true 45000000 45000 false false 3 false true 0 0 false false No definition available. No authoritative reference available. false 38 Proceeds from sale of investment in coal terminal 2 us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 0 0 false false 2 false true 1500000 1500 false false 3 false true 0 0 false false No definition available. No authoritative reference available. false 39 Investment in Dominion Terminal Facility 2 anr_InvestmentInTerminalFacility anr false credit duration monetary Investment in Dominion Terminal Facility. false false false false false false false false false 1 false true 0 0 false false 2 false true -2824000 -2824 false false 3 false true 0 0 false false Investment in Dominion Terminal Facility. No authoritative reference available. false 40 Other, net 2 us-gaap_PaymentsForProceedsFromOtherInvestingActivities us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 0 0 false false 2 false true -199000 -199 false false 3 false true -1015000 -1015 false false No definition available. No authoritative reference available. true 41 Net cash used in investing activities 2 us-gaap_NetCashProvidedByUsedInInvestingActivities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -281810000 -281810 false false 2 false true -77625000 -77625 false false 3 false true -165203000 -165203 false false No definition available. No authoritative reference available. true 42 Financing activities: 1 us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 43 Proceeds from issuance of long-term debt 2 us-gaap_ProceedsFromIssuanceOfLongTermDebt us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 0 0 false false 2 false true 287500000 287500 false false 3 false true 18900000 18900 false false No definition available. No authoritative reference available. false 44 Payments of bank overdraft 2 us-gaap_ProceedsFromRepaymentsOfBankOverdrafts us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 0 0 false false 2 false true -160000 -160 false false 3 false true -23654000 -23654 false false No definition available. No authoritative reference available. false 45 Principal repayments of note payable 2 us-gaap_RepaymentsOfNotesPayable us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -18288000 -18288 false false 2 false true -595000 -595 false false 3 false true -20941000 -20941 false false No definition available. No authoritative reference available. false 46 Principal repayments on long-term debt 2 us-gaap_RepaymentsOfLongTermDebt us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -249875000 -249875 false false 2 false true -193973000 -193973 false false 3 false true -15580000 -15580 false false No definition available. No authoritative reference available. false 47 Debt issuance costs 2 us-gaap_PaymentsOfDebtIssuanceCosts us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -13067000 -13067 false false 2 false true -10861000 -10861 false false 3 false true 0 0 false false No definition available. No authoritative reference available. false 48 Premium payment on early extinguishment of debt 2 us-gaap_PaymentsOfDebtRestructuringCosts us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 0 0 false false 2 false true -10736000 -10736 false false 3 false true 0 0 false false No definition available. No authoritative reference available. false 49 Excess tax benefit from stock-based awards 2 us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 434000 434 false false 2 false true 1980000 1980 false false 3 false true 40000 40 false false No definition available. No authoritative reference available. false 50 Proceeds from issuance of common stock, net of offering costs of $7,834 2 us-gaap_ProceedsFromIssuanceOfCommonStock us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 0 0 false false 2 false true 164666000 164666 false false 3 false true 0 0 false false No definition available. No authoritative reference available. false 51 Common stock repurchases 2 us-gaap_PaymentsForRepurchaseOfCommonStock us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -8874000 -8874 false false 2 false true 0 0 false false 3 false true 0 0 false false No definition available. No authoritative reference available. false 52 Proceeds from exercise of stock options 2 us-gaap_ProceedsFromStockOptionsExercised us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 5171000 5171 false false 2 false true 3586000 3586 false false 3 false true 3932000 3932 false false No definition available. No authoritative reference available. false 53 Other, net 2 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -232000 -232 false false 2 false true 0 0 false false 3 false true -2126000 -2126 false false No definition available. No authoritative reference available. true 54 Net cash (used in) provided by financing activities 2 us-gaap_NetCashProvidedByUsedInFinancingActivities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -284731000 -284731 false false 2 false true 241407000 241407 false false 3 false true -39429000 -39429 false false No definition available. No authoritative reference available. true 55 Net (decrease) increase in cash and cash equivalents 1 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease us-gaap true na duration monetary No definition available. false false false false false false false false false 1 false true -210321000 -210321 false false 2 false true 621825000 621825 false false 3 false true 21109000 21109 false false No definition available. No authoritative reference available. false 56 Cash and cash equivalents at beginning of period 1 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant monetary No definition available. false false false false false false true false false 1 false true 676190000 676190 false false 2 false true 54365000 54365 false false 3 false true 33256000 33256 false false No definition available. No authoritative reference available. false 57 Cash and cash equivalents at end of period 1 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant monetary No definition available. false false false false false false false true false 1 false true 465869000 465869 false false 2 false true 676190000 676190 false false 3 false true 54365000 54365 false false No definition available. No authoritative reference available. false 58 Supplemental disclosures of cash flow information: 1 us-gaap_SupplementalCashFlowInformationAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 59 Issuance of common stock for acquisition accounting 2 us-gaap_StockIssued us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 1628601000 1628601 false false 2 false true 0 0 false false 3 false true 0 0 false false No definition available. No authoritative reference available. false 60 Insurance premium financing 2 anr_InsurancePremiumFinancing anr false debit duration monetary Insurance premium financing. false false false false false false false false false 1 true true 0 0 false false 2 true true 18288000 18288 false false 3 true true 18883000 18883 false false Insurance premium financing. No authoritative reference available. false false 3 58 false Thousands UnKnown UnKnown false true