XML 147 R129.htm IDEA: XBRL DOCUMENT
v3.6.0.2

Financial Instruments (Details) $ in Millions | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Sep. 30, 2016 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($) | Jul. 26, 2016 USD ($)
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | $ 2,015.5 |  |  |
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract] |  |  |  |  |  |
Amount in bank guarantees, letters of credit and surety bonds related to road maintenance, performance guarantees and other operations |  |  | 121.0 |  |  |
Amount in Letters of Credit Held as Collateral in Support of Surety Bonds |  |  | 48.0 |  |  |
Amount in letters of credit issued as collateral to support surety bonds |  |  | 72.6 |  |  |
Cash collateral in support of reclamation obligations or activities |  |  | 233.2 |  |  |
Letters of credit in support of reclamation obligations or activities |  | $ 15.7 | 80.0 | $ 126.6 |  |
Total consideration received by Company related to accounts receivable sold under securitization program |  |  | 2,859.9 |  |  |
Cash up front from sale of receivables |  |  | 1,541.7 |  |  |
Additional cash upon collection of underlying receivables |  |  | 1,155.3 |  |  |
Non collected receivables |  |  | 162.9 |  |  |
Reduction in accounts receivable as a result of securitization activity |  |  |  | 168.5 |  |
Expense associated with securitization transactions |  |  | 8.2 | 1.8 | $ 1.5 |
Restricted Cash and Investments, Current |  |  | 54.3 | 0.0 |  |
Maximum Capacity of Securitization Program |  |  | 180.0 | $ 275.0 |  |
Restricted Cash and Cash Equivalents |  |  | 40.5 |  |  |
Restricted Cash and Investments, Noncurrent |  |  | 71.4 |  |  |
DTA and PBGC [Member] |  |  |  |  |  |
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract] |  |  |  |  |  |
Letters of credit outstanding |  |  | $ 37.0 |  |  |
Dominion Terminal Associates Partnership [Member] |  |  |  |  |  |
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract] |  |  |  |  |  |
Ownership percentage of equity method investment |  |  | 37.50% |  |  |
DTA Lease Term |  |  | 30 |  |  |
Pension Plans Agreement With PBG and TXU Europe [Member] |  |  |  |  |  |
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract] |  |  |  |  |  |
Defined benefit pension plans requiring special contributions |  |  | 2 |  |  |
Letter of credit maintained by the Company in favor of the PBGC |  |  | $ 37.0 |  |  |
Guarantee in place from TXU Europe Limited |  |  | 110.0 |  |  |
Reclamation Obligations [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 1,701.7 |  |  |
Coal Lease Obligations [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 94.0 |  |  |
Workers' Compensation Obligations [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 61.8 |  |  |
Other [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk | [1] |  | 158.0 |  |  |
Financial Standby Letter of Credit [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 381.5 |  |  |
Self bonding [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 1,094.2 |  |  |
Self bonding [Member] | Reclamation Obligations [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 1,094.2 |  |  |
Self bonding [Member] | Coal Lease Obligations [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 0.0 |  |  |
Self bonding [Member] | Workers' Compensation Obligations [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 0.0 |  |  |
Self bonding [Member] | Other [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk | [1] |  | 0.0 |  |  |
Self bonding [Member] | Financial Standby Letter of Credit [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 0.0 |  |  |
Surety Bond [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 448.2 |  |  |
Surety Bond [Member] | Reclamation Obligations [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 319.6 |  |  |
Surety Bond [Member] | Coal Lease Obligations [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 94.0 |  |  |
Surety Bond [Member] | Workers' Compensation Obligations [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 19.1 |  |  |
Surety Bond [Member] | Other [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk | [1] |  | 15.5 |  |  |
Surety Bond [Member] | Financial Standby Letter of Credit [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk | [2] |  | 64.5 |  |  |
Bank Guarantees [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 79.2 |  |  |
Bank Guarantees [Member] | Reclamation Obligations [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 54.7 |  |  |
Bank Guarantees [Member] | Coal Lease Obligations [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 0.0 |  |  |
Bank Guarantees [Member] | Workers' Compensation Obligations [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 0.0 |  |  |
Bank Guarantees [Member] | Other [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk | [1] |  | 24.5 |  |  |
Bank Guarantees [Member] | Financial Standby Letter of Credit [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 83.8 |  |  |
Letters of credit [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 393.9 |  |  |
Letters of credit [Member] | Reclamation Obligations [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 233.2 |  |  |
Letters of credit [Member] | Coal Lease Obligations [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 0.0 |  |  |
Letters of credit [Member] | Workers' Compensation Obligations [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 42.7 |  |  |
Letters of credit [Member] | Other [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk | [1] |  | 118.0 |  |  |
Letters of credit [Member] | Financial Standby Letter of Credit [Member] |  |  |  |  |  |
Guarantee Obligations [Line Items] |  |  |  |  |  |
Financial instruments with off balance sheet risk |  |  | 233.2 |  |  |
Parent Company [Member] |  |  |  |  |  |
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract] |  |  |  |  |  |
Restricted Cash and Investments, Current |  |  | 13.8 |  |  |
Wyoming [Member] | Self bonding [Member] | Reclamation Obligations [Member] |  |  |  |  |  |
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract] |  |  |  |  |  |
Letters of credit in support of reclamation obligations or activities |  |  |  |  |  | $ 0.8
Indiana [Member] | Self bonding [Member] | Reclamation Obligations [Member] |  |  |  |  |  |
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract] |  |  |  |  |  |
Letters of credit in support of reclamation obligations or activities |  |  |  |  |  | 7.5
Illinois [Member] | Self bonding [Member] | Reclamation Obligations [Member] |  |  |  |  |  |
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract] |  |  |  |  |  |
Letters of credit in support of reclamation obligations or activities |  |  |  |  |  | $ 3.2
Scenario, Actual [Member] | Dominion Terminal Associates Partnership [Member] |  |  |  |  |  |
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract] |  |  |  |  |  |
Repayments of Lines of Credit |  | 39.9 |  |  |  |
Line of Credit Assumed |  | $ 42.7 |  |  |  |
U.S Mining [Member] |  |  |  |  |  |
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract] |  |  |  |  |  |
Surety Bonds Outstanding For Reclamation |  |  | 1,413.8 |  |  |
Costs Incurred, Asset Retirement Obligation Incurred |  |  | 471.1 |  |  |
Australian Mining [Member] |  |  |  |  |  |
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract] |  |  |  |  |  |
Costs Incurred, Asset Retirement Obligation Incurred |  |  | 287.7 |  |  |
Cash collateral in support of reclamation obligations or activities |  |  | $ 233.2 |  |  |
[1] | Other includes the $37.0 million in letters of credit related to the PBGC, as described below, and an additional $121.0 million in bank guarantees, letters of credit and surety bonds related to road maintenance, performance guarantees and other operations.
[2] | A total of $72.6 million of letters of credit issued as collateral to support surety bonds related to Patriot have been excluded from above as they no longer represent off-balance sheet obligations as discussed in Note 27. "Matters Related to the Bankruptcy of Patriot Coal Corporation".

X
- Definition Additional cash upon collection of underlying receivables. + References No definition available. + Details
Name: | btu_AdditionalCashUponCollectionOfUnderlyingReceivables
Namespace Prefix: | btu_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount in letters of credit and surety bonds related to collateral for surety companies, road maintenance, performance guarantees and other operations. + References No definition available. + Details
Name: | btu_AmountInLettersOfCreditAndSuretyBondsRelatedToCollateralForSuretyCompaniesRoadMaintenancePerformanceGuaranteesAndOtherOperations
Namespace Prefix: | btu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount In Letters Of Credit Issued As Collateral To Support Surety Bonds. + References No definition available. + Details
Name: | btu_AmountInLettersOfCreditIssuedAsCollateralToSupportSuretyBonds
Namespace Prefix: | btu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount in Letters of Credit Held as Collateral in Support of Surety Bonds + References No definition available. + Details
Name: | btu_AmountinLettersofCreditHeldasCollateralinSupportofSuretyBonds
Namespace Prefix: | btu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Cash up front from sale of receivables. + References No definition available. + Details
Name: | btu_CashUpFrontFromSaleOfReceivables
Namespace Prefix: | btu_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Cash collateral in support of reclamation obligations or activities + References No definition available. + Details
Name: | btu_Cashcollateralinsupportofreclamationobligationsoractivities
Namespace Prefix: | btu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Consideration Received By Company Related To Securitization Program. + References No definition available. + Details
Name: | btu_ConsiderationReceivedByCompanyRelatedToSecuritizationProgram
Namespace Prefix: | btu_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The Company is required to make special contributions to two of the Company's defined benefit pension plans. + References No definition available. + Details
Name: | btu_Definedbenefitpensionplansrequiringspecialcontributions
Namespace Prefix: | btu_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Term of lease held by Dominion Terminal Associates, an equity method investee, for a coal export terminal in Newport News, Virginia. + References No definition available. + Details
Name: | btu_DtaLeaseTerm
Namespace Prefix: | btu_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Guarantee In Place From Affiliate. + References No definition available. + Details
Name: | btu_GuaranteeInPlaceFromAffiliate
Namespace Prefix: | btu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Guarantees and Financial Instruments with Off-Balance-Sheet Risk. + References No definition available. + Details
Name: | btu_GuaranteesAndFinancialInstrumentsWithOffBalanceSheetRiskTextualsAbstract
Namespace Prefix: | btu_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Letter Of Credit maintained. + References No definition available. + Details
Name: | btu_LetterOfCreditMaintained
Namespace Prefix: | btu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Letters of credit in support of reclamation obligations or activities + References No definition available. + Details
Name: | btu_Lettersofcreditinsupportofreclamationobligationsoractivities
Namespace Prefix: | btu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Maximum capacity of the securitization program. + References No definition available. + Details
Name: | btu_MaximumCapacityOfSecuritizationProgram
Namespace Prefix: | btu_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Non collected receivables + References No definition available. + Details
Name: | btu_NonCollectedReceivables
Namespace Prefix: | btu_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Reclamation bonding requirements + References No definition available. + Details
Name: | btu_Reclamationbondingrequirements
Namespace Prefix: | btu_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of asset retirement obligations (ARO) costs incurred (whether capitalized or charged to expense) during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
Name: | us-gaap_CostsIncurredAssetRetirementObligationIncurred
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of transferred financial assets in which the transferor has continuing involvement with the assets underlying the transaction that have been derecognized. Continuing involvement includes, but is not limited to, servicing, recourse, and restrictions on transferor's interests in transferred financial assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=51814546&loc=d3e107314-111719 + Details
Name: | us-gaap_DerecognizedAssetsSecuritizedOrAssetbackedFinancingArrangementAssetsAndAnyOtherFinancialAssetsManagedTogetherPrincipalAmountOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571 + Details
Name: | us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition A gain (loss) realized on a transfer, accounted for as a sale, of all or a portion of financial assets in which the transferor surrenders control and receives consideration other than a beneficial interest in the assets transferred. Reflects the amount of sales proceeds in excess of, or deficient from, the sum of the carrying amounts of transferred financial assets plus transaction costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7,9) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 + Details
Name: | us-gaap_GainLossOnSecuritizationOfFinancialAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_GuaranteeObligationsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248 + Details
Name: | us-gaap_GuaranteeObligationsMaximumExposure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The total amount of the contingent obligation under letters of credit outstanding as of the reporting date. + References No definition available. + Details
Name: | us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The fair value of line of credit assumed in noncash investing or financing activities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4332-108586 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4313-108586 + Details
Name: | us-gaap_LineOfCreditAssumed1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of cash outflow for payment of an obligation from a lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3291-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(f)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
Name: | us-gaap_RepaymentsOfLinesOfCredit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. This element is for unclassified presentations; for classified presentations there is a separate and distinct element. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_RestrictedCashAndCashEquivalents
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The current cash, cash equivalents and investments that are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against short-term borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. Includes current cash equivalents and investments that are similarly restricted as to withdrawal, usage or disposal. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_RestrictedCashAndInvestmentsCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The noncurrent cash, cash equivalents and investments that is restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits classified as long-term; that is not expected to be released from such existing restrictions within one year of the balance sheet date or operating cycle, whichever is longer. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. Includes noncurrent cash equivalents and investments that are similarly restricted as to withdrawal, usage or disposal. + References No definition available. + Details
Name: | us-gaap_RestrictedCashAndInvestmentsNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=btu_DtaAndPbgcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=btu_DominionTerminalAssociatesPartnershipMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=btu_PensionPlansAgreementWithPbgAndTxuEuropeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_UnderlyingAssetClassAxis=btu_ReclamationObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_UnderlyingAssetClassAxis=us-gaap_PropertyLeaseGuaranteeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_UnderlyingAssetClassAxis=btu_WorkersCompensationObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_UnderlyingAssetClassAxis=us-gaap_GuaranteeTypeOtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_UnderlyingAssetClassAxis=us-gaap_FinancialStandbyLetterOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_GuaranteeObligationsByNatureAxis=btu_SelfBondingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_GuaranteeObligationsByNatureAxis=us-gaap_SuretyBondMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_GuaranteeObligationsByNatureAxis=btu_BankGuaranteesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_GuaranteeObligationsByNatureAxis=us-gaap_StandbyLettersOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=us-gaap_ParentCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=btu_WyomingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=btu_IndianaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=btu_IllinoisMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementScenarioAxis=us-gaap_ScenarioActualMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=btu_U.SMiningMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=btu_AustralianMiningMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |