XML 105 R84.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Inventories Details Textuals (Details) - Reserve for materials and supplies [Member] - USD ($) $ in Millions | Dec. 31, 2017 | Apr. 01, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
--- | --- | --- | --- | --- | ---
Successor |  |  |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |  |  |
Materials and supplies reserves | $ 0.6 | $ 0.0 |  |  |
Predecessor |  |  |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |  |  |
Materials and supplies reserves |  | $ 0.0 | $ 5.6 | $ 4.7 | $ 4.6

X
- Definition Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690 + Details
Name: | us-gaap_ValuationAllowancesAndReservesBalance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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_ValuationAndQualifyingAccountsDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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

X
- Details
Name: | us-gaap_ValuationAllowancesAndReservesTypeAxis=btu_ReserveForMaterialsAndSuppliesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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