 | us-gaap:IncreaseDecreaseInAccruedSalaries | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectRealEstate |
 | us-gaap:IncreaseDecreaseInWorkersCompensationLiabilities | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectRealEstate |
 | us-gaap:IncreaseDecreaseInPostemploymentObligations | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectRealEstate |
 | us-gaap:IncreaseDecreaseInPensionAndPostretirementObligationsAbstract | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectRealEstate |
 | us-gaap:IncreaseDecreaseInOtherEmployeeRelatedLiabilities | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectRealEstate |
 | us-gaap:IncreaseDecreaseInEmployeeRelatedLiabilities | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectRealEstate |
 | us-gaap:IncreaseDecreaseInAccruedSalaries | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectRealEstateStatementTable |
 | us-gaap:IncreaseDecreaseInWorkersCompensationLiabilities | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectRealEstateStatementTable |
 | us-gaap:IncreaseDecreaseInPostemploymentObligations | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectRealEstateStatementTable |
 | us-gaap:IncreaseDecreaseInPensionAndPostretirementObligationsAbstract | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectRealEstateStatementTable |
 | us-gaap:IncreaseDecreaseInOtherEmployeeRelatedLiabilities | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectRealEstateStatementTable |
 | us-gaap:IncreaseDecreaseInEmployeeRelatedLiabilities | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectRealEstateStatementTable |
 | us-gaap:IncreaseDecreaseInAccruedSalaries | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirect |
 | us-gaap:IncreaseDecreaseInWorkersCompensationLiabilities | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirect |
 | us-gaap:IncreaseDecreaseInPostemploymentObligations | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirect |
 | us-gaap:IncreaseDecreaseInPensionAndPostretirementObligationsAbstract | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirect |
 | us-gaap:IncreaseDecreaseInPneumoconiosisBenefitObligationsNoncurrent | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirect |
 | us-gaap:IncreaseDecreaseInOtherEmployeeRelatedLiabilities | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirect |
 | us-gaap:IncreaseDecreaseInEmployeeRelatedLiabilities | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirect |
 | us-gaap:IncreaseDecreaseInAccruedSalaries | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectStatementTable |
 | us-gaap:IncreaseDecreaseInWorkersCompensationLiabilities | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectStatementTable |
 | us-gaap:IncreaseDecreaseInPostemploymentObligations | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectStatementTable |
 | us-gaap:IncreaseDecreaseInPensionAndPostretirementObligationsAbstract | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectStatementTable |
 | us-gaap:IncreaseDecreaseInPneumoconiosisBenefitObligationsNoncurrent | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectStatementTable |
 | us-gaap:IncreaseDecreaseInOtherEmployeeRelatedLiabilities | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectStatementTable |
 | us-gaap:IncreaseDecreaseInEmployeeRelatedLiabilities | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfCashFlowsIndirectStatementTable |