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 | us-gaap:HedgingAssetsCurrent | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfFinancialPositionClassified-RealEstateOperations |
 | us-gaap:DerivativeInstrumentsAndHedges | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfFinancialPositionClassified-RealEstateOperations |
 | us-gaap:DerivativeAssetsCurrent | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfFinancialPositionClassified-RealEstateOperationsStatementTable |
 | us-gaap:HedgingAssetsCurrent | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfFinancialPositionClassified-RealEstateOperationsStatementTable |
 | us-gaap:DerivativeInstrumentsAndHedges | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfFinancialPositionClassified-RealEstateOperationsStatementTable |
 | us-gaap:DerivativeAssetsCurrent | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfFinancialPositionClassified |
 | us-gaap:HedgingAssetsCurrent | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfFinancialPositionClassified |
 | us-gaap:CommodityContractAssetCurrent | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfFinancialPositionClassified |
 | us-gaap:EnergyMarketingContractsAssetsCurrent | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfFinancialPositionClassified |
 | us-gaap:DerivativeInstrumentsAndHedges | parent-child | http://fasb.org/us-gaap/role/statement/StatementOfFinancialPositionClassified |
 | us-gaap:DerivativeAssetsCurrent | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfFinancialPositionClassifiedStatementTable |
 | us-gaap:HedgingAssetsCurrent | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfFinancialPositionClassifiedStatementTable |
 | us-gaap:CommodityContractAssetCurrent | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfFinancialPositionClassifiedStatementTable |
 | us-gaap:EnergyMarketingContractsAssetsCurrent | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfFinancialPositionClassifiedStatementTable |
 | us-gaap:DerivativeInstrumentsAndHedges | domain-member | http://fasb.org/us-gaap/role/statement/StatementOfFinancialPositionClassifiedStatementTable |