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Commitments and Contingencies (Details) (USD $) In Millions, except Per Share data, unless otherwise specified | 1 Months Ended | 12 Months Ended | 36 Months Ended |  |
--- | --- | --- | --- | --- | ---
Oct. 31, 2012 | Dec. 27, 2014 | Dec. 28, 2013 | Dec. 29, 2012 | Dec. 27, 2014 | Dec. 25, 2010 | Jun. 21, 2011
Site Contingency [Line Items] |  |  |  |  |  |  |
Environmental expense |  | $ 1.2 us-gaap_EnvironmentalRemediationExpense | $ 1.0 us-gaap_EnvironmentalRemediationExpense | $ 3.1 us-gaap_EnvironmentalRemediationExpense |  |  |
Environmental reserves |  | 22.7 us-gaap_AccrualForEnvironmentalLossContingencies | 23.6 us-gaap_AccrualForEnvironmentalLossContingencies |  | 22.7 us-gaap_AccrualForEnvironmentalLossContingencies |  |
Expected environmental expenditures for 2015 |  | 0.7 us-gaap_AccrualForEnvironmentalLossContingenciesUndiscountedDueWithinOneYear |  |  | 0.7 us-gaap_AccrualForEnvironmentalLossContingenciesUndiscountedDueWithinOneYear |  |
Expected environmental expenditures for 2016 |  | 0.8 us-gaap_AccrualForEnvironmentalLossContingenciesUndiscountedDueInSecondYear |  |  | 0.8 us-gaap_AccrualForEnvironmentalLossContingenciesUndiscountedDueInSecondYear |  |
Expected environmental expenditures for 2017 |  | 0.7 us-gaap_AccrualForEnvironmentalLossContingenciesUndiscountedDueInThirdYear |  |  | 0.7 us-gaap_AccrualForEnvironmentalLossContingenciesUndiscountedDueInThirdYear |  |
Expected environmental expenditures for 2018 |  | 0.7 us-gaap_AccrualForEnvironmentalLossContingenciesUndiscountedDueInFourthYear |  |  | 0.7 us-gaap_AccrualForEnvironmentalLossContingenciesUndiscountedDueInFourthYear |  |
Expected environmental expenditures for 2019 |  | 0.8 us-gaap_AccrualForEnvironmentalLossContingenciesUndiscountedDueInFifthYear |  |  | 0.8 us-gaap_AccrualForEnvironmentalLossContingenciesUndiscountedDueInFifthYear |  |
Expected environmental expenditures after 2019 |  | 9.4 us-gaap_AccrualForEnvironmentalLossContingenciesUndiscountedDueAfterFifthYear |  |  | 9.4 us-gaap_AccrualForEnvironmentalLossContingenciesUndiscountedDueAfterFifthYear |  |
Gain Contingencies [Line Items] |  |  |  |  |  |  |
Proceeds from legal settlements | 5.8 us-gaap_ProceedsFromLegalSettlements |  |  |  |  |  |
Consulting Agreement [Member] |  |  |  |  |  |  |
Long-term Purchase Commitment [Line Items] |  |  |  |  |  |  |
Consulting agreement term (in years) |  | 6 years |  |  |  |  |
Initial period of the consulting agreement |  | 4 years |  |  |  |  |
Initial period rate of pay based on final base compensation (in hundredths) |  | two-thirds |  |  |  |  |
Final period of the consulting agreement |  | 2 years |  |  |  |  |
Final period rate of pay of based on final base compensation (in hundredths) |  | one-third |  |  |  |  |
Remaining amount payable under the Consulting agreement |  | 2.7 mli_ConsultingAgreementMaximumPayable / us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis = mli_ConsultingAgreementMember |  |  | 2.7 mli_ConsultingAgreementMaximumPayable / us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis = mli_ConsultingAgreementMember |  |
Facilities Vehicles and Equipment [Member] |  |  |  |  |  |  |
Operating Leased Assets [Line Items] |  |  |  |  |  |  |
Lease payments scheduled for 2015 |  | 6.2 us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_VehiclesMember |  |  | 6.2 us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_VehiclesMember |  |
Lease payments scheduled for 2016 |  | 3.9 us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_VehiclesMember |  |  | 3.9 us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_VehiclesMember |  |
Lease payments scheduled for 2017 |  | 2.6 us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_VehiclesMember |  |  | 2.6 us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_VehiclesMember |  |
Lease payments scheduled for 2018 |  | 2.1 us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_VehiclesMember |  |  | 2.1 us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_VehiclesMember |  |
Lease payments scheduled for 2019 |  | 0.4 us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_VehiclesMember |  |  | 0.4 us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_VehiclesMember |  |
Lease expense |  | 9.8 us-gaap_OperatingLeasesRentExpenseNet / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_VehiclesMember | 9.1 us-gaap_OperatingLeasesRentExpenseNet / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_VehiclesMember | 8.5 us-gaap_OperatingLeasesRentExpenseNet / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_VehiclesMember |  |  |
Insurance Settlement [Member] | Fulton, Mississippi [Member] |  |  |  |  |  |  |
Gain Contingencies [Line Items] |  |  |  |  |  |  |
Pre-tax gain from settlement |  |  |  | 1.5 us-gaap_FormerGainContingencyRecognizedInCurrentPeriod / us-gaap_GainContingenciesByNatureAxis = us-gaap_InsuranceSettlementMember / mli_LocationOfInsurableActionAxis = mli_FultonMississippiMember |  | 1.5 us-gaap_FormerGainContingencyRecognizedInCurrentPeriod / us-gaap_GainContingenciesByNatureAxis = us-gaap_InsuranceSettlementMember / mli_LocationOfInsurableActionAxis = mli_FultonMississippiMember |
Insurance Settlement [Member] | Wynne, Arkansas [Member] |  |  |  |  |  |  |
Gain Contingencies [Line Items] |  |  |  |  |  |  |
Insurance settlement proceeds |  |  | 127.3 us-gaap_GainContingencyUnrecordedAmount / us-gaap_GainContingenciesByNatureAxis = us-gaap_InsuranceSettlementMember / mli_LocationOfInsurableActionAxis = mli_WynneArkansasMember |  |  |  |
Insurance claim deductible amount |  |  | 0.5 mli_InsuranceClaimDeductibleAmount / us-gaap_GainContingenciesByNatureAxis = us-gaap_InsuranceSettlementMember / mli_LocationOfInsurableActionAxis = mli_WynneArkansasMember |  |  |  |
Pre-tax gain from settlement |  |  | 106.3 us-gaap_FormerGainContingencyRecognizedInCurrentPeriod / us-gaap_GainContingenciesByNatureAxis = us-gaap_InsuranceSettlementMember / mli_LocationOfInsurableActionAxis = mli_WynneArkansasMember |  |  |  |
Pre-tax gain from settlement (in dollars per share) |  |  | $ 1.17 mli_FormerGainContingencyRecognizedInCurrentPeriodDollarsPerShare / us-gaap_GainContingenciesByNatureAxis = us-gaap_InsuranceSettlementMember / mli_LocationOfInsurableActionAxis = mli_WynneArkansasMember |  |  |  |
Proceeds from insurance company received |  |  | 62.3 us-gaap_UnusualOrInfrequentItemInsuranceProceeds / us-gaap_GainContingenciesByNatureAxis = us-gaap_InsuranceSettlementMember / mli_LocationOfInsurableActionAxis = mli_WynneArkansasMember | 55.0 us-gaap_UnusualOrInfrequentItemInsuranceProceeds / us-gaap_GainContingenciesByNatureAxis = us-gaap_InsuranceSettlementMember / mli_LocationOfInsurableActionAxis = mli_WynneArkansasMember |  |  |
United States Department of Commerce Antidumping Review [Member] |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |
Assignment of antidumping duty rate on U.S. imports by Company subsidiaries (in hundredths) |  |  |  |  |  |  | 19.80%mli_AssignmentOfAntidumpingDutyRateOnUSImportsByCompanySubsidiaries / us-gaap_LossContingenciesByNatureOfContingencyAxis = us-gaap_UnfavorableRegulatoryActionMember
Reserve established |  | 1.1 us-gaap_LossContingencyAccrualAtCarryingValue / us-gaap_LossContingenciesByNatureOfContingencyAxis = us-gaap_UnfavorableRegulatoryActionMember |  |  | 1.1 us-gaap_LossContingencyAccrualAtCarryingValue / us-gaap_LossContingenciesByNatureOfContingencyAxis = us-gaap_UnfavorableRegulatoryActionMember |  |
Operating Properties [Member] | Mueller Copper Tube Products, Inc. [Member] |  |  |  |  |  |  |
Site Contingency [Line Items] |  |  |  |  |  |  |
Mitigation estimates minimum |  | 0.8 us-gaap_EnvironmentalExitCostsReasonablyPossibleAdditionalLossesLowEstimate / us-gaap_EnvironmentalRemediationSiteAxis = mli_MuellerCopperTubeProductsIncMember / mli_OperatingStatusAxis = mli_OperatingPropertiesMember |  |  |  |  |
Mitigation estimates maximum |  | 1.3 us-gaap_EnvironmentalExitCostsReasonablyPossibleAdditionalLossesHighEstimate / us-gaap_EnvironmentalRemediationSiteAxis = mli_MuellerCopperTubeProductsIncMember / mli_OperatingStatusAxis = mli_OperatingPropertiesMember |  |  |  |  |
Estimated number of years until mitigation resolution |  | 10 years |  |  |  |  |
Non-Operating Properties [Member] | Southeast Kansas Sites [Member] |  |  |  |  |  |  |
Site Contingency [Line Items] |  |  |  |  |  |  |
Environmental reserves |  | 9.5 us-gaap_AccrualForEnvironmentalLossContingencies / us-gaap_EnvironmentalRemediationSiteAxis = mli_SoutheastKansasSitesMember / mli_OperatingStatusAxis = mli_NonOperatingPropertiesMember |  |  | 9.5 us-gaap_AccrualForEnvironmentalLossContingencies / us-gaap_EnvironmentalRemediationSiteAxis = mli_SoutheastKansasSitesMember / mli_OperatingStatusAxis = mli_NonOperatingPropertiesMember |  |
Number of parties involved in settlement negotiations |  | 2 mli_NumberOfPartiesInvolvedInSettlementNegotiations / us-gaap_EnvironmentalRemediationSiteAxis = mli_SoutheastKansasSitesMember / mli_OperatingStatusAxis = mli_NonOperatingPropertiesMember |  |  | 2 mli_NumberOfPartiesInvolvedInSettlementNegotiations / us-gaap_EnvironmentalRemediationSiteAxis = mli_SoutheastKansasSitesMember / mli_OperatingStatusAxis = mli_NonOperatingPropertiesMember |  |
Non-Operating Properties [Member] | Shasta Area Mine Sites [Member] |  |  |  |  |  |  |
Site Contingency [Line Items] |  |  |  |  |  |  |
Environmental spending |  |  |  |  | 1.7 mli_EnvironmentalRemediationExpenseSpending / us-gaap_EnvironmentalRemediationSiteAxis = mli_ShastaAreaMineSitesMember / mli_OperatingStatusAxis = mli_NonOperatingPropertiesMember |  |
Period of permit, implementation of Best Management Practices |  | 10 years |  |  |  |  |
Mitigation estimates minimum |  | 10.5 us-gaap_EnvironmentalExitCostsReasonablyPossibleAdditionalLossesLowEstimate / us-gaap_EnvironmentalRemediationSiteAxis = mli_ShastaAreaMineSitesMember / mli_OperatingStatusAxis = mli_NonOperatingPropertiesMember |  |  |  |  |
Mitigation estimates maximum |  | 13.0 us-gaap_EnvironmentalExitCostsReasonablyPossibleAdditionalLossesHighEstimate / us-gaap_EnvironmentalRemediationSiteAxis = mli_ShastaAreaMineSitesMember / mli_OperatingStatusAxis = mli_NonOperatingPropertiesMember |  |  |  |  |
Estimated number of years until mitigation resolution |  | 20 years |  |  |  |  |
Non-Operating Properties [Member] | Lead Refinery Site [Member] |  |  |  |  |  |  |
Site Contingency [Line Items] |  |  |  |  |  |  |
Environmental expense |  | 0.1 us-gaap_EnvironmentalRemediationExpense / us-gaap_EnvironmentalRemediationSiteAxis = mli_LeadRefinerySiteMember / mli_OperatingStatusAxis = mli_NonOperatingPropertiesMember | 0.1 us-gaap_EnvironmentalRemediationExpense / us-gaap_EnvironmentalRemediationSiteAxis = mli_LeadRefinerySiteMember / mli_OperatingStatusAxis = mli_NonOperatingPropertiesMember | 0.1 us-gaap_EnvironmentalRemediationExpense / us-gaap_EnvironmentalRemediationSiteAxis = mli_LeadRefinerySiteMember / mli_OperatingStatusAxis = mli_NonOperatingPropertiesMember |  |  |
Number of parties involved in settlement negotiations |  | 3 mli_NumberOfPartiesInvolvedInSettlementNegotiations / us-gaap_EnvironmentalRemediationSiteAxis = mli_LeadRefinerySiteMember / mli_OperatingStatusAxis = mli_NonOperatingPropertiesMember |  |  | 3 mli_NumberOfPartiesInvolvedInSettlementNegotiations / us-gaap_EnvironmentalRemediationSiteAxis = mli_LeadRefinerySiteMember / mli_OperatingStatusAxis = mli_NonOperatingPropertiesMember |  |
Mitigation estimates minimum |  | 1.9 us-gaap_EnvironmentalExitCostsReasonablyPossibleAdditionalLossesLowEstimate / us-gaap_EnvironmentalRemediationSiteAxis = mli_LeadRefinerySiteMember / mli_OperatingStatusAxis = mli_NonOperatingPropertiesMember |  |  |  |  |
Mitigation estimates maximum |  | 3.6 us-gaap_EnvironmentalExitCostsReasonablyPossibleAdditionalLossesHighEstimate / us-gaap_EnvironmentalRemediationSiteAxis = mli_LeadRefinerySiteMember / mli_OperatingStatusAxis = mli_NonOperatingPropertiesMember |  |  |  |  |
Estimated number of years until mitigation resolution |  | 20 years |  |  |  |  |
Lead Refinery Site [Abstract] |  |  |  |  |  |  |
EPA's estimated cost of site remediation |  | $ 26.0 us-gaap_SiteContingencyLossExposureNotAccruedBestEstimate / us-gaap_EnvironmentalRemediationSiteAxis = mli_LeadRefinerySiteMember / mli_OperatingStatusAxis = mli_NonOperatingPropertiesMember |  |  |  |  |
Number of surrounding properties |  | 300 mli_NumberOfSurroundingProperties / us-gaap_EnvironmentalRemediationSiteAxis = mli_LeadRefinerySiteMember / mli_OperatingStatusAxis = mli_NonOperatingPropertiesMember |  |  |  |  |

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