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EMPLOYEE RETIREMENT SAVINGS PLAN (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 27, 2014
Dec. 28, 2013
Dec. 29, 2012
EMPLOYEE RETIREMENT SAVINGS PLAN      
Employee contribution limit per calendar year to 401 (k) plan 50.00%vmi_DefinedContributionPlanEmployeeContributionLimitPercentageOfCompensation    
Company contributions $ 12,600us-gaap_DefinedContributionPlanCostRecognized $ 11,600us-gaap_DefinedContributionPlanCostRecognized $ 10,000us-gaap_DefinedContributionPlanCostRecognized
Assets related to non-qualified deferred compensation plan included in other assets 36,439us-gaap_DeferredCompensationPlanAssets 27,133us-gaap_DeferredCompensationPlanAssets  
Liabilities related to non-qualified deferred compensation plan included in other noncurrent liabilities 36,439vmi_DeferredCompensationLiabilitiesNoncurrent 27,133vmi_DeferredCompensationLiabilitiesNoncurrent  
Total amount distributed from non-qualified deferred compensation plan $ 1,519us-gaap_DeferredCompensationArrangementWithIndividualDistributionsPaid $ 1,626us-gaap_DeferredCompensationArrangementWithIndividualDistributionsPaid