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Fair Value Measurements - Available-for-Sale Securities Measured at Fair Value (Detail) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Schedule Of Available For Sale Securities [Line Items]    
Available-for-sale securities $ 2,151us-gaap_AvailableForSaleSecurities $ 3,915us-gaap_AvailableForSaleSecurities
Mutual funds [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Available-for-sale securities 751us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= mdr_MutualFundsMember		 2,216us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= mdr_MutualFundsMember
Commercial paper [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Available-for-sale securities 1,400us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CommercialPaperNotIncludedWithCashAndCashEquivalentsMember		 1,699us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CommercialPaperNotIncludedWithCashAndCashEquivalentsMember
Level 2 [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Available-for-sale securities 2,151us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member		 3,915us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
Level 2 [Member] | Mutual funds [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Available-for-sale securities 751us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= mdr_MutualFundsMember		 2,216us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= mdr_MutualFundsMember
Level 2 [Member] | Commercial paper [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Available-for-sale securities $ 1,400us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CommercialPaperNotIncludedWithCashAndCashEquivalentsMember		 $ 1,699us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CommercialPaperNotIncludedWithCashAndCashEquivalentsMember