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           Fair Value Disclosures (Details) (Senior Notes [Member], Level 2 [Member], USD $) 
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           Mar. 31, 2015 
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           Dec. 31, 2014 
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           4.50% senior notes due 2018 [Member] 
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| Debt Instrument [Line Items] | ||
| Aggregate Principal | 
$ 175,000,000us-gaap_DebtInstrumentFaceAmount / us-gaap_DebtInstrumentAxis = mth_SeniorNotesDueTwoThousandEighteenMemberDomain / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember  | 
        
$ 175,000,000us-gaap_DebtInstrumentFaceAmount / us-gaap_DebtInstrumentAxis = mth_SeniorNotesDueTwoThousandEighteenMemberDomain / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember  | 
      
| Fair value of fixed-rate debt | ||
| Estimated Fair Value | 
177,625,000us-gaap_DebtInstrumentFairValue / us-gaap_DebtInstrumentAxis = mth_SeniorNotesDueTwoThousandEighteenMemberDomain / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember  | 
        
175,000,000us-gaap_DebtInstrumentFairValue / us-gaap_DebtInstrumentAxis = mth_SeniorNotesDueTwoThousandEighteenMemberDomain / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember  | 
      
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           7.15% senior notes due 2020 [Member] 
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| Debt Instrument [Line Items] | ||
| Aggregate Principal | 
300,000,000us-gaap_DebtInstrumentFaceAmount / us-gaap_DebtInstrumentAxis = mth_SeniorNotesDueTwoThousandTwentyMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember  | 
        
300,000,000us-gaap_DebtInstrumentFaceAmount / us-gaap_DebtInstrumentAxis = mth_SeniorNotesDueTwoThousandTwentyMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember  | 
      
| Fair value of fixed-rate debt | ||
| Estimated Fair Value | 
322,500,000us-gaap_DebtInstrumentFairValue / us-gaap_DebtInstrumentAxis = mth_SeniorNotesDueTwoThousandTwentyMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember  | 
        
322,500,000us-gaap_DebtInstrumentFairValue / us-gaap_DebtInstrumentAxis = mth_SeniorNotesDueTwoThousandTwentyMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember  | 
      
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           7.00% senior notes due 2022 [Member] 
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| Debt Instrument [Line Items] | ||
| Aggregate Principal | 
300,000,000us-gaap_DebtInstrumentFaceAmount / us-gaap_DebtInstrumentAxis = mth_SeniorNotesDueTwoThousandTwentyTwoMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember  | 
        
300,000,000us-gaap_DebtInstrumentFaceAmount / us-gaap_DebtInstrumentAxis = mth_SeniorNotesDueTwoThousandTwentyTwoMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember  | 
      
| Fair value of fixed-rate debt | ||
| Estimated Fair Value | 
320,250,000us-gaap_DebtInstrumentFairValue / us-gaap_DebtInstrumentAxis = mth_SeniorNotesDueTwoThousandTwentyTwoMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember  | 
        
318,000,000us-gaap_DebtInstrumentFairValue / us-gaap_DebtInstrumentAxis = mth_SeniorNotesDueTwoThousandTwentyTwoMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember  | 
      
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           1.875% convertible senior notes due 2032 [Member] 
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| Debt Instrument [Line Items] | ||
| Aggregate Principal | 
126,500,000us-gaap_DebtInstrumentFaceAmount / us-gaap_DebtInstrumentAxis = mth_ConvertibleSeniorNotesDueTwoThousandThirtyTwoMemberMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember  | 
        
126,500,000us-gaap_DebtInstrumentFaceAmount / us-gaap_DebtInstrumentAxis = mth_ConvertibleSeniorNotesDueTwoThousandThirtyTwoMemberMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember  | 
      
| Fair value of fixed-rate debt | ||
| Estimated Fair Value | 
$ 134,564,000us-gaap_DebtInstrumentFairValue / us-gaap_DebtInstrumentAxis = mth_ConvertibleSeniorNotesDueTwoThousandThirtyTwoMemberMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember  | 
        
$ 124,444,000us-gaap_DebtInstrumentFairValue / us-gaap_DebtInstrumentAxis = mth_ConvertibleSeniorNotesDueTwoThousandThirtyTwoMemberMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember  | 
      
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- Definition 
          Face (par) amount of debt instrument at time of issuance. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Details 
          
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- Details 
          
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