Annual report pursuant to Section 13 and 15(d)

Loans Payable and Other Borrowings Details Textual (Details)

v2.4.1.9
Loans Payable and Other Borrowings Details Textual (Details) (USD $)
3 Months Ended 12 Months Ended
Dec. 31, 2014
Dec. 31, 2014
Dec. 31, 2013
Jul. 24, 2012
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum   0.00%us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMinimum    
Debt Instrument, Interest Rate, Effective Percentage Rate Range, Maximum   6.00%us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMaximum    
Debt Instrument, Maturity Date   Jun. 13, 2018    
Proceeds from Long-term Lines of Credit $ 110,000,000us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod      
Letters of Credit Outstanding, Amount 19,489,000us-gaap_LettersOfCreditOutstandingAmount 19,489,000us-gaap_LettersOfCreditOutstandingAmount 42,068,000us-gaap_LettersOfCreditOutstandingAmount  
Revolving Credit Facility [Member]        
Line of Credit Facility, Maximum Borrowing Capacity 400,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
400,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
  125,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
Minimum Tangible Net Worth 670,300,000mth_MinimumTangibleNetWorth
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
670,300,000mth_MinimumTangibleNetWorth
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
   
Leverage ratio 60.00%mth_LeverageRatio
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
60.00%mth_LeverageRatio
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
   
Interest Coverage Ratio 1.50mth_InterestCoverageRatio
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
1.50mth_InterestCoverageRatio
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
   
Long-term Line of Credit 0us-gaap_LineOfCredit
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
0us-gaap_LineOfCredit
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
0us-gaap_LineOfCredit
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
 
Line of Credit Facility, Remaining Borrowing Capacity 380,511,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
380,511,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
   
Letter of Credit [Member]        
Line of Credit Facility, Maximum Borrowing Capacity $ 200,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ us-gaap_ShortTermDebtTypeAxis
= us-gaap_LetterOfCreditMember
$ 200,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ us-gaap_ShortTermDebtTypeAxis
= us-gaap_LetterOfCreditMember