v3.8.0.1

Investments - Restricted Cash and Investments (Details) - USD ($) $ in Thousands | Sep. 30, 2017 | Dec. 31, 2016
--- | --- | ---
Restricted Cash and Investments Items [Line Items] |  |
Restricted cash | $ 131,598 | $ 103,788
Restricted investments | 4,729,224 | 4,295,008
Restricted cash and investments | 4,860,822 | 4,398,796
Amortized cost | 4,969,004 | 4,767,911
Third party agreements [Member] |  |
Restricted Cash and Investments Items [Line Items] |  |
Restricted cash | 80,999 | 56,891
Restricted investments | 1,354,548 | 1,299,569
Amortized cost | 1,337,185 | 1,307,926
Related party agreements [Member] |  |
Restricted Cash and Investments Items [Line Items] |  |
Restricted cash | 50,467 | 46,777
Restricted investments | 2,218,382 | 2,225,066
Amortized cost | 2,193,678 | 2,242,565
HTM related party agreements [Member] |  |
Restricted Cash and Investments Items [Line Items] |  |
Restricted investments | 1,152,106 | 766,135
Amortized cost | 1,118,368 | 752,212
US state regulatory authorities [Member] |  |
Restricted Cash and Investments Items [Line Items] |  |
Restricted cash | 132 | 120
Restricted investments | 4,188 | 4,238
Amortized cost | $ 4,071 | $ 4,059

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- Definition Investments, Original or Amortized Cost Basis + References No definition available. + Details
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Namespace Prefix: | mhld_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Restricted Cash and Investments [Line Items] + References No definition available. + Details
Name: | mhld_RestrictedCashAndInvestmentsLineItems
Namespace Prefix: | mhld_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. This element is for unclassified presentations; for classified presentations there is a separate and distinct element. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Cash and investments whose use in whole or in part is restricted for the long-term, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet. + References No definition available. + Details
Name: | us-gaap_RestrictedCashAndInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Investments which are not defined as or included in marketable (debt, equity, or other) securities whose use is restricted in whole or in part, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet. + References No definition available. + Details
Name: | us-gaap_RestrictedInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | mhld_RestrictedCashAndInvestmentsTypeAxis=mhld_RelatedPartyAgreementsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | mhld_RestrictedCashAndInvestmentsTypeAxis=mhld_UsStateRegulatoryAuthoritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |