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Note 1 - Summary of Significant Accounting Policies - Estimated Useful Lives (Details) | 12 Months Ended
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Dec. 31, 2018
Tractor [Member] |
Property, Plant and Equipment, Useful Life | 5 years
Trailer [Member] |
Property, Plant and Equipment, Useful Life | 7 years
Service And Other Equipment [Member] | Minimum [Member] |
Property, Plant and Equipment, Useful Life | 3 years
Service And Other Equipment [Member] | Maximum [Member] |
Property, Plant and Equipment, Useful Life | 15 years
Building and Building Improvements [Member] | Minimum [Member] |
Property, Plant and Equipment, Useful Life | 20 years
Building and Building Improvements [Member] | Maximum [Member] |
Property, Plant and Equipment, Useful Life | 40 years

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- Definition Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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

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- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=mrtn_TrailerMember
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
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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
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |