v2.4.0.8

Organization, Description of Business And Basis Of Presentation Organization, Description of Business and Basis of Presentation (Narrative) (Details) | 3 Months Ended
--- | ---
Mar. 31, 2014
Organization and Description of Business [Line Items] |
Current Fiscal Year End Date | --12-31
Refined Products [Member] |
Organization and Description of Business [Line Items] |
Number of Pipeline Terminals | 54
Number of Independent Terminals | 27
Refined Products [Member] | Refined Products Transportation Services [Member] |
Organization and Description of Business [Line Items] |
Pipeline Length | 9,500
Refined Products [Member] | Ammonia Transportation Services [Member] |
Organization and Description of Business [Line Items] |
Pipeline Length | 1,100
Crude Oil Pipeline and Terminals [Member] |
Organization and Description of Business [Line Items] |
Pipeline Length | 1,100
Storage Capacity | 18,000,000
Leaseable Storage Capacity | 12,000,000
Marine Storage [Member] |
Organization and Description of Business [Line Items] |
Number of Independent Terminals | 5
Storage Capacity | 27,000,000

X
- Definition End date of current fiscal year in the format --MM-DD. + References No definition available. + Details
Name: | dei_CurrentFiscalYearEndDate
Namespace Prefix: | dei_
Data Type: | xbrli:gMonthDayItemType
Balance Type: | na
Period Type: | duration

X
- Definition Leasable Storage Capacity + References No definition available. + Details
Name: | mmp_LeaseableStorageCapacity
Namespace Prefix: | mmp_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of Independent Terminals + References No definition available. + Details
Name: | mmp_NumberofIndependentTerminals
Namespace Prefix: | mmp_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of PipelineTerminals + References No definition available. + Details
Name: | mmp_NumberOfPipelineTerminals
Namespace Prefix: | mmp_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | mmp_OrganizationAndDescriptionOfBusinessLineItems
Namespace Prefix: | mmp_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Pipeline, length + References No definition available. + Details
Name: | mmp_PipelineLength
Namespace Prefix: | mmp_
Data Type: | num:lengthItemType
Balance Type: | na
Period Type: | instant

X
- Definition Storage Capacity + References No definition available. + Details
Name: | mmp_StorageCapacity
Namespace Prefix: | mmp_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant