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Major Lessees - Additional Information (Detail) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2015 USD ($)
Alpha Natural Resources |
Operating Leased Assets [Line Items] |
Non-recurring lease assignment fee | $ 6.0

X
- Definition Revenue From Lease Assignment Fees, Nonrecurring + References No definition available. + Details
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Namespace Prefix: | nrp_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_OperatingLeasedAssetsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_LeaseArrangementTypeAxis=nrp_AlphaNaturalResourcesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |