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Mineral Rights - Additional Information (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Extractive Industries [Abstract] |  |  |
Total depletion and amortization expense on mineral interests | $ 80.3 | $ 68.6 | $ 54.6

X
- Definition Depletion and amortization expense on coal and other mineral rights. + References No definition available. + Details
Name: | nrp_DepletionAndAmortizationExpenseOnCoalAndOtherMineralRights
Namespace Prefix: | nrp_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_ExtractiveIndustriesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration