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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

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- 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